var check = require('./util/check')
var extend = require('./util/extend')
var createEnvironment = require('./util/codegen')
var loop = require('./util/loop')
var isTypedArray = require('./util/is-typed-array')
var isNDArray = require('./util/is-ndarray')
var isArrayLike = require('./util/is-array-like')
var dynamic = require('./dynamic')

var primTypes = require('./constants/primitives.json')
var glTypes = require('./constants/dtypes.json')

// "cute" names for vector components
var CUTE_COMPONENTS = 'xyzw'.split('')

var GL_UNSIGNED_BYTE = 5121

var ATTRIB_STATE_POINTER = 1
var ATTRIB_STATE_CONSTANT = 2

var DYN_FUNC = 0
var DYN_PROP = 1
var DYN_CONTEXT = 2
var DYN_STATE = 3
var DYN_THUNK = 4
var DYN_CONSTANT = 5
var DYN_ARRAY = 6

var S_DITHER = 'dither'
var S_BLEND_ENABLE = 'blend.enable'
var S_BLEND_COLOR = 'blend.color'
var S_BLEND_EQUATION = 'blend.equation'
var S_BLEND_FUNC = 'blend.func'
var S_DEPTH_ENABLE = 'depth.enable'
var S_DEPTH_FUNC = 'depth.func'
var S_DEPTH_RANGE = 'depth.range'
var S_DEPTH_MASK = 'depth.mask'
var S_COLOR_MASK = 'colorMask'
var S_CULL_ENABLE = 'cull.enable'
var S_CULL_FACE = 'cull.face'
var S_FRONT_FACE = 'frontFace'
var S_LINE_WIDTH = 'lineWidth'
var S_POLYGON_OFFSET_ENABLE = 'polygonOffset.enable'
var S_POLYGON_OFFSET_OFFSET = 'polygonOffset.offset'
var S_SAMPLE_ALPHA = 'sample.alpha'
var S_SAMPLE_ENABLE = 'sample.enable'
var S_SAMPLE_COVERAGE = 'sample.coverage'
var S_STENCIL_ENABLE = 'stencil.enable'
var S_STENCIL_MASK = 'stencil.mask'
var S_STENCIL_FUNC = 'stencil.func'
var S_STENCIL_OPFRONT = 'stencil.opFront'
var S_STENCIL_OPBACK = 'stencil.opBack'
var S_SCISSOR_ENABLE = 'scissor.enable'
var S_SCISSOR_BOX = 'scissor.box'
var S_VIEWPORT = 'viewport'

var S_PROFILE = 'profile'

var S_FRAMEBUFFER = 'framebuffer'
var S_VERT = 'vert'
var S_FRAG = 'frag'
var S_ELEMENTS = 'elements'
var S_PRIMITIVE = 'primitive'
var S_COUNT = 'count'
var S_OFFSET = 'offset'
var S_INSTANCES = 'instances'
var S_VAO = 'vao'

var SUFFIX_WIDTH = 'Width'
var SUFFIX_HEIGHT = 'Height'

var S_FRAMEBUFFER_WIDTH = S_FRAMEBUFFER + SUFFIX_WIDTH
var S_FRAMEBUFFER_HEIGHT = S_FRAMEBUFFER + SUFFIX_HEIGHT
var S_VIEWPORT_WIDTH = S_VIEWPORT + SUFFIX_WIDTH
var S_VIEWPORT_HEIGHT = S_VIEWPORT + SUFFIX_HEIGHT
var S_DRAWINGBUFFER = 'drawingBuffer'
var S_DRAWINGBUFFER_WIDTH = S_DRAWINGBUFFER + SUFFIX_WIDTH
var S_DRAWINGBUFFER_HEIGHT = S_DRAWINGBUFFER + SUFFIX_HEIGHT

var NESTED_OPTIONS = [
  S_BLEND_FUNC,
  S_BLEND_EQUATION,
  S_STENCIL_FUNC,
  S_STENCIL_OPFRONT,
  S_STENCIL_OPBACK,
  S_SAMPLE_COVERAGE,
  S_VIEWPORT,
  S_SCISSOR_BOX,
  S_POLYGON_OFFSET_OFFSET
]

var GL_ARRAY_BUFFER = 34962
var GL_ELEMENT_ARRAY_BUFFER = 34963

var GL_FRAGMENT_SHADER = 35632
var GL_VERTEX_SHADER = 35633

var GL_TEXTURE_2D = 0x0DE1
var GL_TEXTURE_CUBE_MAP = 0x8513

var GL_CULL_FACE = 0x0B44
var GL_BLEND = 0x0BE2
var GL_DITHER = 0x0BD0
var GL_STENCIL_TEST = 0x0B90
var GL_DEPTH_TEST = 0x0B71
var GL_SCISSOR_TEST = 0x0C11
var GL_POLYGON_OFFSET_FILL = 0x8037
var GL_SAMPLE_ALPHA_TO_COVERAGE = 0x809E
var GL_SAMPLE_COVERAGE = 0x80A0

var GL_FLOAT = 5126
var GL_FLOAT_VEC2 = 35664
var GL_FLOAT_VEC3 = 35665
var GL_FLOAT_VEC4 = 35666
var GL_INT = 5124
var GL_INT_VEC2 = 35667
var GL_INT_VEC3 = 35668
var GL_INT_VEC4 = 35669
var GL_BOOL = 35670
var GL_BOOL_VEC2 = 35671
var GL_BOOL_VEC3 = 35672
var GL_BOOL_VEC4 = 35673
var GL_FLOAT_MAT2 = 35674
var GL_FLOAT_MAT3 = 35675
var GL_FLOAT_MAT4 = 35676
var GL_SAMPLER_2D = 35678
var GL_SAMPLER_CUBE = 35680

var GL_TRIANGLES = 4

var GL_FRONT = 1028
var GL_BACK = 1029
var GL_CW = 0x0900
var GL_CCW = 0x0901
var GL_MIN_EXT = 0x8007
var GL_MAX_EXT = 0x8008
var GL_ALWAYS = 519
var GL_KEEP = 7680
var GL_ZERO = 0
var GL_ONE = 1
var GL_FUNC_ADD = 0x8006
var GL_LESS = 513

var GL_FRAMEBUFFER = 0x8D40
var GL_COLOR_ATTACHMENT0 = 0x8CE0

var blendFuncs = {
  '0': 0,
  '1': 1,
  'zero': 0,
  'one': 1,
  'src color': 768,
  'one minus src color': 769,
  'src alpha': 770,
  'one minus src alpha': 771,
  'dst color': 774,
  'one minus dst color': 775,
  'dst alpha': 772,
  'one minus dst alpha': 773,
  'constant color': 32769,
  'one minus constant color': 32770,
  'constant alpha': 32771,
  'one minus constant alpha': 32772,
  'src alpha saturate': 776
}

// There are invalid values for srcRGB and dstRGB. See:
// https://www.khronos.org/registry/webgl/specs/1.0/#6.13
// https://github.com/KhronosGroup/WebGL/blob/0d3201f5f7ec3c0060bc1f04077461541f1987b9/conformance-suites/1.0.3/conformance/misc/webgl-specific.html#L56
var invalidBlendCombinations = [
  'constant color, constant alpha',
  'one minus constant color, constant alpha',
  'constant color, one minus constant alpha',
  'one minus constant color, one minus constant alpha',
  'constant alpha, constant color',
  'constant alpha, one minus constant color',
  'one minus constant alpha, constant color',
  'one minus constant alpha, one minus constant color'
]

var compareFuncs = {
  'never': 512,
  'less': 513,
  '<': 513,
  'equal': 514,
  '=': 514,
  '==': 514,
  '===': 514,
  'lequal': 515,
  '<=': 515,
  'greater': 516,
  '>': 516,
  'notequal': 517,
  '!=': 517,
  '!==': 517,
  'gequal': 518,
  '>=': 518,
  'always': 519
}

var stencilOps = {
  '0': 0,
  'zero': 0,
  'keep': 7680,
  'replace': 7681,
  'increment': 7682,
  'decrement': 7683,
  'increment wrap': 34055,
  'decrement wrap': 34056,
  'invert': 5386
}

var shaderType = {
  'frag': GL_FRAGMENT_SHADER,
  'vert': GL_VERTEX_SHADER
}

var orientationType = {
  'cw': GL_CW,
  'ccw': GL_CCW
}

function isBufferArgs (x) {
  return Array.isArray(x) ||
    isTypedArray(x) ||
    isNDArray(x)
}

// Make sure viewport is processed first
function sortState (state) {
  return state.sort(function (a, b) {
    if (a === S_VIEWPORT) {
      return -1
    } else if (b === S_VIEWPORT) {
      return 1
    }
    return (a < b) ? -1 : 1
  })
}

function Declaration (thisDep, contextDep, propDep, append) {
  this.thisDep = thisDep
  this.contextDep = contextDep
  this.propDep = propDep
  this.append = append
}

function isStatic (decl) {
  return decl && !(decl.thisDep || decl.contextDep || decl.propDep)
}

function createStaticDecl (append) {
  return new Declaration(false, false, false, append)
}

function createDynamicDecl (dyn, append) {
  var type = dyn.type
  if (type === DYN_FUNC) {
    var numArgs = dyn.data.length
    return new Declaration(
      true,
      numArgs >= 1,
      numArgs >= 2,
      append)
  } else if (type === DYN_THUNK) {
    var data = dyn.data
    return new Declaration(
      data.thisDep,
      data.contextDep,
      data.propDep,
      append)
  } else if (type === DYN_CONSTANT) {
    return new Declaration(
      false,
      false,
      false,
      append)
  } else if (type === DYN_ARRAY) {
    var thisDep = false
    var contextDep = false
    var propDep = false
    for (var i = 0; i < dyn.data.length; ++i) {
      var subDyn = dyn.data[i]
      if (subDyn.type === DYN_PROP) {
        propDep = true
      } else if (subDyn.type === DYN_CONTEXT) {
        contextDep = true
      } else if (subDyn.type === DYN_STATE) {
        thisDep = true
      } else if (subDyn.type === DYN_FUNC) {
        thisDep = true
        var subArgs = subDyn.data
        if (subArgs >= 1) {
          contextDep = true
        }
        if (subArgs >= 2) {
          propDep = true
        }
      } else if (subDyn.type === DYN_THUNK) {
        thisDep = thisDep || subDyn.data.thisDep
        contextDep = contextDep || subDyn.data.contextDep
        propDep = propDep || subDyn.data.propDep
      }
    }
    return new Declaration(
      thisDep,
      contextDep,
      propDep,
      append)
  } else {
    return new Declaration(
      type === DYN_STATE,
      type === DYN_CONTEXT,
      type === DYN_PROP,
      append)
  }
}

var SCOPE_DECL = new Declaration(false, false, false, function () {})

module.exports = function reglCore (
  gl,
  stringStore,
  extensions,
  limits,
  bufferState,
  elementState,
  textureState,
  framebufferState,
  uniformState,
  attributeState,
  shaderState,
  drawState,
  contextState,
  timer,
  config) {
  var AttributeRecord = attributeState.Record

  var blendEquations = {
    'add': 32774,
    'subtract': 32778,
    'reverse subtract': 32779
  }
  if (extensions.ext_blend_minmax) {
    blendEquations.min = GL_MIN_EXT
    blendEquations.max = GL_MAX_EXT
  }

  var extInstancing = extensions.angle_instanced_arrays
  var extDrawBuffers = extensions.webgl_draw_buffers
  var extVertexArrays = extensions.oes_vertex_array_object

  // ===================================================
  // ===================================================
  // WEBGL STATE
  // ===================================================
  // ===================================================
  var currentState = {
    dirty: true,
    profile: config.profile
  }
  var nextState = {}
  var GL_STATE_NAMES = []
  var GL_FLAGS = {}
  var GL_VARIABLES = {}

  function propName (name) {
    return name.replace('.', '_')
  }

  function stateFlag (sname, cap, init) {
    var name = propName(sname)
    GL_STATE_NAMES.push(sname)
    nextState[name] = currentState[name] = !!init
    GL_FLAGS[name] = cap
  }

  function stateVariable (sname, func, init) {
    var name = propName(sname)
    GL_STATE_NAMES.push(sname)
    if (Array.isArray(init)) {
      currentState[name] = init.slice()
      nextState[name] = init.slice()
    } else {
      currentState[name] = nextState[name] = init
    }
    GL_VARIABLES[name] = func
  }

  // Dithering
  stateFlag(S_DITHER, GL_DITHER)

  // Blending
  stateFlag(S_BLEND_ENABLE, GL_BLEND)
  stateVariable(S_BLEND_COLOR, 'blendColor', [0, 0, 0, 0])
  stateVariable(S_BLEND_EQUATION, 'blendEquationSeparate',
    [GL_FUNC_ADD, GL_FUNC_ADD])
  stateVariable(S_BLEND_FUNC, 'blendFuncSeparate',
    [GL_ONE, GL_ZERO, GL_ONE, GL_ZERO])

  // Depth
  stateFlag(S_DEPTH_ENABLE, GL_DEPTH_TEST, true)
  stateVariable(S_DEPTH_FUNC, 'depthFunc', GL_LESS)
  stateVariable(S_DEPTH_RANGE, 'depthRange', [0, 1])
  stateVariable(S_DEPTH_MASK, 'depthMask', true)

  // Color mask
  stateVariable(S_COLOR_MASK, S_COLOR_MASK, [true, true, true, true])

  // Face culling
  stateFlag(S_CULL_ENABLE, GL_CULL_FACE)
  stateVariable(S_CULL_FACE, 'cullFace', GL_BACK)

  // Front face orientation
  stateVariable(S_FRONT_FACE, S_FRONT_FACE, GL_CCW)

  // Line width
  stateVariable(S_LINE_WIDTH, S_LINE_WIDTH, 1)

  // Polygon offset
  stateFlag(S_POLYGON_OFFSET_ENABLE, GL_POLYGON_OFFSET_FILL)
  stateVariable(S_POLYGON_OFFSET_OFFSET, 'polygonOffset', [0, 0])

  // Sample coverage
  stateFlag(S_SAMPLE_ALPHA, GL_SAMPLE_ALPHA_TO_COVERAGE)
  stateFlag(S_SAMPLE_ENABLE, GL_SAMPLE_COVERAGE)
  stateVariable(S_SAMPLE_COVERAGE, 'sampleCoverage', [1, false])

  // Stencil
  stateFlag(S_STENCIL_ENABLE, GL_STENCIL_TEST)
  stateVariable(S_STENCIL_MASK, 'stencilMask', -1)
  stateVariable(S_STENCIL_FUNC, 'stencilFunc', [GL_ALWAYS, 0, -1])
  stateVariable(S_STENCIL_OPFRONT, 'stencilOpSeparate',
    [GL_FRONT, GL_KEEP, GL_KEEP, GL_KEEP])
  stateVariable(S_STENCIL_OPBACK, 'stencilOpSeparate',
    [GL_BACK, GL_KEEP, GL_KEEP, GL_KEEP])

  // Scissor
  stateFlag(S_SCISSOR_ENABLE, GL_SCISSOR_TEST)
  stateVariable(S_SCISSOR_BOX, 'scissor',
    [0, 0, gl.drawingBufferWidth, gl.drawingBufferHeight])

  // Viewport
  stateVariable(S_VIEWPORT, S_VIEWPORT,
    [0, 0, gl.drawingBufferWidth, gl.drawingBufferHeight])

  // ===================================================
  // ===================================================
  // ENVIRONMENT
  // ===================================================
  // ===================================================
  var sharedState = {
    gl: gl,
    context: contextState,
    strings: stringStore,
    next: nextState,
    current: currentState,
    draw: drawState,
    elements: elementState,
    buffer: bufferState,
    shader: shaderState,
    attributes: attributeState.state,
    vao: attributeState,
    uniforms: uniformState,
    framebuffer: framebufferState,
    extensions: extensions,

    timer: timer,
    isBufferArgs: isBufferArgs
  }

  var sharedConstants = {
    primTypes: primTypes,
    compareFuncs: compareFuncs,
    blendFuncs: blendFuncs,
    blendEquations: blendEquations,
    stencilOps: stencilOps,
    glTypes: glTypes,
    orientationType: orientationType
  }

  check.optional(function () {
    sharedState.isArrayLike = isArrayLike
  })

  if (extDrawBuffers) {
    sharedConstants.backBuffer = [GL_BACK]
    sharedConstants.drawBuffer = loop(limits.maxDrawbuffers, function (i) {
      if (i === 0) {
        return [0]
      }
      return loop(i, function (j) {
        return GL_COLOR_ATTACHMENT0 + j
      })
    })
  }

  var drawCallCounter = 0
  function createREGLEnvironment () {
    var env = createEnvironment()
    var link = env.link
    var global = env.global
    env.id = drawCallCounter++

    env.batchId = '0'

    // link shared state
    var SHARED = link(sharedState)
    var shared = env.shared = {
      props: 'a0'
    }
    Object.keys(sharedState).forEach(function (prop) {
      shared[prop] = global.def(SHARED, '.', prop)
    })

    // Inject runtime assertion stuff for debug builds
    check.optional(function () {
      env.CHECK = link(check)
      env.commandStr = check.guessCommand()
      env.command = link(env.commandStr)
      env.assert = function (block, pred, message) {
        block(
          'if(!(', pred, '))',
          this.CHECK, '.commandRaise(', link(message), ',', this.command, ');')
      }

      sharedConstants.invalidBlendCombinations = invalidBlendCombinations
    })

    // Copy GL state variables over
    var nextVars = env.next = {}
    var currentVars = env.current = {}
    Object.keys(GL_VARIABLES).forEach(function (variable) {
      if (Array.isArray(currentState[variable])) {
        nextVars[variable] = global.def(shared.next, '.', variable)
        currentVars[variable] = global.def(shared.current, '.', variable)
      }
    })

    // Initialize shared constants
    var constants = env.constants = {}
    Object.keys(sharedConstants).forEach(function (name) {
      constants[name] = global.def(JSON.stringify(sharedConstants[name]))
    })

    // Helper function for calling a block
    env.invoke = function (block, x) {
      switch (x.type) {
        case DYN_FUNC:
          var argList = [
            'this',
            shared.context,
            shared.props,
            env.batchId
          ]
          return block.def(
            link(x.data), '.call(',
            argList.slice(0, Math.max(x.data.length + 1, 4)),
            ')')
        case DYN_PROP:
          return block.def(shared.props, x.data)
        case DYN_CONTEXT:
          return block.def(shared.context, x.data)
        case DYN_STATE:
          return block.def('this', x.data)
        case DYN_THUNK:
          x.data.append(env, block)
          return x.data.ref
        case DYN_CONSTANT:
          return x.data.toString()
        case DYN_ARRAY:
          return x.data.map(function (y) {
            return env.invoke(block, y)
          })
      }
    }

    env.attribCache = {}

    var scopeAttribs = {}
    env.scopeAttrib = function (name) {
      var id = stringStore.id(name)
      if (id in scopeAttribs) {
        return scopeAttribs[id]
      }
      var binding = attributeState.scope[id]
      if (!binding) {
        binding = attributeState.scope[id] = new AttributeRecord()
      }
      var result = scopeAttribs[id] = link(binding)
      return result
    }

    return env
  }

  // ===================================================
  // ===================================================
  // PARSING
  // ===================================================
  // ===================================================
  function parseProfile (options) {
    var staticOptions = options.static
    var dynamicOptions = options.dynamic

    var profileEnable
    if (S_PROFILE in staticOptions) {
      var value = !!staticOptions[S_PROFILE]
      profileEnable = createStaticDecl(function (env, scope) {
        return value
      })
      profileEnable.enable = value
    } else if (S_PROFILE in dynamicOptions) {
      var dyn = dynamicOptions[S_PROFILE]
      profileEnable = createDynamicDecl(dyn, function (env, scope) {
        return env.invoke(scope, dyn)
      })
    }

    return profileEnable
  }

  function parseFramebuffer (options, env) {
    var staticOptions = options.static
    var dynamicOptions = options.dynamic

    if (S_FRAMEBUFFER in staticOptions) {
      var framebuffer = staticOptions[S_FRAMEBUFFER]
      if (framebuffer) {
        framebuffer = framebufferState.getFramebuffer(framebuffer)
        check.command(framebuffer, 'invalid framebuffer object')
        return createStaticDecl(function (env, block) {
          var FRAMEBUFFER = env.link(framebuffer)
          var shared = env.shared
          block.set(
            shared.framebuffer,
            '.next',
            FRAMEBUFFER)
          var CONTEXT = shared.context
          block.set(
            CONTEXT,
            '.' + S_FRAMEBUFFER_WIDTH,
            FRAMEBUFFER + '.width')
          block.set(
            CONTEXT,
            '.' + S_FRAMEBUFFER_HEIGHT,
            FRAMEBUFFER + '.height')
          return FRAMEBUFFER
        })
      } else {
        return createStaticDecl(function (env, scope) {
          var shared = env.shared
          scope.set(
            shared.framebuffer,
            '.next',
            'null')
          var CONTEXT = shared.context
          scope.set(
            CONTEXT,
            '.' + S_FRAMEBUFFER_WIDTH,
            CONTEXT + '.' + S_DRAWINGBUFFER_WIDTH)
          scope.set(
            CONTEXT,
            '.' + S_FRAMEBUFFER_HEIGHT,
            CONTEXT + '.' + S_DRAWINGBUFFER_HEIGHT)
          return 'null'
        })
      }
    } else if (S_FRAMEBUFFER in dynamicOptions) {
      var dyn = dynamicOptions[S_FRAMEBUFFER]
      return createDynamicDecl(dyn, function (env, scope) {
        var FRAMEBUFFER_FUNC = env.invoke(scope, dyn)
        var shared = env.shared
        var FRAMEBUFFER_STATE = shared.framebuffer
        var FRAMEBUFFER = scope.def(
          FRAMEBUFFER_STATE, '.getFramebuffer(', FRAMEBUFFER_FUNC, ')')

        check.optional(function () {
          env.assert(scope,
            '!' + FRAMEBUFFER_FUNC + '||' + FRAMEBUFFER,
            'invalid framebuffer object')
        })

        scope.set(
          FRAMEBUFFER_STATE,
          '.next',
          FRAMEBUFFER)
        var CONTEXT = shared.context
        scope.set(
          CONTEXT,
          '.' + S_FRAMEBUFFER_WIDTH,
          FRAMEBUFFER + '?' + FRAMEBUFFER + '.width:' +
          CONTEXT + '.' + S_DRAWINGBUFFER_WIDTH)
        scope.set(
          CONTEXT,
          '.' + S_FRAMEBUFFER_HEIGHT,
          FRAMEBUFFER +
          '?' + FRAMEBUFFER + '.height:' +
          CONTEXT + '.' + S_DRAWINGBUFFER_HEIGHT)
        return FRAMEBUFFER
      })
    } else {
      return null
    }
  }

  function parseViewportScissor (options, framebuffer, env) {
    var staticOptions = options.static
    var dynamicOptions = options.dynamic

    function parseBox (param) {
      if (param in staticOptions) {
        var box = staticOptions[param]
        check.commandType(box, 'object', 'invalid ' + param, env.commandStr)

        var isStatic = true
        var x = box.x | 0
        var y = box.y | 0
        var w, h
        if ('width' in box) {
          w = box.width | 0
          check.command(w >= 0, 'invalid ' + param, env.commandStr)
        } else {
          isStatic = false
        }
        if ('height' in box) {
          h = box.height | 0
          check.command(h >= 0, 'invalid ' + param, env.commandStr)
        } else {
          isStatic = false
        }

        return new Declaration(
          !isStatic && framebuffer && framebuffer.thisDep,
          !isStatic && framebuffer && framebuffer.contextDep,
          !isStatic && framebuffer && framebuffer.propDep,
          function (env, scope) {
            var CONTEXT = env.shared.context
            var BOX_W = w
            if (!('width' in box)) {
              BOX_W = scope.def(CONTEXT, '.', S_FRAMEBUFFER_WIDTH, '-', x)
            }
            var BOX_H = h
            if (!('height' in box)) {
              BOX_H = scope.def(CONTEXT, '.', S_FRAMEBUFFER_HEIGHT, '-', y)
            }
            return [x, y, BOX_W, BOX_H]
          })
      } else if (param in dynamicOptions) {
        var dynBox = dynamicOptions[param]
        var result = createDynamicDecl(dynBox, function (env, scope) {
          var BOX = env.invoke(scope, dynBox)

          check.optional(function () {
            env.assert(scope,
              BOX + '&&typeof ' + BOX + '==="object"',
              'invalid ' + param)
          })

          var CONTEXT = env.shared.context
          var BOX_X = scope.def(BOX, '.x|0')
          var BOX_Y = scope.def(BOX, '.y|0')
          var BOX_W = scope.def(
            '"width" in ', BOX, '?', BOX, '.width|0:',
            '(', CONTEXT, '.', S_FRAMEBUFFER_WIDTH, '-', BOX_X, ')')
          var BOX_H = scope.def(
            '"height" in ', BOX, '?', BOX, '.height|0:',
            '(', CONTEXT, '.', S_FRAMEBUFFER_HEIGHT, '-', BOX_Y, ')')

          check.optional(function () {
            env.assert(scope,
              BOX_W + '>=0&&' +
              BOX_H + '>=0',
              'invalid ' + param)
          })

          return [BOX_X, BOX_Y, BOX_W, BOX_H]
        })
        if (framebuffer) {
          result.thisDep = result.thisDep || framebuffer.thisDep
          result.contextDep = result.contextDep || framebuffer.contextDep
          result.propDep = result.propDep || framebuffer.propDep
        }
        return result
      } else if (framebuffer) {
        return new Declaration(
          framebuffer.thisDep,
          framebuffer.contextDep,
          framebuffer.propDep,
          function (env, scope) {
            var CONTEXT = env.shared.context
            return [
              0, 0,
              scope.def(CONTEXT, '.', S_FRAMEBUFFER_WIDTH),
              scope.def(CONTEXT, '.', S_FRAMEBUFFER_HEIGHT)]
          })
      } else {
        return null
      }
    }

    var viewport = parseBox(S_VIEWPORT)

    if (viewport) {
      var prevViewport = viewport
      viewport = new Declaration(
        viewport.thisDep,
        viewport.contextDep,
        viewport.propDep,
        function (env, scope) {
          var VIEWPORT = prevViewport.append(env, scope)
          var CONTEXT = env.shared.context
          scope.set(
            CONTEXT,
            '.' + S_VIEWPORT_WIDTH,
            VIEWPORT[2])
          scope.set(
            CONTEXT,
            '.' + S_VIEWPORT_HEIGHT,
            VIEWPORT[3])
          return VIEWPORT
        })
    }

    return {
      viewport: viewport,
      scissor_box: parseBox(S_SCISSOR_BOX)
    }
  }

  function parseAttribLocations (options, attributes) {
    var staticOptions = options.static
    var staticProgram =
      typeof staticOptions[S_FRAG] === 'string' &&
      typeof staticOptions[S_VERT] === 'string'
    if (staticProgram) {
      if (Object.keys(attributes.dynamic).length > 0) {
        return null
      }
      var staticAttributes = attributes.static
      var sAttributes = Object.keys(staticAttributes)
      if (sAttributes.length > 0 && typeof staticAttributes[sAttributes[0]] === 'number') {
        var bindings = []
        for (var i = 0; i < sAttributes.length; ++i) {
          check(typeof staticAttributes[sAttributes[i]] === 'number', 'must specify all vertex attribute locations when using vaos')
          bindings.push([staticAttributes[sAttributes[i]] | 0, sAttributes[i]])
        }
        return bindings
      }
    }
    return null
  }

  function parseProgram (options, env, attribLocations) {
    var staticOptions = options.static
    var dynamicOptions = options.dynamic

    function parseShader (name) {
      if (name in staticOptions) {
        var id = stringStore.id(staticOptions[name])
        check.optional(function () {
          shaderState.shader(shaderType[name], id, check.guessCommand())
        })
        var result = createStaticDecl(function () {
          return id
        })
        result.id = id
        return result
      } else if (name in dynamicOptions) {
        var dyn = dynamicOptions[name]
        return createDynamicDecl(dyn, function (env, scope) {
          var str = env.invoke(scope, dyn)
          var id = scope.def(env.shared.strings, '.id(', str, ')')
          check.optional(function () {
            scope(
              env.shared.shader, '.shader(',
              shaderType[name], ',',
              id, ',',
              env.command, ');')
          })
          return id
        })
      }
      return null
    }

    var frag = parseShader(S_FRAG)
    var vert = parseShader(S_VERT)

    var program = null
    var progVar
    if (isStatic(frag) && isStatic(vert)) {
      program = shaderState.program(vert.id, frag.id, null, attribLocations)
      progVar = createStaticDecl(function (env, scope) {
        return env.link(program)
      })
    } else {
      progVar = new Declaration(
        (frag && frag.thisDep) || (vert && vert.thisDep),
        (frag && frag.contextDep) || (vert && vert.contextDep),
        (frag && frag.propDep) || (vert && vert.propDep),
        function (env, scope) {
          var SHADER_STATE = env.shared.shader
          var fragId
          if (frag) {
            fragId = frag.append(env, scope)
          } else {
            fragId = scope.def(SHADER_STATE, '.', S_FRAG)
          }
          var vertId
          if (vert) {
            vertId = vert.append(env, scope)
          } else {
            vertId = scope.def(SHADER_STATE, '.', S_VERT)
          }
          var progDef = SHADER_STATE + '.program(' + vertId + ',' + fragId
          check.optional(function () {
            progDef += ',' + env.command
          })
          return scope.def(progDef + ')')
        })
    }

    return {
      frag: frag,
      vert: vert,
      progVar: progVar,
      program: program
    }
  }

  function parseDraw (options, env) {
    var staticOptions = options.static
    var dynamicOptions = options.dynamic

    // TODO: should use VAO to get default values for offset properties
    // should move vao parse into here and out of the old stuff

    var staticDraw = {}
    var vaoActive = false

    function parseVAO () {
      if (S_VAO in staticOptions) {
        var vao = staticOptions[S_VAO]
        if (vao !== null && attributeState.getVAO(vao) === null) {
          vao = attributeState.createVAO(vao)
        }

        vaoActive = true
        staticDraw.vao = vao

        return createStaticDecl(function (env) {
          var vaoRef = attributeState.getVAO(vao)
          if (vaoRef) {
            return env.link(vaoRef)
          } else {
            return 'null'
          }
        })
      } else if (S_VAO in dynamicOptions) {
        vaoActive = true
        var dyn = dynamicOptions[S_VAO]
        return createDynamicDecl(dyn, function (env, scope) {
          var vaoRef = env.invoke(scope, dyn)
          return scope.def(env.shared.vao + '.getVAO(' + vaoRef + ')')
        })
      }
      return null
    }

    var vao = parseVAO()

    var elementsActive = false

    function parseElements () {
      if (S_ELEMENTS in staticOptions) {
        var elements = staticOptions[S_ELEMENTS]
        staticDraw.elements = elements
        if (isBufferArgs(elements)) {
          var e = staticDraw.elements = elementState.create(elements, true)
          elements = elementState.getElements(e)
          elementsActive = true
        } else if (elements) {
          elements = elementState.getElements(elements)
          elementsActive = true
          check.command(elements, 'invalid elements', env.commandStr)
        }

        var result = createStaticDecl(function (env, scope) {
          if (elements) {
            var result = env.link(elements)
            env.ELEMENTS = result
            return result
          }
          env.ELEMENTS = null
          return null
        })
        result.value = elements
        return result
      } else if (S_ELEMENTS in dynamicOptions) {
        elementsActive = true

        var dyn = dynamicOptions[S_ELEMENTS]
        return createDynamicDecl(dyn, function (env, scope) {
          var shared = env.shared

          var IS_BUFFER_ARGS = shared.isBufferArgs
          var ELEMENT_STATE = shared.elements

          var elementDefn = env.invoke(scope, dyn)
          var elements = scope.def('null')
          var elementStream = scope.def(IS_BUFFER_ARGS, '(', elementDefn, ')')

          var ifte = env.cond(elementStream)
            .then(elements, '=', ELEMENT_STATE, '.createStream(', elementDefn, ');')
            .else(elements, '=', ELEMENT_STATE, '.getElements(', elementDefn, ');')

          check.optional(function () {
            env.assert(ifte.else,
              '!' + elementDefn + '||' + elements,
              'invalid elements')
          })

          scope.entry(ifte)
          scope.exit(
            env.cond(elementStream)
              .then(ELEMENT_STATE, '.destroyStream(', elements, ');'))

          env.ELEMENTS = elements

          return elements
        })
      } else if (vaoActive) {
        return new Declaration(
          vao.thisDep,
          vao.contextDep,
          vao.propDep,
          function (env, scope) {
            return scope.def(env.shared.vao + '.currentVAO?' + env.shared.elements + '.getElements(' + env.shared.vao + '.currentVAO.elements):null')
          })
      }
      return null
    }

    var elements = parseElements()

    function parsePrimitive () {
      if (S_PRIMITIVE in staticOptions) {
        var primitive = staticOptions[S_PRIMITIVE]
        staticDraw.primitive = primitive
        check.commandParameter(primitive, primTypes, 'invalid primitve', env.commandStr)
        return createStaticDecl(function (env, scope) {
          return primTypes[primitive]
        })
      } else if (S_PRIMITIVE in dynamicOptions) {
        var dynPrimitive = dynamicOptions[S_PRIMITIVE]
        return createDynamicDecl(dynPrimitive, function (env, scope) {
          var PRIM_TYPES = env.constants.primTypes
          var prim = env.invoke(scope, dynPrimitive)
          check.optional(function () {
            env.assert(scope,
              prim + ' in ' + PRIM_TYPES,
              'invalid primitive, must be one of ' + Object.keys(primTypes))
          })
          return scope.def(PRIM_TYPES, '[', prim, ']')
        })
      } else if (elementsActive) {
        if (isStatic(elements)) {
          if (elements.value) {
            return createStaticDecl(function (env, scope) {
              return scope.def(env.ELEMENTS, '.primType')
            })
          } else {
            return createStaticDecl(function () {
              return GL_TRIANGLES
            })
          }
        } else {
          return new Declaration(
            elements.thisDep,
            elements.contextDep,
            elements.propDep,
            function (env, scope) {
              var elements = env.ELEMENTS
              return scope.def(elements, '?', elements, '.primType:', GL_TRIANGLES)
            })
        }
      } else if (vaoActive) {
        return new Declaration(
          vao.thisDep,
          vao.contextDep,
          vao.propDep,
          function (env, scope) {
            return scope.def(env.shared.vao + '.currentVAO?' + env.shared.vao + '.currentVAO.primitive:' + GL_TRIANGLES)
          })
      }
      return null
    }

    function parseParam (param, isOffset) {
      if (param in staticOptions) {
        var value = staticOptions[param] | 0
        if (isOffset) {
          staticDraw.offset = value
        } else {
          staticDraw.instances = value
        }
        check.command(!isOffset || value >= 0, 'invalid ' + param, env.commandStr)
        return createStaticDecl(function (env, scope) {
          if (isOffset) {
            env.OFFSET = value
          }
          return value
        })
      } else if (param in dynamicOptions) {
        var dynValue = dynamicOptions[param]
        return createDynamicDecl(dynValue, function (env, scope) {
          var result = env.invoke(scope, dynValue)
          if (isOffset) {
            env.OFFSET = result
            check.optional(function () {
              env.assert(scope,
                result + '>=0',
                'invalid ' + param)
            })
          }
          return result
        })
      } else if (isOffset) {
        if (elementsActive) {
          return createStaticDecl(function (env, scope) {
            env.OFFSET = 0
            return 0
          })
        } else if (vaoActive) {
          return new Declaration(
            vao.thisDep,
            vao.contextDep,
            vao.propDep,
            function (env, scope) {
              return scope.def(env.shared.vao + '.currentVAO?' + env.shared.vao + '.currentVAO.offset:0')
            })
        }
      } else if (vaoActive) {
        return new Declaration(
          vao.thisDep,
          vao.contextDep,
          vao.propDep,
          function (env, scope) {
            return scope.def(env.shared.vao + '.currentVAO?' + env.shared.vao + '.currentVAO.instances:-1')
          })
      }
      return null
    }

    var OFFSET = parseParam(S_OFFSET, true)

    function parseVertCount () {
      if (S_COUNT in staticOptions) {
        var count = staticOptions[S_COUNT] | 0
        staticDraw.count = count
        check.command(
          typeof count === 'number' && count >= 0, 'invalid vertex count', env.commandStr)
        return createStaticDecl(function () {
          return count
        })
      } else if (S_COUNT in dynamicOptions) {
        var dynCount = dynamicOptions[S_COUNT]
        return createDynamicDecl(dynCount, function (env, scope) {
          var result = env.invoke(scope, dynCount)
          check.optional(function () {
            env.assert(scope,
              'typeof ' + result + '==="number"&&' +
              result + '>=0&&' +
              result + '===(' + result + '|0)',
              'invalid vertex count')
          })
          return result
        })
      } else if (elementsActive) {
        if (isStatic(elements)) {
          if (elements) {
            if (OFFSET) {
              return new Declaration(
                OFFSET.thisDep,
                OFFSET.contextDep,
                OFFSET.propDep,
                function (env, scope) {
                  var result = scope.def(
                    env.ELEMENTS, '.vertCount-', env.OFFSET)

                  check.optional(function () {
                    env.assert(scope,
                      result + '>=0',
                      'invalid vertex offset/element buffer too small')
                  })

                  return result
                })
            } else {
              return createStaticDecl(function (env, scope) {
                return scope.def(env.ELEMENTS, '.vertCount')
              })
            }
          } else {
            var result = createStaticDecl(function () {
              return -1
            })
            check.optional(function () {
              result.MISSING = true
            })
            return result
          }
        } else {
          var variable = new Declaration(
            elements.thisDep || OFFSET.thisDep,
            elements.contextDep || OFFSET.contextDep,
            elements.propDep || OFFSET.propDep,
            function (env, scope) {
              var elements = env.ELEMENTS
              if (env.OFFSET) {
                return scope.def(elements, '?', elements, '.vertCount-',
                  env.OFFSET, ':-1')
              }
              return scope.def(elements, '?', elements, '.vertCount:-1')
            })
          check.optional(function () {
            variable.DYNAMIC = true
          })
          return variable
        }
      } else if (vaoActive) {
        var countVariable = new Declaration(
          vao.thisDep,
          vao.contextDep,
          vao.propDep,
          function (env, scope) {
            return scope.def(env.shared.vao, '.currentVAO?', env.shared.vao, '.currentVAO.count:-1')
          })
        return countVariable
      }
      return null
    }

    var primitive = parsePrimitive()
    var count = parseVertCount()
    var instances = parseParam(S_INSTANCES, false)

    return {
      elements: elements,
      primitive: primitive,
      count: count,
      instances: instances,
      offset: OFFSET,
      vao: vao,

      vaoActive: vaoActive,
      elementsActive: elementsActive,

      // static draw props
      static: staticDraw
    }
  }

  function parseGLState (options, env) {
    var staticOptions = options.static
    var dynamicOptions = options.dynamic

    var STATE = {}

    GL_STATE_NAMES.forEach(function (prop) {
      var param = propName(prop)

      function parseParam (parseStatic, parseDynamic) {
        if (prop in staticOptions) {
          var value = parseStatic(staticOptions[prop])
          STATE[param] = createStaticDecl(function () {
            return value
          })
        } else if (prop in dynamicOptions) {
          var dyn = dynamicOptions[prop]
          STATE[param] = createDynamicDecl(dyn, function (env, scope) {
            return parseDynamic(env, scope, env.invoke(scope, dyn))
          })
        }
      }

      switch (prop) {
        case S_CULL_ENABLE:
        case S_BLEND_ENABLE:
        case S_DITHER:
        case S_STENCIL_ENABLE:
        case S_DEPTH_ENABLE:
        case S_SCISSOR_ENABLE:
        case S_POLYGON_OFFSET_ENABLE:
        case S_SAMPLE_ALPHA:
        case S_SAMPLE_ENABLE:
        case S_DEPTH_MASK:
          return parseParam(
            function (value) {
              check.commandType(value, 'boolean', prop, env.commandStr)
              return value
            },
            function (env, scope, value) {
              check.optional(function () {
                env.assert(scope,
                  'typeof ' + value + '==="boolean"',
                  'invalid flag ' + prop, env.commandStr)
              })
              return value
            })

        case S_DEPTH_FUNC:
          return parseParam(
            function (value) {
              check.commandParameter(value, compareFuncs, 'invalid ' + prop, env.commandStr)
              return compareFuncs[value]
            },
            function (env, scope, value) {
              var COMPARE_FUNCS = env.constants.compareFuncs
              check.optional(function () {
                env.assert(scope,
                  value + ' in ' + COMPARE_FUNCS,
                  'invalid ' + prop + ', must be one of ' + Object.keys(compareFuncs))
              })
              return scope.def(COMPARE_FUNCS, '[', value, ']')
            })

        case S_DEPTH_RANGE:
          return parseParam(
            function (value) {
              check.command(
                isArrayLike(value) &&
                value.length === 2 &&
                typeof value[0] === 'number' &&
                typeof value[1] === 'number' &&
                value[0] <= value[1],
                'depth range is 2d array',
                env.commandStr)
              return value
            },
            function (env, scope, value) {
              check.optional(function () {
                env.assert(scope,
                  env.shared.isArrayLike + '(' + value + ')&&' +
                  value + '.length===2&&' +
                  'typeof ' + value + '[0]==="number"&&' +
                  'typeof ' + value + '[1]==="number"&&' +
                  value + '[0]<=' + value + '[1]',
                  'depth range must be a 2d array')
              })

              var Z_NEAR = scope.def('+', value, '[0]')
              var Z_FAR = scope.def('+', value, '[1]')
              return [Z_NEAR, Z_FAR]
            })

        case S_BLEND_FUNC:
          return parseParam(
            function (value) {
              check.commandType(value, 'object', 'blend.func', env.commandStr)
              var srcRGB = ('srcRGB' in value ? value.srcRGB : value.src)
              var srcAlpha = ('srcAlpha' in value ? value.srcAlpha : value.src)
              var dstRGB = ('dstRGB' in value ? value.dstRGB : value.dst)
              var dstAlpha = ('dstAlpha' in value ? value.dstAlpha : value.dst)
              check.commandParameter(srcRGB, blendFuncs, param + '.srcRGB', env.commandStr)
              check.commandParameter(srcAlpha, blendFuncs, param + '.srcAlpha', env.commandStr)
              check.commandParameter(dstRGB, blendFuncs, param + '.dstRGB', env.commandStr)
              check.commandParameter(dstAlpha, blendFuncs, param + '.dstAlpha', env.commandStr)

              check.command(
                (invalidBlendCombinations.indexOf(srcRGB + ', ' + dstRGB) === -1),
                'unallowed blending combination (srcRGB, dstRGB) = (' + srcRGB + ', ' + dstRGB + ')', env.commandStr)

              return [
                blendFuncs[srcRGB],
                blendFuncs[dstRGB],
                blendFuncs[srcAlpha],
                blendFuncs[dstAlpha]
              ]
            },
            function (env, scope, value) {
              var BLEND_FUNCS = env.constants.blendFuncs

              check.optional(function () {
                env.assert(scope,
                  value + '&&typeof ' + value + '==="object"',
                  'invalid blend func, must be an object')
              })

              function read (prefix, suffix) {
                var func = scope.def(
                  '"', prefix, suffix, '" in ', value,
                  '?', value, '.', prefix, suffix,
                  ':', value, '.', prefix)

                check.optional(function () {
                  env.assert(scope,
                    func + ' in ' + BLEND_FUNCS,
                    'invalid ' + prop + '.' + prefix + suffix + ', must be one of ' + Object.keys(blendFuncs))
                })

                return func
              }

              var srcRGB = read('src', 'RGB')
              var dstRGB = read('dst', 'RGB')

              check.optional(function () {
                var INVALID_BLEND_COMBINATIONS = env.constants.invalidBlendCombinations

                env.assert(scope,
                  INVALID_BLEND_COMBINATIONS +
                           '.indexOf(' + srcRGB + '+", "+' + dstRGB + ') === -1 ',
                  'unallowed blending combination for (srcRGB, dstRGB)'
                )
              })

              var SRC_RGB = scope.def(BLEND_FUNCS, '[', srcRGB, ']')
              var SRC_ALPHA = scope.def(BLEND_FUNCS, '[', read('src', 'Alpha'), ']')
              var DST_RGB = scope.def(BLEND_FUNCS, '[', dstRGB, ']')
              var DST_ALPHA = scope.def(BLEND_FUNCS, '[', read('dst', 'Alpha'), ']')

              return [SRC_RGB, DST_RGB, SRC_ALPHA, DST_ALPHA]
            })

        case S_BLEND_EQUATION:
          return parseParam(
            function (value) {
              if (typeof value === 'string') {
                check.commandParameter(value, blendEquations, 'invalid ' + prop, env.commandStr)
                return [
                  blendEquations[value],
                  blendEquations[value]
                ]
              } else if (typeof value === 'object') {
                check.commandParameter(
                  value.rgb, blendEquations, prop + '.rgb', env.commandStr)
                check.commandParameter(
                  value.alpha, blendEquations, prop + '.alpha', env.commandStr)
                return [
                  blendEquations[value.rgb],
                  blendEquations[value.alpha]
                ]
              } else {
                check.commandRaise('invalid blend.equation', env.commandStr)
              }
            },
            function (env, scope, value) {
              var BLEND_EQUATIONS = env.constants.blendEquations

              var RGB = scope.def()
              var ALPHA = scope.def()

              var ifte = env.cond('typeof ', value, '==="string"')

              check.optional(function () {
                function checkProp (block, name, value) {
                  env.assert(block,
                    value + ' in ' + BLEND_EQUATIONS,
                    'invalid ' + name + ', must be one of ' + Object.keys(blendEquations))
                }
                checkProp(ifte.then, prop, value)

                env.assert(ifte.else,
                  value + '&&typeof ' + value + '==="object"',
                  'invalid ' + prop)
                checkProp(ifte.else, prop + '.rgb', value + '.rgb')
                checkProp(ifte.else, prop + '.alpha', value + '.alpha')
              })

              ifte.then(
                RGB, '=', ALPHA, '=', BLEND_EQUATIONS, '[', value, '];')
              ifte.else(
                RGB, '=', BLEND_EQUATIONS, '[', value, '.rgb];',
                ALPHA, '=', BLEND_EQUATIONS, '[', value, '.alpha];')

              scope(ifte)

              return [RGB, ALPHA]
            })

        case S_BLEND_COLOR:
          return parseParam(
            function (value) {
              check.command(
                isArrayLike(value) &&
                value.length === 4,
                'blend.color must be a 4d array', env.commandStr)
              return loop(4, function (i) {
                return +value[i]
              })
            },
            function (env, scope, value) {
              check.optional(function () {
                env.assert(scope,
                  env.shared.isArrayLike + '(' + value + ')&&' +
                  value + '.length===4',
                  'blend.color must be a 4d array')
              })
              return loop(4, function (i) {
                return scope.def('+', value, '[', i, ']')
              })
            })

        case S_STENCIL_MASK:
          return parseParam(
            function (value) {
              check.commandType(value, 'number', param, env.commandStr)
              return value | 0
            },
            function (env, scope, value) {
              check.optional(function () {
                env.assert(scope,
                  'typeof ' + value + '==="number"',
                  'invalid stencil.mask')
              })
              return scope.def(value, '|0')
            })

        case S_STENCIL_FUNC:
          return parseParam(
            function (value) {
              check.commandType(value, 'object', param, env.commandStr)
              var cmp = value.cmp || 'keep'
              var ref = value.ref || 0
              var mask = 'mask' in value ? value.mask : -1
              check.commandParameter(cmp, compareFuncs, prop + '.cmp', env.commandStr)
              check.commandType(ref, 'number', prop + '.ref', env.commandStr)
              check.commandType(mask, 'number', prop + '.mask', env.commandStr)
              return [
                compareFuncs[cmp],
                ref,
                mask
              ]
            },
            function (env, scope, value) {
              var COMPARE_FUNCS = env.constants.compareFuncs
              check.optional(function () {
                function assert () {
                  env.assert(scope,
                    Array.prototype.join.call(arguments, ''),
                    'invalid stencil.func')
                }
                assert(value + '&&typeof ', value, '==="object"')
                assert('!("cmp" in ', value, ')||(',
                  value, '.cmp in ', COMPARE_FUNCS, ')')
              })
              var cmp = scope.def(
                '"cmp" in ', value,
                '?', COMPARE_FUNCS, '[', value, '.cmp]',
                ':', GL_KEEP)
              var ref = scope.def(value, '.ref|0')
              var mask = scope.def(
                '"mask" in ', value,
                '?', value, '.mask|0:-1')
              return [cmp, ref, mask]
            })

        case S_STENCIL_OPFRONT:
        case S_STENCIL_OPBACK:
          return parseParam(
            function (value) {
              check.commandType(value, 'object', param, env.commandStr)
              var fail = value.fail || 'keep'
              var zfail = value.zfail || 'keep'
              var zpass = value.zpass || 'keep'
              check.commandParameter(fail, stencilOps, prop + '.fail', env.commandStr)
              check.commandParameter(zfail, stencilOps, prop + '.zfail', env.commandStr)
              check.commandParameter(zpass, stencilOps, prop + '.zpass', env.commandStr)
              return [
                prop === S_STENCIL_OPBACK ? GL_BACK : GL_FRONT,
                stencilOps[fail],
                stencilOps[zfail],
                stencilOps[zpass]
              ]
            },
            function (env, scope, value) {
              var STENCIL_OPS = env.constants.stencilOps

              check.optional(function () {
                env.assert(scope,
                  value + '&&typeof ' + value + '==="object"',
                  'invalid ' + prop)
              })

              function read (name) {
                check.optional(function () {
                  env.assert(scope,
                    '!("' + name + '" in ' + value + ')||' +
                    '(' + value + '.' + name + ' in ' + STENCIL_OPS + ')',
                    'invalid ' + prop + '.' + name + ', must be one of ' + Object.keys(stencilOps))
                })

                return scope.def(
                  '"', name, '" in ', value,
                  '?', STENCIL_OPS, '[', value, '.', name, ']:',
                  GL_KEEP)
              }

              return [
                prop === S_STENCIL_OPBACK ? GL_BACK : GL_FRONT,
                read('fail'),
                read('zfail'),
                read('zpass')
              ]
            })

        case S_POLYGON_OFFSET_OFFSET:
          return parseParam(
            function (value) {
              check.commandType(value, 'object', param, env.commandStr)
              var factor = value.factor | 0
              var units = value.units | 0
              check.commandType(factor, 'number', param + '.factor', env.commandStr)
              check.commandType(units, 'number', param + '.units', env.commandStr)
              return [factor, units]
            },
            function (env, scope, value) {
              check.optional(function () {
                env.assert(scope,
                  value + '&&typeof ' + value + '==="object"',
                  'invalid ' + prop)
              })

              var FACTOR = scope.def(value, '.factor|0')
              var UNITS = scope.def(value, '.units|0')

              return [FACTOR, UNITS]
            })

        case S_CULL_FACE:
          return parseParam(
            function (value) {
              var face = 0
              if (value === 'front') {
                face = GL_FRONT
              } else if (value === 'back') {
                face = GL_BACK
              }
              check.command(!!face, param, env.commandStr)
              return face
            },
            function (env, scope, value) {
              check.optional(function () {
                env.assert(scope,
                  value + '==="front"||' +
                  value + '==="back"',
                  'invalid cull.face')
              })
              return scope.def(value, '==="front"?', GL_FRONT, ':', GL_BACK)
            })

        case S_LINE_WIDTH:
          return parseParam(
            function (value) {
              check.command(
                typeof value === 'number' &&
                value >= limits.lineWidthDims[0] &&
                value <= limits.lineWidthDims[1],
                'invalid line width, must be a positive number between ' +
                limits.lineWidthDims[0] + ' and ' + limits.lineWidthDims[1], env.commandStr)
              return value
            },
            function (env, scope, value) {
              check.optional(function () {
                env.assert(scope,
                  'typeof ' + value + '==="number"&&' +
                  value + '>=' + limits.lineWidthDims[0] + '&&' +
                  value + '<=' + limits.lineWidthDims[1],
                  'invalid line width')
              })

              return value
            })

        case S_FRONT_FACE:
          return parseParam(
            function (value) {
              check.commandParameter(value, orientationType, param, env.commandStr)
              return orientationType[value]
            },
            function (env, scope, value) {
              check.optional(function () {
                env.assert(scope,
                  value + '==="cw"||' +
                  value + '==="ccw"',
                  'invalid frontFace, must be one of cw,ccw')
              })
              return scope.def(value + '==="cw"?' + GL_CW + ':' + GL_CCW)
            })

        case S_COLOR_MASK:
          return parseParam(
            function (value) {
              check.command(
                isArrayLike(value) && value.length === 4,
                'color.mask must be length 4 array', env.commandStr)
              return value.map(function (v) { return !!v })
            },
            function (env, scope, value) {
              check.optional(function () {
                env.assert(scope,
                  env.shared.isArrayLike + '(' + value + ')&&' +
                  value + '.length===4',
                  'invalid color.mask')
              })
              return loop(4, function (i) {
                return '!!' + value + '[' + i + ']'
              })
            })

        case S_SAMPLE_COVERAGE:
          return parseParam(
            function (value) {
              check.command(typeof value === 'object' && value, param, env.commandStr)
              var sampleValue = 'value' in value ? value.value : 1
              var sampleInvert = !!value.invert
              check.command(
                typeof sampleValue === 'number' &&
                sampleValue >= 0 && sampleValue <= 1,
                'sample.coverage.value must be a number between 0 and 1', env.commandStr)
              return [sampleValue, sampleInvert]
            },
            function (env, scope, value) {
              check.optional(function () {
                env.assert(scope,
                  value + '&&typeof ' + value + '==="object"',
                  'invalid sample.coverage')
              })
              var VALUE = scope.def(
                '"value" in ', value, '?+', value, '.value:1')
              var INVERT = scope.def('!!', value, '.invert')
              return [VALUE, INVERT]
            })
      }
    })

    return STATE
  }

  function parseUniforms (uniforms, env) {
    var staticUniforms = uniforms.static
    var dynamicUniforms = uniforms.dynamic

    var UNIFORMS = {}

    Object.keys(staticUniforms).forEach(function (name) {
      var value = staticUniforms[name]
      var result
      if (typeof value === 'number' ||
          typeof value === 'boolean') {
        result = createStaticDecl(function () {
          return value
        })
      } else if (typeof value === 'function') {
        var reglType = value._reglType
        if (reglType === 'texture2d' ||
            reglType === 'textureCube') {
          result = createStaticDecl(function (env) {
            return env.link(value)
          })
        } else if (reglType === 'framebuffer' ||
                   reglType === 'framebufferCube') {
          check.command(value.color.length > 0,
            'missing color attachment for framebuffer sent to uniform "' + name + '"', env.commandStr)
          result = createStaticDecl(function (env) {
            return env.link(value.color[0])
          })
        } else {
          check.commandRaise('invalid data for uniform "' + name + '"', env.commandStr)
        }
      } else if (isArrayLike(value)) {
        result = createStaticDecl(function (env) {
          var ITEM = env.global.def('[',
            loop(value.length, function (i) {
              check.command(
                typeof value[i] === 'number' ||
                typeof value[i] === 'boolean',
                'invalid uniform ' + name, env.commandStr)
              return value[i]
            }), ']')
          return ITEM
        })
      } else {
        check.commandRaise('invalid or missing data for uniform "' + name + '"', env.commandStr)
      }
      result.value = value
      UNIFORMS[name] = result
    })

    Object.keys(dynamicUniforms).forEach(function (key) {
      var dyn = dynamicUniforms[key]
      UNIFORMS[key] = createDynamicDecl(dyn, function (env, scope) {
        return env.invoke(scope, dyn)
      })
    })

    return UNIFORMS
  }

  function parseAttributes (attributes, env) {
    var staticAttributes = attributes.static
    var dynamicAttributes = attributes.dynamic

    var attributeDefs = {}

    Object.keys(staticAttributes).forEach(function (attribute) {
      var value = staticAttributes[attribute]
      var id = stringStore.id(attribute)

      var record = new AttributeRecord()
      if (isBufferArgs(value)) {
        record.state = ATTRIB_STATE_POINTER
        record.buffer = bufferState.getBuffer(
          bufferState.create(value, GL_ARRAY_BUFFER, false, true))
        record.type = 0
      } else {
        var buffer = bufferState.getBuffer(value)
        if (buffer) {
          record.state = ATTRIB_STATE_POINTER
          record.buffer = buffer
          record.type = 0
        } else {
          check.command(typeof value === 'object' && value,
            'invalid data for attribute ' + attribute, env.commandStr)
          if ('constant' in value) {
            var constant = value.constant
            record.buffer = 'null'
            record.state = ATTRIB_STATE_CONSTANT
            if (typeof constant === 'number') {
              record.x = constant
            } else {
              check.command(
                isArrayLike(constant) &&
                constant.length > 0 &&
                constant.length <= 4,
                'invalid constant for attribute ' + attribute, env.commandStr)
              CUTE_COMPONENTS.forEach(function (c, i) {
                if (i < constant.length) {
                  record[c] = constant[i]
                }
              })
            }
          } else {
            if (isBufferArgs(value.buffer)) {
              buffer = bufferState.getBuffer(
                bufferState.create(value.buffer, GL_ARRAY_BUFFER, false, true))
            } else {
              buffer = bufferState.getBuffer(value.buffer)
            }
            check.command(!!buffer, 'missing buffer for attribute "' + attribute + '"', env.commandStr)

            var offset = value.offset | 0
            check.command(offset >= 0,
              'invalid offset for attribute "' + attribute + '"', env.commandStr)

            var stride = value.stride | 0
            check.command(stride >= 0 && stride < 256,
              'invalid stride for attribute "' + attribute + '", must be integer betweeen [0, 255]', env.commandStr)

            var size = value.size | 0
            check.command(!('size' in value) || (size > 0 && size <= 4),
              'invalid size for attribute "' + attribute + '", must be 1,2,3,4', env.commandStr)

            var normalized = !!value.normalized

            var type = 0
            if ('type' in value) {
              check.commandParameter(
                value.type, glTypes,
                'invalid type for attribute ' + attribute, env.commandStr)
              type = glTypes[value.type]
            }

            var divisor = value.divisor | 0
            check.optional(function () {
              if ('divisor' in value) {
                check.command(divisor === 0 || extInstancing,
                  'cannot specify divisor for attribute "' + attribute + '", instancing not supported', env.commandStr)
                check.command(divisor >= 0,
                  'invalid divisor for attribute "' + attribute + '"', env.commandStr)
              }

              var command = env.commandStr

              var VALID_KEYS = [
                'buffer',
                'offset',
                'divisor',
                'normalized',
                'type',
                'size',
                'stride'
              ]

              Object.keys(value).forEach(function (prop) {
                check.command(
                  VALID_KEYS.indexOf(prop) >= 0,
                  'unknown parameter "' + prop + '" for attribute pointer "' + attribute + '" (valid parameters are ' + VALID_KEYS + ')',
                  command)
              })
            })

            record.buffer = buffer
            record.state = ATTRIB_STATE_POINTER
            record.size = size
            record.normalized = normalized
            record.type = type || buffer.dtype
            record.offset = offset
            record.stride = stride
            record.divisor = divisor
          }
        }
      }

      attributeDefs[attribute] = createStaticDecl(function (env, scope) {
        var cache = env.attribCache
        if (id in cache) {
          return cache[id]
        }
        var result = {
          isStream: false
        }
        Object.keys(record).forEach(function (key) {
          result[key] = record[key]
        })
        if (record.buffer) {
          result.buffer = env.link(record.buffer)
          result.type = result.type || (result.buffer + '.dtype')
        }
        cache[id] = result
        return result
      })
    })

    Object.keys(dynamicAttributes).forEach(function (attribute) {
      var dyn = dynamicAttributes[attribute]

      function appendAttributeCode (env, block) {
        var VALUE = env.invoke(block, dyn)

        var shared = env.shared
        var constants = env.constants

        var IS_BUFFER_ARGS = shared.isBufferArgs
        var BUFFER_STATE = shared.buffer

        // Perform validation on attribute
        check.optional(function () {
          env.assert(block,
            VALUE + '&&(typeof ' + VALUE + '==="object"||typeof ' +
            VALUE + '==="function")&&(' +
            IS_BUFFER_ARGS + '(' + VALUE + ')||' +
            BUFFER_STATE + '.getBuffer(' + VALUE + ')||' +
            BUFFER_STATE + '.getBuffer(' + VALUE + '.buffer)||' +
            IS_BUFFER_ARGS + '(' + VALUE + '.buffer)||' +
            '("constant" in ' + VALUE +
            '&&(typeof ' + VALUE + '.constant==="number"||' +
            shared.isArrayLike + '(' + VALUE + '.constant))))',
            'invalid dynamic attribute "' + attribute + '"')
        })

        // allocate names for result
        var result = {
          isStream: block.def(false)
        }
        var defaultRecord = new AttributeRecord()
        defaultRecord.state = ATTRIB_STATE_POINTER
        Object.keys(defaultRecord).forEach(function (key) {
          result[key] = block.def('' + defaultRecord[key])
        })

        var BUFFER = result.buffer
        var TYPE = result.type
        block(
          'if(', IS_BUFFER_ARGS, '(', VALUE, ')){',
          result.isStream, '=true;',
          BUFFER, '=', BUFFER_STATE, '.createStream(', GL_ARRAY_BUFFER, ',', VALUE, ');',
          TYPE, '=', BUFFER, '.dtype;',
          '}else{',
          BUFFER, '=', BUFFER_STATE, '.getBuffer(', VALUE, ');',
          'if(', BUFFER, '){',
          TYPE, '=', BUFFER, '.dtype;',
          '}else if("constant" in ', VALUE, '){',
          result.state, '=', ATTRIB_STATE_CONSTANT, ';',
          'if(typeof ' + VALUE + '.constant === "number"){',
          result[CUTE_COMPONENTS[0]], '=', VALUE, '.constant;',
          CUTE_COMPONENTS.slice(1).map(function (n) {
            return result[n]
          }).join('='), '=0;',
          '}else{',
          CUTE_COMPONENTS.map(function (name, i) {
            return (
              result[name] + '=' + VALUE + '.constant.length>' + i +
              '?' + VALUE + '.constant[' + i + ']:0;'
            )
          }).join(''),
          '}}else{',
          'if(', IS_BUFFER_ARGS, '(', VALUE, '.buffer)){',
          BUFFER, '=', BUFFER_STATE, '.createStream(', GL_ARRAY_BUFFER, ',', VALUE, '.buffer);',
          '}else{',
          BUFFER, '=', BUFFER_STATE, '.getBuffer(', VALUE, '.buffer);',
          '}',
          TYPE, '="type" in ', VALUE, '?',
          constants.glTypes, '[', VALUE, '.type]:', BUFFER, '.dtype;',
          result.normalized, '=!!', VALUE, '.normalized;')
        function emitReadRecord (name) {
          block(result[name], '=', VALUE, '.', name, '|0;')
        }
        emitReadRecord('size')
        emitReadRecord('offset')
        emitReadRecord('stride')
        emitReadRecord('divisor')

        block('}}')

        block.exit(
          'if(', result.isStream, '){',
          BUFFER_STATE, '.destroyStream(', BUFFER, ');',
          '}')

        return result
      }

      attributeDefs[attribute] = createDynamicDecl(dyn, appendAttributeCode)
    })

    return attributeDefs
  }

  function parseContext (context) {
    var staticContext = context.static
    var dynamicContext = context.dynamic
    var result = {}

    Object.keys(staticContext).forEach(function (name) {
      var value = staticContext[name]
      result[name] = createStaticDecl(function (env, scope) {
        if (typeof value === 'number' || typeof value === 'boolean') {
          return '' + value
        } else {
          return env.link(value)
        }
      })
    })

    Object.keys(dynamicContext).forEach(function (name) {
      var dyn = dynamicContext[name]
      result[name] = createDynamicDecl(dyn, function (env, scope) {
        return env.invoke(scope, dyn)
      })
    })

    return result
  }

  function parseArguments (options, attributes, uniforms, context, env) {
    var staticOptions = options.static
    var dynamicOptions = options.dynamic

    check.optional(function () {
      var KEY_NAMES = [
        S_FRAMEBUFFER,
        S_VERT,
        S_FRAG,
        S_ELEMENTS,
        S_PRIMITIVE,
        S_OFFSET,
        S_COUNT,
        S_INSTANCES,
        S_PROFILE,
        S_VAO
      ].concat(GL_STATE_NAMES)

      function checkKeys (dict) {
        Object.keys(dict).forEach(function (key) {
          check.command(
            KEY_NAMES.indexOf(key) >= 0,
            'unknown parameter "' + key + '"',
            env.commandStr)
        })
      }

      checkKeys(staticOptions)
      checkKeys(dynamicOptions)
    })

    var attribLocations = parseAttribLocations(options, attributes)

    var framebuffer = parseFramebuffer(options, env)
    var viewportAndScissor = parseViewportScissor(options, framebuffer, env)
    var draw = parseDraw(options, env)
    var state = parseGLState(options, env)
    var shader = parseProgram(options, env, attribLocations)

    function copyBox (name) {
      var defn = viewportAndScissor[name]
      if (defn) {
        state[name] = defn
      }
    }
    copyBox(S_VIEWPORT)
    copyBox(propName(S_SCISSOR_BOX))

    var dirty = Object.keys(state).length > 0

    var result = {
      framebuffer: framebuffer,
      draw: draw,
      shader: shader,
      state: state,
      dirty: dirty,
      scopeVAO: null,
      drawVAO: null,
      useVAO: false,
      attributes: {}
    }

    result.profile = parseProfile(options, env)
    result.uniforms = parseUniforms(uniforms, env)
    result.drawVAO = result.scopeVAO = draw.vao
    // special case: check if we can statically allocate a vertex array object for this program
    if (!result.drawVAO &&
      shader.program &&
      !attribLocations &&
      extensions.angle_instanced_arrays &&
      draw.static.elements) {
      var useVAO = true
      var staticBindings = shader.program.attributes.map(function (attr) {
        var binding = attributes.static[attr]
        useVAO = useVAO && !!binding
        return binding
      })
      if (useVAO && staticBindings.length > 0) {
        var vao = attributeState.getVAO(attributeState.createVAO({
          attributes: staticBindings,
          elements: draw.static.elements
        }))
        result.drawVAO = new Declaration(null, null, null, function (env, scope) {
          return env.link(vao)
        })
        result.useVAO = true
      }
    }
    if (attribLocations) {
      result.useVAO = true
    } else {
      result.attributes = parseAttributes(attributes, env)
    }
    result.context = parseContext(context, env)
    return result
  }

  // ===================================================
  // ===================================================
  // COMMON UPDATE FUNCTIONS
  // ===================================================
  // ===================================================
  function emitContext (env, scope, context) {
    var shared = env.shared
    var CONTEXT = shared.context

    var contextEnter = env.scope()

    Object.keys(context).forEach(function (name) {
      scope.save(CONTEXT, '.' + name)
      var defn = context[name]
      var value = defn.append(env, scope)
      if (Array.isArray(value)) {
        contextEnter(CONTEXT, '.', name, '=[', value.join(), '];')
      } else {
        contextEnter(CONTEXT, '.', name, '=', value, ';')
      }
    })

    scope(contextEnter)
  }

  // ===================================================
  // ===================================================
  // COMMON DRAWING FUNCTIONS
  // ===================================================
  // ===================================================
  function emitPollFramebuffer (env, scope, framebuffer, skipCheck) {
    var shared = env.shared

    var GL = shared.gl
    var FRAMEBUFFER_STATE = shared.framebuffer
    var EXT_DRAW_BUFFERS
    if (extDrawBuffers) {
      EXT_DRAW_BUFFERS = scope.def(shared.extensions, '.webgl_draw_buffers')
    }

    var constants = env.constants

    var DRAW_BUFFERS = constants.drawBuffer
    var BACK_BUFFER = constants.backBuffer

    var NEXT
    if (framebuffer) {
      NEXT = framebuffer.append(env, scope)
    } else {
      NEXT = scope.def(FRAMEBUFFER_STATE, '.next')
    }

    if (!skipCheck) {
      scope('if(', NEXT, '!==', FRAMEBUFFER_STATE, '.cur){')
    }
    scope(
      'if(', NEXT, '){',
      GL, '.bindFramebuffer(', GL_FRAMEBUFFER, ',', NEXT, '.framebuffer);')
    if (extDrawBuffers) {
      scope(EXT_DRAW_BUFFERS, '.drawBuffersWEBGL(',
        DRAW_BUFFERS, '[', NEXT, '.colorAttachments.length]);')
    }
    scope('}else{',
      GL, '.bindFramebuffer(', GL_FRAMEBUFFER, ',null);')
    if (extDrawBuffers) {
      scope(EXT_DRAW_BUFFERS, '.drawBuffersWEBGL(', BACK_BUFFER, ');')
    }
    scope(
      '}',
      FRAMEBUFFER_STATE, '.cur=', NEXT, ';')
    if (!skipCheck) {
      scope('}')
    }
  }

  function emitPollState (env, scope, args) {
    var shared = env.shared

    var GL = shared.gl

    var CURRENT_VARS = env.current
    var NEXT_VARS = env.next
    var CURRENT_STATE = shared.current
    var NEXT_STATE = shared.next

    var block = env.cond(CURRENT_STATE, '.dirty')

    GL_STATE_NAMES.forEach(function (prop) {
      var param = propName(prop)
      if (param in args.state) {
        return
      }

      var NEXT, CURRENT
      if (param in NEXT_VARS) {
        NEXT = NEXT_VARS[param]
        CURRENT = CURRENT_VARS[param]
        var parts = loop(currentState[param].length, function (i) {
          return block.def(NEXT, '[', i, ']')
        })
        block(env.cond(parts.map(function (p, i) {
          return p + '!==' + CURRENT + '[' + i + ']'
        }).join('||'))
          .then(
            GL, '.', GL_VARIABLES[param], '(', parts, ');',
            parts.map(function (p, i) {
              return CURRENT + '[' + i + ']=' + p
            }).join(';'), ';'))
      } else {
        NEXT = block.def(NEXT_STATE, '.', param)
        var ifte = env.cond(NEXT, '!==', CURRENT_STATE, '.', param)
        block(ifte)
        if (param in GL_FLAGS) {
          ifte(
            env.cond(NEXT)
              .then(GL, '.enable(', GL_FLAGS[param], ');')
              .else(GL, '.disable(', GL_FLAGS[param], ');'),
            CURRENT_STATE, '.', param, '=', NEXT, ';')
        } else {
          ifte(
            GL, '.', GL_VARIABLES[param], '(', NEXT, ');',
            CURRENT_STATE, '.', param, '=', NEXT, ';')
        }
      }
    })
    if (Object.keys(args.state).length === 0) {
      block(CURRENT_STATE, '.dirty=false;')
    }
    scope(block)
  }

  function emitSetOptions (env, scope, options, filter) {
    var shared = env.shared
    var CURRENT_VARS = env.current
    var CURRENT_STATE = shared.current
    var GL = shared.gl
    sortState(Object.keys(options)).forEach(function (param) {
      var defn = options[param]
      if (filter && !filter(defn)) {
        return
      }
      var variable = defn.append(env, scope)
      if (GL_FLAGS[param]) {
        var flag = GL_FLAGS[param]
        if (isStatic(defn)) {
          if (variable) {
            scope(GL, '.enable(', flag, ');')
          } else {
            scope(GL, '.disable(', flag, ');')
          }
        } else {
          scope(env.cond(variable)
            .then(GL, '.enable(', flag, ');')
            .else(GL, '.disable(', flag, ');'))
        }
        scope(CURRENT_STATE, '.', param, '=', variable, ';')
      } else if (isArrayLike(variable)) {
        var CURRENT = CURRENT_VARS[param]
        scope(
          GL, '.', GL_VARIABLES[param], '(', variable, ');',
          variable.map(function (v, i) {
            return CURRENT + '[' + i + ']=' + v
          }).join(';'), ';')
      } else {
        scope(
          GL, '.', GL_VARIABLES[param], '(', variable, ');',
          CURRENT_STATE, '.', param, '=', variable, ';')
      }
    })
  }

  function injectExtensions (env, scope) {
    if (extInstancing) {
      env.instancing = scope.def(
        env.shared.extensions, '.angle_instanced_arrays')
    }
  }

  function emitProfile (env, scope, args, useScope, incrementCounter) {
    var shared = env.shared
    var STATS = env.stats
    var CURRENT_STATE = shared.current
    var TIMER = shared.timer
    var profileArg = args.profile

    function perfCounter () {
      if (typeof performance === 'undefined') {
        return 'Date.now()'
      } else {
        return 'performance.now()'
      }
    }

    var CPU_START, QUERY_COUNTER
    function emitProfileStart (block) {
      CPU_START = scope.def()
      block(CPU_START, '=', perfCounter(), ';')
      if (typeof incrementCounter === 'string') {
        block(STATS, '.count+=', incrementCounter, ';')
      } else {
        block(STATS, '.count++;')
      }
      if (timer) {
        if (useScope) {
          QUERY_COUNTER = scope.def()
          block(QUERY_COUNTER, '=', TIMER, '.getNumPendingQueries();')
        } else {
          block(TIMER, '.beginQuery(', STATS, ');')
        }
      }
    }

    function emitProfileEnd (block) {
      block(STATS, '.cpuTime+=', perfCounter(), '-', CPU_START, ';')
      if (timer) {
        if (useScope) {
          block(TIMER, '.pushScopeStats(',
            QUERY_COUNTER, ',',
            TIMER, '.getNumPendingQueries(),',
            STATS, ');')
        } else {
          block(TIMER, '.endQuery();')
        }
      }
    }

    function scopeProfile (value) {
      var prev = scope.def(CURRENT_STATE, '.profile')
      scope(CURRENT_STATE, '.profile=', value, ';')
      scope.exit(CURRENT_STATE, '.profile=', prev, ';')
    }

    var USE_PROFILE
    if (profileArg) {
      if (isStatic(profileArg)) {
        if (profileArg.enable) {
          emitProfileStart(scope)
          emitProfileEnd(scope.exit)
          scopeProfile('true')
        } else {
          scopeProfile('false')
        }
        return
      }
      USE_PROFILE = profileArg.append(env, scope)
      scopeProfile(USE_PROFILE)
    } else {
      USE_PROFILE = scope.def(CURRENT_STATE, '.profile')
    }

    var start = env.block()
    emitProfileStart(start)
    scope('if(', USE_PROFILE, '){', start, '}')
    var end = env.block()
    emitProfileEnd(end)
    scope.exit('if(', USE_PROFILE, '){', end, '}')
  }

  function emitAttributes (env, scope, args, attributes, filter) {
    var shared = env.shared

    function typeLength (x) {
      switch (x) {
        case GL_FLOAT_VEC2:
        case GL_INT_VEC2:
        case GL_BOOL_VEC2:
          return 2
        case GL_FLOAT_VEC3:
        case GL_INT_VEC3:
        case GL_BOOL_VEC3:
          return 3
        case GL_FLOAT_VEC4:
        case GL_INT_VEC4:
        case GL_BOOL_VEC4:
          return 4
        default:
          return 1
      }
    }

    function emitBindAttribute (ATTRIBUTE, size, record) {
      var GL = shared.gl

      var LOCATION = scope.def(ATTRIBUTE, '.location')
      var BINDING = scope.def(shared.attributes, '[', LOCATION, ']')

      var STATE = record.state
      var BUFFER = record.buffer
      var CONST_COMPONENTS = [
        record.x,
        record.y,
        record.z,
        record.w
      ]

      var COMMON_KEYS = [
        'buffer',
        'normalized',
        'offset',
        'stride'
      ]

      function emitBuffer () {
        scope(
          'if(!', BINDING, '.buffer){',
          GL, '.enableVertexAttribArray(', LOCATION, ');}')

        var TYPE = record.type
        var SIZE
        if (!record.size) {
          SIZE = size
        } else {
          SIZE = scope.def(record.size, '||', size)
        }

        scope('if(',
          BINDING, '.type!==', TYPE, '||',
          BINDING, '.size!==', SIZE, '||',
          COMMON_KEYS.map(function (key) {
            return BINDING + '.' + key + '!==' + record[key]
          }).join('||'),
          '){',
          GL, '.bindBuffer(', GL_ARRAY_BUFFER, ',', BUFFER, '.buffer);',
          GL, '.vertexAttribPointer(', [
            LOCATION,
            SIZE,
            TYPE,
            record.normalized,
            record.stride,
            record.offset
          ], ');',
          BINDING, '.type=', TYPE, ';',
          BINDING, '.size=', SIZE, ';',
          COMMON_KEYS.map(function (key) {
            return BINDING + '.' + key + '=' + record[key] + ';'
          }).join(''),
          '}')

        if (extInstancing) {
          var DIVISOR = record.divisor
          scope(
            'if(', BINDING, '.divisor!==', DIVISOR, '){',
            env.instancing, '.vertexAttribDivisorANGLE(', [LOCATION, DIVISOR], ');',
            BINDING, '.divisor=', DIVISOR, ';}')
        }
      }

      function emitConstant () {
        scope(
          'if(', BINDING, '.buffer){',
          GL, '.disableVertexAttribArray(', LOCATION, ');',
          BINDING, '.buffer=null;',
          '}if(', CUTE_COMPONENTS.map(function (c, i) {
            return BINDING + '.' + c + '!==' + CONST_COMPONENTS[i]
          }).join('||'), '){',
          GL, '.vertexAttrib4f(', LOCATION, ',', CONST_COMPONENTS, ');',
          CUTE_COMPONENTS.map(function (c, i) {
            return BINDING + '.' + c + '=' + CONST_COMPONENTS[i] + ';'
          }).join(''),
          '}')
      }

      if (STATE === ATTRIB_STATE_POINTER) {
        emitBuffer()
      } else if (STATE === ATTRIB_STATE_CONSTANT) {
        emitConstant()
      } else {
        scope('if(', STATE, '===', ATTRIB_STATE_POINTER, '){')
        emitBuffer()
        scope('}else{')
        emitConstant()
        scope('}')
      }
    }

    attributes.forEach(function (attribute) {
      var name = attribute.name
      var arg = args.attributes[name]
      var record
      if (arg) {
        if (!filter(arg)) {
          return
        }
        record = arg.append(env, scope)
      } else {
        if (!filter(SCOPE_DECL)) {
          return
        }
        var scopeAttrib = env.scopeAttrib(name)
        check.optional(function () {
          env.assert(scope,
            scopeAttrib + '.state',
            'missing attribute ' + name)
        })
        record = {}
        Object.keys(new AttributeRecord()).forEach(function (key) {
          record[key] = scope.def(scopeAttrib, '.', key)
        })
      }
      emitBindAttribute(
        env.link(attribute), typeLength(attribute.info.type), record)
    })
  }

  function emitUniforms (env, scope, args, uniforms, filter, isBatchInnerLoop) {
    var shared = env.shared
    var GL = shared.gl

    var definedArrUniforms = {}
    var infix
    for (var i = 0; i < uniforms.length; ++i) {
      var uniform = uniforms[i]
      var name = uniform.name
      var type = uniform.info.type
      var size = uniform.info.size
      var arg = args.uniforms[name]
      if (size > 1) {
        // either foo[n] or foos, avoid define both
        if (!arg) {
          continue
        }
        var arrUniformName = name.replace('[0]', '')
        if (definedArrUniforms[arrUniformName]) {
          continue
        }
        definedArrUniforms[arrUniformName] = 1
      }
      var UNIFORM = env.link(uniform)
      var LOCATION = UNIFORM + '.location'

      var VALUE
      if (arg) {
        if (!filter(arg)) {
          continue
        }
        if (isStatic(arg)) {
          var value = arg.value
          check.command(
            value !== null && typeof value !== 'undefined',
            'missing uniform "' + name + '"', env.commandStr)
          if (type === GL_SAMPLER_2D || type === GL_SAMPLER_CUBE) {
            check.command(
              typeof value === 'function' &&
              ((type === GL_SAMPLER_2D &&
                (value._reglType === 'texture2d' ||
                value._reglType === 'framebuffer')) ||
              (type === GL_SAMPLER_CUBE &&
                (value._reglType === 'textureCube' ||
                value._reglType === 'framebufferCube'))),
              'invalid texture for uniform ' + name, env.commandStr)
            var TEX_VALUE = env.link(value._texture || value.color[0]._texture)
            scope(GL, '.uniform1i(', LOCATION, ',', TEX_VALUE + '.bind());')
            scope.exit(TEX_VALUE, '.unbind();')
          } else if (
            type === GL_FLOAT_MAT2 ||
            type === GL_FLOAT_MAT3 ||
            type === GL_FLOAT_MAT4) {
            check.optional(function () {
              check.command(isArrayLike(value),
                'invalid matrix for uniform ' + name, env.commandStr)
              check.command(
                (type === GL_FLOAT_MAT2 && value.length === 4) ||
                (type === GL_FLOAT_MAT3 && value.length === 9) ||
                (type === GL_FLOAT_MAT4 && value.length === 16),
                'invalid length for matrix uniform ' + name, env.commandStr)
            })
            var MAT_VALUE = env.global.def('new Float32Array([' +
              Array.prototype.slice.call(value) + '])')
            var dim = 2
            if (type === GL_FLOAT_MAT3) {
              dim = 3
            } else if (type === GL_FLOAT_MAT4) {
              dim = 4
            }
            scope(
              GL, '.uniformMatrix', dim, 'fv(',
              LOCATION, ',false,', MAT_VALUE, ');')
          } else {
            switch (type) {
              case GL_FLOAT:
                if (size === 1) {
                  check.commandType(value, 'number', 'uniform ' + name, env.commandStr)
                } else {
                  check.command(
                    isArrayLike(value) && (value.length === size),
                    'uniform ' + name, env.commandStr)
                }
                infix = '1f'
                break
              case GL_FLOAT_VEC2:
                check.command(
                  isArrayLike(value) && (value.length && value.length % 2 === 0 && value.length <= size * 2),
                  'uniform ' + name, env.commandStr)
                infix = '2f'
                break
              case GL_FLOAT_VEC3:
                check.command(
                  isArrayLike(value) && (value.length && value.length % 3 === 0 && value.length <= size * 3),
                  'uniform ' + name, env.commandStr)
                infix = '3f'
                break
              case GL_FLOAT_VEC4:
                check.command(
                  isArrayLike(value) && (value.length && value.length % 4 === 0 && value.length <= size * 4),
                  'uniform ' + name, env.commandStr)
                infix = '4f'
                break
              case GL_BOOL:
                if (size === 1) {
                  check.commandType(value, 'boolean', 'uniform ' + name, env.commandStr)
                } else {
                  check.command(
                    isArrayLike(value) && (value.length === size),
                    'uniform ' + name, env.commandStr)
                }
                infix = '1i'
                break
              case GL_INT:
                if (size === 1) {
                  check.commandType(value, 'number', 'uniform ' + name, env.commandStr)
                } else {
                  check.command(
                    isArrayLike(value) && (value.length === size),
                    'uniform ' + name, env.commandStr)
                }
                infix = '1i'
                break
              case GL_BOOL_VEC2:
                check.command(
                  isArrayLike(value) && (value.length && value.length % 2 === 0 && value.length <= size * 2),
                  'uniform ' + name, env.commandStr)
                infix = '2i'
                break
              case GL_INT_VEC2:
                check.command(
                  isArrayLike(value) && (value.length && value.length % 2 === 0 && value.length <= size * 2),
                  'uniform ' + name, env.commandStr)
                infix = '2i'
                break
              case GL_BOOL_VEC3:
                check.command(
                  isArrayLike(value) && (value.length && value.length % 3 === 0 && value.length <= size * 3),
                  'uniform ' + name, env.commandStr)
                infix = '3i'
                break
              case GL_INT_VEC3:
                check.command(
                  isArrayLike(value) && (value.length && value.length % 3 === 0 && value.length <= size * 3),
                  'uniform ' + name, env.commandStr)
                infix = '3i'
                break
              case GL_BOOL_VEC4:
                check.command(
                  isArrayLike(value) && (value.length && value.length % 4 === 0 && value.length <= size * 4),
                  'uniform ' + name, env.commandStr)
                infix = '4i'
                break
              case GL_INT_VEC4:
                check.command(
                  isArrayLike(value) && (value.length && value.length % 4 === 0 && value.length <= size * 4),
                  'uniform ' + name, env.commandStr)
                infix = '4i'
                break
            }
            if (size > 1) {
              infix += 'v'
              value = env.global.def('[' +
              Array.prototype.slice.call(value) + ']')
            } else {
              value = isArrayLike(value) ? Array.prototype.slice.call(value) : value
            }
            scope(GL, '.uniform', infix, '(', LOCATION, ',',
              value,
              ');')
          }
          continue
        } else {
          VALUE = arg.append(env, scope)
        }
      } else {
        if (!filter(SCOPE_DECL)) {
          continue
        }
        VALUE = scope.def(shared.uniforms, '[', stringStore.id(name), ']')
      }

      if (type === GL_SAMPLER_2D) {
        check(!Array.isArray(VALUE), 'must specify a scalar prop for textures')
        scope(
          'if(', VALUE, '&&', VALUE, '._reglType==="framebuffer"){',
          VALUE, '=', VALUE, '.color[0];',
          '}')
      } else if (type === GL_SAMPLER_CUBE) {
        check(!Array.isArray(VALUE), 'must specify a scalar prop for cube maps')
        scope(
          'if(', VALUE, '&&', VALUE, '._reglType==="framebufferCube"){',
          VALUE, '=', VALUE, '.color[0];',
          '}')
      }

      // perform type validation
      check.optional(function () {
        function emitCheck (pred, message) {
          env.assert(scope, pred,
            'bad data or missing for uniform "' + name + '".  ' + message)
        }

        function checkType (type, size) {
          if (size === 1) {
            check(!Array.isArray(VALUE), 'must not specify an array type for uniform')
          }
          emitCheck(
            'Array.isArray(' + VALUE + ') && typeof ' + VALUE + '[0]===" ' + type + '"' +
            ' || typeof ' + VALUE + '==="' + type + '"',
            'invalid type, expected ' + type)
        }

        function checkVector (n, type, size) {
          if (Array.isArray(VALUE)) {
            check(VALUE.length && VALUE.length % n === 0 && VALUE.length <= n * size, 'must have length of ' + (size === 1 ? '' : 'n * ') + n)
          } else {
            emitCheck(
              shared.isArrayLike + '(' + VALUE + ')&&' + VALUE + '.length && ' + VALUE + '.length % ' + n + ' === 0' +
              ' && ' + VALUE + '.length<=' + n * size,
              'invalid vector, should have length of ' + (size === 1 ? '' : 'n * ') + n, env.commandStr)
          }
        }

        function checkTexture (target) {
          check(!Array.isArray(VALUE), 'must not specify a value type')
          emitCheck(
            'typeof ' + VALUE + '==="function"&&' +
            VALUE + '._reglType==="texture' +
            (target === GL_TEXTURE_2D ? '2d' : 'Cube') + '"',
            'invalid texture type', env.commandStr)
        }

        switch (type) {
          case GL_INT:
            checkType('number', size)
            break
          case GL_INT_VEC2:
            checkVector(2, 'number', size)
            break
          case GL_INT_VEC3:
            checkVector(3, 'number', size)
            break
          case GL_INT_VEC4:
            checkVector(4, 'number', size)
            break
          case GL_FLOAT:
            checkType('number', size)
            break
          case GL_FLOAT_VEC2:
            checkVector(2, 'number', size)
            break
          case GL_FLOAT_VEC3:
            checkVector(3, 'number', size)
            break
          case GL_FLOAT_VEC4:
            checkVector(4, 'number', size)
            break
          case GL_BOOL:
            checkType('boolean', size)
            break
          case GL_BOOL_VEC2:
            checkVector(2, 'boolean', size)
            break
          case GL_BOOL_VEC3:
            checkVector(3, 'boolean', size)
            break
          case GL_BOOL_VEC4:
            checkVector(4, 'boolean', size)
            break
          case GL_FLOAT_MAT2:
            checkVector(4, 'number', size)
            break
          case GL_FLOAT_MAT3:
            checkVector(9, 'number', size)
            break
          case GL_FLOAT_MAT4:
            checkVector(16, 'number', size)
            break
          case GL_SAMPLER_2D:
            checkTexture(GL_TEXTURE_2D)
            break
          case GL_SAMPLER_CUBE:
            checkTexture(GL_TEXTURE_CUBE_MAP)
            break
        }
      })

      var unroll = 1
      switch (type) {
        case GL_SAMPLER_2D:
        case GL_SAMPLER_CUBE:
          var TEX = scope.def(VALUE, '._texture')
          scope(GL, '.uniform1i(', LOCATION, ',', TEX, '.bind());')
          scope.exit(TEX, '.unbind();')
          continue

        case GL_INT:
        case GL_BOOL:
          infix = '1i'
          break

        case GL_INT_VEC2:
        case GL_BOOL_VEC2:
          infix = '2i'
          unroll = 2
          break

        case GL_INT_VEC3:
        case GL_BOOL_VEC3:
          infix = '3i'
          unroll = 3
          break

        case GL_INT_VEC4:
        case GL_BOOL_VEC4:
          infix = '4i'
          unroll = 4
          break

        case GL_FLOAT:
          infix = '1f'
          break

        case GL_FLOAT_VEC2:
          infix = '2f'
          unroll = 2
          break

        case GL_FLOAT_VEC3:
          infix = '3f'
          unroll = 3
          break

        case GL_FLOAT_VEC4:
          infix = '4f'
          unroll = 4
          break

        case GL_FLOAT_MAT2:
          infix = 'Matrix2fv'
          break

        case GL_FLOAT_MAT3:
          infix = 'Matrix3fv'
          break

        case GL_FLOAT_MAT4:
          infix = 'Matrix4fv'
          break
      }

      if (infix.indexOf('Matrix') === -1 && size > 1) {
        infix += 'v'
        unroll = 1
      }

      if (infix.charAt(0) === 'M') {
        scope(GL, '.uniform', infix, '(', LOCATION, ',')
        var matSize = Math.pow(type - GL_FLOAT_MAT2 + 2, 2)
        var STORAGE = env.global.def('new Float32Array(', matSize, ')')
        if (Array.isArray(VALUE)) {
          scope(
            'false,(',
            loop(matSize, function (i) {
              return STORAGE + '[' + i + ']=' + VALUE[i]
            }), ',', STORAGE, ')')
        } else {
          scope(
            'false,(Array.isArray(', VALUE, ')||', VALUE, ' instanceof Float32Array)?', VALUE, ':(',
            loop(matSize, function (i) {
              return STORAGE + '[' + i + ']=' + VALUE + '[' + i + ']'
            }), ',', STORAGE, ')')
        }
        scope(');')
      } else if (unroll > 1) {
        var prev = []
        var cur = []
        for (var j = 0; j < unroll; ++j) {
          if (Array.isArray(VALUE)) {
            cur.push(VALUE[j])
          } else {
            cur.push(scope.def(VALUE + '[' + j + ']'))
          }
          if (isBatchInnerLoop) {
            prev.push(scope.def())
          }
        }
        if (isBatchInnerLoop) {
          scope('if(!', env.batchId, '||', prev.map(function (p, i) {
            return p + '!==' + cur[i]
          }).join('||'), '){', prev.map(function (p, i) {
            return p + '=' + cur[i] + ';'
          }).join(''))
        }
        scope(GL, '.uniform', infix, '(', LOCATION, ',', cur.join(','), ');')
        if (isBatchInnerLoop) {
          scope('}')
        }
      } else {
        check(!Array.isArray(VALUE), 'uniform value must not be an array')
        if (isBatchInnerLoop) {
          var prevS = scope.def()
          scope('if(!', env.batchId, '||', prevS, '!==', VALUE, '){',
            prevS, '=', VALUE, ';')
        }
        scope(GL, '.uniform', infix, '(', LOCATION, ',', VALUE, ');')
        if (isBatchInnerLoop) {
          scope('}')
        }
      }
    }
  }

  function emitDraw (env, outer, inner, args) {
    var shared = env.shared
    var GL = shared.gl
    var DRAW_STATE = shared.draw

    var drawOptions = args.draw

    function emitElements () {
      var defn = drawOptions.elements
      var ELEMENTS
      var scope = outer
      if (defn) {
        if ((defn.contextDep && args.contextDynamic) || defn.propDep) {
          scope = inner
        }
        ELEMENTS = defn.append(env, scope)
        if (drawOptions.elementsActive) {
          scope(
            'if(' + ELEMENTS + ')' +
            GL + '.bindBuffer(' + GL_ELEMENT_ARRAY_BUFFER + ',' + ELEMENTS + '.buffer.buffer);')
        }
      } else {
        ELEMENTS = scope.def()
        scope(
          ELEMENTS, '=', DRAW_STATE, '.', S_ELEMENTS, ';',
          'if(', ELEMENTS, '){',
          GL, '.bindBuffer(', GL_ELEMENT_ARRAY_BUFFER, ',', ELEMENTS, '.buffer.buffer);}',
          'else if(', shared.vao, '.currentVAO){',
          ELEMENTS, '=', env.shared.elements + '.getElements(' + shared.vao, '.currentVAO.elements);',
          (!extVertexArrays ? 'if(' + ELEMENTS + ')' + GL + '.bindBuffer(' + GL_ELEMENT_ARRAY_BUFFER + ',' + ELEMENTS + '.buffer.buffer);' : ''),
          '}')
      }
      return ELEMENTS
    }

    function emitCount () {
      var defn = drawOptions.count
      var COUNT
      var scope = outer
      if (defn) {
        if ((defn.contextDep && args.contextDynamic) || defn.propDep) {
          scope = inner
        }
        COUNT = defn.append(env, scope)
        check.optional(function () {
          if (defn.MISSING) {
            env.assert(outer, 'false', 'missing vertex count')
          }
          if (defn.DYNAMIC) {
            env.assert(scope, COUNT + '>=0', 'missing vertex count')
          }
        })
      } else {
        COUNT = scope.def(DRAW_STATE, '.', S_COUNT)
        check.optional(function () {
          env.assert(scope, COUNT + '>=0', 'missing vertex count')
        })
      }
      return COUNT
    }

    var ELEMENTS = emitElements()
    function emitValue (name) {
      var defn = drawOptions[name]
      if (defn) {
        if ((defn.contextDep && args.contextDynamic) || defn.propDep) {
          return defn.append(env, inner)
        } else {
          return defn.append(env, outer)
        }
      } else {
        return outer.def(DRAW_STATE, '.', name)
      }
    }

    var PRIMITIVE = emitValue(S_PRIMITIVE)
    var OFFSET = emitValue(S_OFFSET)

    var COUNT = emitCount()
    if (typeof COUNT === 'number') {
      if (COUNT === 0) {
        return
      }
    } else {
      inner('if(', COUNT, '){')
      inner.exit('}')
    }

    var INSTANCES, EXT_INSTANCING
    if (extInstancing) {
      INSTANCES = emitValue(S_INSTANCES)
      EXT_INSTANCING = env.instancing
    }

    var ELEMENT_TYPE = ELEMENTS + '.type'

    var elementsStatic = drawOptions.elements && isStatic(drawOptions.elements) && !drawOptions.vaoActive

    function emitInstancing () {
      function drawElements () {
        inner(EXT_INSTANCING, '.drawElementsInstancedANGLE(', [
          PRIMITIVE,
          COUNT,
          ELEMENT_TYPE,
          OFFSET + '<<((' + ELEMENT_TYPE + '-' + GL_UNSIGNED_BYTE + ')>>1)',
          INSTANCES
        ], ');')
      }

      function drawArrays () {
        inner(EXT_INSTANCING, '.drawArraysInstancedANGLE(',
          [PRIMITIVE, OFFSET, COUNT, INSTANCES], ');')
      }

      if (ELEMENTS && ELEMENTS !== 'null') {
        if (!elementsStatic) {
          inner('if(', ELEMENTS, '){')
          drawElements()
          inner('}else{')
          drawArrays()
          inner('}')
        } else {
          drawElements()
        }
      } else {
        drawArrays()
      }
    }

    function emitRegular () {
      function drawElements () {
        inner(GL + '.drawElements(' + [
          PRIMITIVE,
          COUNT,
          ELEMENT_TYPE,
          OFFSET + '<<((' + ELEMENT_TYPE + '-' + GL_UNSIGNED_BYTE + ')>>1)'
        ] + ');')
      }

      function drawArrays () {
        inner(GL + '.drawArrays(' + [PRIMITIVE, OFFSET, COUNT] + ');')
      }

      if (ELEMENTS && ELEMENTS !== 'null') {
        if (!elementsStatic) {
          inner('if(', ELEMENTS, '){')
          drawElements()
          inner('}else{')
          drawArrays()
          inner('}')
        } else {
          drawElements()
        }
      } else {
        drawArrays()
      }
    }

    if (extInstancing && (typeof INSTANCES !== 'number' || INSTANCES >= 0)) {
      if (typeof INSTANCES === 'string') {
        inner('if(', INSTANCES, '>0){')
        emitInstancing()
        inner('}else if(', INSTANCES, '<0){')
        emitRegular()
        inner('}')
      } else {
        emitInstancing()
      }
    } else {
      emitRegular()
    }
  }

  function createBody (emitBody, parentEnv, args, program, count) {
    var env = createREGLEnvironment()
    var scope = env.proc('body', count)
    check.optional(function () {
      env.commandStr = parentEnv.commandStr
      env.command = env.link(parentEnv.commandStr)
    })
    if (extInstancing) {
      env.instancing = scope.def(
        env.shared.extensions, '.angle_instanced_arrays')
    }
    emitBody(env, scope, args, program)
    return env.compile().body
  }

  // ===================================================
  // ===================================================
  // DRAW PROC
  // ===================================================
  // ===================================================
  function emitDrawBody (env, draw, args, program) {
    injectExtensions(env, draw)
    if (args.useVAO) {
      if (args.drawVAO) {
        draw(env.shared.vao, '.setVAO(', args.drawVAO.append(env, draw), ');')
      } else {
        draw(env.shared.vao, '.setVAO(', env.shared.vao, '.targetVAO);')
      }
    } else {
      draw(env.shared.vao, '.setVAO(null);')
      emitAttributes(env, draw, args, program.attributes, function () {
        return true
      })
    }
    emitUniforms(env, draw, args, program.uniforms, function () {
      return true
    }, false)
    emitDraw(env, draw, draw, args)
  }

  function emitDrawProc (env, args) {
    var draw = env.proc('draw', 1)

    injectExtensions(env, draw)

    emitContext(env, draw, args.context)
    emitPollFramebuffer(env, draw, args.framebuffer)

    emitPollState(env, draw, args)
    emitSetOptions(env, draw, args.state)

    emitProfile(env, draw, args, false, true)

    var program = args.shader.progVar.append(env, draw)
    draw(env.shared.gl, '.useProgram(', program, '.program);')

    if (args.shader.program) {
      emitDrawBody(env, draw, args, args.shader.program)
    } else {
      draw(env.shared.vao, '.setVAO(null);')
      var drawCache = env.global.def('{}')
      var PROG_ID = draw.def(program, '.id')
      var CACHED_PROC = draw.def(drawCache, '[', PROG_ID, ']')
      draw(
        env.cond(CACHED_PROC)
          .then(CACHED_PROC, '.call(this,a0);')
          .else(
            CACHED_PROC, '=', drawCache, '[', PROG_ID, ']=',
            env.link(function (program) {
              return createBody(emitDrawBody, env, args, program, 1)
            }), '(', program, ');',
            CACHED_PROC, '.call(this,a0);'))
    }

    if (Object.keys(args.state).length > 0) {
      draw(env.shared.current, '.dirty=true;')
    }
    if (env.shared.vao) {
      draw(env.shared.vao, '.setVAO(null);')
    }
  }

  // ===================================================
  // ===================================================
  // BATCH PROC
  // ===================================================
  // ===================================================

  function emitBatchDynamicShaderBody (env, scope, args, program) {
    env.batchId = 'a1'

    injectExtensions(env, scope)

    function all () {
      return true
    }

    emitAttributes(env, scope, args, program.attributes, all)
    emitUniforms(env, scope, args, program.uniforms, all, false)
    emitDraw(env, scope, scope, args)
  }

  function emitBatchBody (env, scope, args, program) {
    injectExtensions(env, scope)

    var contextDynamic = args.contextDep

    var BATCH_ID = scope.def()
    var PROP_LIST = 'a0'
    var NUM_PROPS = 'a1'
    var PROPS = scope.def()
    env.shared.props = PROPS
    env.batchId = BATCH_ID

    var outer = env.scope()
    var inner = env.scope()

    scope(
      outer.entry,
      'for(', BATCH_ID, '=0;', BATCH_ID, '<', NUM_PROPS, ';++', BATCH_ID, '){',
      PROPS, '=', PROP_LIST, '[', BATCH_ID, '];',
      inner,
      '}',
      outer.exit)

    function isInnerDefn (defn) {
      return ((defn.contextDep && contextDynamic) || defn.propDep)
    }

    function isOuterDefn (defn) {
      return !isInnerDefn(defn)
    }

    if (args.needsContext) {
      emitContext(env, inner, args.context)
    }
    if (args.needsFramebuffer) {
      emitPollFramebuffer(env, inner, args.framebuffer)
    }
    emitSetOptions(env, inner, args.state, isInnerDefn)

    if (args.profile && isInnerDefn(args.profile)) {
      emitProfile(env, inner, args, false, true)
    }

    if (!program) {
      var progCache = env.global.def('{}')
      var PROGRAM = args.shader.progVar.append(env, inner)
      var PROG_ID = inner.def(PROGRAM, '.id')
      var CACHED_PROC = inner.def(progCache, '[', PROG_ID, ']')
      inner(
        env.shared.gl, '.useProgram(', PROGRAM, '.program);',
        'if(!', CACHED_PROC, '){',
        CACHED_PROC, '=', progCache, '[', PROG_ID, ']=',
        env.link(function (program) {
          return createBody(
            emitBatchDynamicShaderBody, env, args, program, 2)
        }), '(', PROGRAM, ');}',
        CACHED_PROC, '.call(this,a0[', BATCH_ID, '],', BATCH_ID, ');')
    } else {
      if (args.useVAO) {
        if (args.drawVAO) {
          if (isInnerDefn(args.drawVAO)) {
            // vao is a prop
            inner(env.shared.vao, '.setVAO(', args.drawVAO.append(env, inner), ');')
          } else {
            // vao is invariant
            outer(env.shared.vao, '.setVAO(', args.drawVAO.append(env, outer), ');')
          }
        } else {
          // scoped vao binding
          outer(env.shared.vao, '.setVAO(', env.shared.vao, '.targetVAO);')
        }
      } else {
        outer(env.shared.vao, '.setVAO(null);')
        emitAttributes(env, outer, args, program.attributes, isOuterDefn)
        emitAttributes(env, inner, args, program.attributes, isInnerDefn)
      }
      emitUniforms(env, outer, args, program.uniforms, isOuterDefn, false)
      emitUniforms(env, inner, args, program.uniforms, isInnerDefn, true)
      emitDraw(env, outer, inner, args)
    }
  }

  function emitBatchProc (env, args) {
    var batch = env.proc('batch', 2)
    env.batchId = '0'

    injectExtensions(env, batch)

    // Check if any context variables depend on props
    var contextDynamic = false
    var needsContext = true
    Object.keys(args.context).forEach(function (name) {
      contextDynamic = contextDynamic || args.context[name].propDep
    })
    if (!contextDynamic) {
      emitContext(env, batch, args.context)
      needsContext = false
    }

    // framebuffer state affects framebufferWidth/height context vars
    var framebuffer = args.framebuffer
    var needsFramebuffer = false
    if (framebuffer) {
      if (framebuffer.propDep) {
        contextDynamic = needsFramebuffer = true
      } else if (framebuffer.contextDep && contextDynamic) {
        needsFramebuffer = true
      }
      if (!needsFramebuffer) {
        emitPollFramebuffer(env, batch, framebuffer)
      }
    } else {
      emitPollFramebuffer(env, batch, null)
    }

    // viewport is weird because it can affect context vars
    if (args.state.viewport && args.state.viewport.propDep) {
      contextDynamic = true
    }

    function isInnerDefn (defn) {
      return (defn.contextDep && contextDynamic) || defn.propDep
    }

    // set webgl options
    emitPollState(env, batch, args)
    emitSetOptions(env, batch, args.state, function (defn) {
      return !isInnerDefn(defn)
    })

    if (!args.profile || !isInnerDefn(args.profile)) {
      emitProfile(env, batch, args, false, 'a1')
    }

    // Save these values to args so that the batch body routine can use them
    args.contextDep = contextDynamic
    args.needsContext = needsContext
    args.needsFramebuffer = needsFramebuffer

    // determine if shader is dynamic
    var progDefn = args.shader.progVar
    if ((progDefn.contextDep && contextDynamic) || progDefn.propDep) {
      emitBatchBody(
        env,
        batch,
        args,
        null)
    } else {
      var PROGRAM = progDefn.append(env, batch)
      batch(env.shared.gl, '.useProgram(', PROGRAM, '.program);')
      if (args.shader.program) {
        emitBatchBody(
          env,
          batch,
          args,
          args.shader.program)
      } else {
        batch(env.shared.vao, '.setVAO(null);')
        var batchCache = env.global.def('{}')
        var PROG_ID = batch.def(PROGRAM, '.id')
        var CACHED_PROC = batch.def(batchCache, '[', PROG_ID, ']')
        batch(
          env.cond(CACHED_PROC)
            .then(CACHED_PROC, '.call(this,a0,a1);')
            .else(
              CACHED_PROC, '=', batchCache, '[', PROG_ID, ']=',
              env.link(function (program) {
                return createBody(emitBatchBody, env, args, program, 2)
              }), '(', PROGRAM, ');',
              CACHED_PROC, '.call(this,a0,a1);'))
      }
    }

    if (Object.keys(args.state).length > 0) {
      batch(env.shared.current, '.dirty=true;')
    }

    if (env.shared.vao) {
      batch(env.shared.vao, '.setVAO(null);')
    }
  }

  // ===================================================
  // ===================================================
  // SCOPE COMMAND
  // ===================================================
  // ===================================================
  function emitScopeProc (env, args) {
    var scope = env.proc('scope', 3)
    env.batchId = 'a2'

    var shared = env.shared
    var CURRENT_STATE = shared.current

    emitContext(env, scope, args.context)

    if (args.framebuffer) {
      args.framebuffer.append(env, scope)
    }

    sortState(Object.keys(args.state)).forEach(function (name) {
      var defn = args.state[name]
      var value = defn.append(env, scope)
      if (isArrayLike(value)) {
        value.forEach(function (v, i) {
          scope.set(env.next[name], '[' + i + ']', v)
        })
      } else {
        scope.set(shared.next, '.' + name, value)
      }
    })

    emitProfile(env, scope, args, true, true)

    ;[S_ELEMENTS, S_OFFSET, S_COUNT, S_INSTANCES, S_PRIMITIVE].forEach(
      function (opt) {
        var variable = args.draw[opt]
        if (!variable) {
          return
        }
        scope.set(shared.draw, '.' + opt, '' + variable.append(env, scope))
      })

    Object.keys(args.uniforms).forEach(function (opt) {
      var value = args.uniforms[opt].append(env, scope)
      if (Array.isArray(value)) {
        value = '[' + value.join() + ']'
      }
      scope.set(
        shared.uniforms,
        '[' + stringStore.id(opt) + ']',
        value)
    })

    Object.keys(args.attributes).forEach(function (name) {
      var record = args.attributes[name].append(env, scope)
      var scopeAttrib = env.scopeAttrib(name)
      Object.keys(new AttributeRecord()).forEach(function (prop) {
        scope.set(scopeAttrib, '.' + prop, record[prop])
      })
    })

    if (args.scopeVAO) {
      scope.set(shared.vao, '.targetVAO', args.scopeVAO.append(env, scope))
    }

    function saveShader (name) {
      var shader = args.shader[name]
      if (shader) {
        scope.set(shared.shader, '.' + name, shader.append(env, scope))
      }
    }
    saveShader(S_VERT)
    saveShader(S_FRAG)

    if (Object.keys(args.state).length > 0) {
      scope(CURRENT_STATE, '.dirty=true;')
      scope.exit(CURRENT_STATE, '.dirty=true;')
    }

    scope('a1(', env.shared.context, ',a0,', env.batchId, ');')
  }

  function isDynamicObject (object) {
    if (typeof object !== 'object' || isArrayLike(object)) {
      return
    }
    var props = Object.keys(object)
    for (var i = 0; i < props.length; ++i) {
      if (dynamic.isDynamic(object[props[i]])) {
        return true
      }
    }
    return false
  }

  function splatObject (env, options, name) {
    var object = options.static[name]
    if (!object || !isDynamicObject(object)) {
      return
    }

    var globals = env.global
    var keys = Object.keys(object)
    var thisDep = false
    var contextDep = false
    var propDep = false
    var objectRef = env.global.def('{}')
    keys.forEach(function (key) {
      var value = object[key]
      if (dynamic.isDynamic(value)) {
        if (typeof value === 'function') {
          value = object[key] = dynamic.unbox(value)
        }
        var deps = createDynamicDecl(value, null)
        thisDep = thisDep || deps.thisDep
        propDep = propDep || deps.propDep
        contextDep = contextDep || deps.contextDep
      } else {
        globals(objectRef, '.', key, '=')
        switch (typeof value) {
          case 'number':
            globals(value)
            break
          case 'string':
            globals('"', value, '"')
            break
          case 'object':
            if (Array.isArray(value)) {
              globals('[', value.join(), ']')
            }
            break
          default:
            globals(env.link(value))
            break
        }
        globals(';')
      }
    })

    function appendBlock (env, block) {
      keys.forEach(function (key) {
        var value = object[key]
        if (!dynamic.isDynamic(value)) {
          return
        }
        var ref = env.invoke(block, value)
        block(objectRef, '.', key, '=', ref, ';')
      })
    }

    options.dynamic[name] = new dynamic.DynamicVariable(DYN_THUNK, {
      thisDep: thisDep,
      contextDep: contextDep,
      propDep: propDep,
      ref: objectRef,
      append: appendBlock
    })
    delete options.static[name]
  }

  // ===========================================================================
  // ===========================================================================
  // MAIN DRAW COMMAND
  // ===========================================================================
  // ===========================================================================
  function compileCommand (options, attributes, uniforms, context, stats) {
    var env = createREGLEnvironment()

    // link stats, so that we can easily access it in the program.
    env.stats = env.link(stats)

    // splat options and attributes to allow for dynamic nested properties
    Object.keys(attributes.static).forEach(function (key) {
      splatObject(env, attributes, key)
    })
    NESTED_OPTIONS.forEach(function (name) {
      splatObject(env, options, name)
    })

    var args = parseArguments(options, attributes, uniforms, context, env)

    emitDrawProc(env, args)
    emitScopeProc(env, args)
    emitBatchProc(env, args)

    return extend(env.compile(), {
      destroy: function () {
        args.shader.program.destroy()
      }
    })
  }

  // ===========================================================================
  // ===========================================================================
  // POLL / REFRESH
  // ===========================================================================
  // ===========================================================================
  return {
    next: nextState,
    current: currentState,
    procs: (function () {
      var env = createREGLEnvironment()
      var poll = env.proc('poll')
      var refresh = env.proc('refresh')
      var common = env.block()
      poll(common)
      refresh(common)

      var shared = env.shared
      var GL = shared.gl
      var NEXT_STATE = shared.next
      var CURRENT_STATE = shared.current

      common(CURRENT_STATE, '.dirty=false;')

      emitPollFramebuffer(env, poll)
      emitPollFramebuffer(env, refresh, null, true)

      // Refresh updates all attribute state changes
      var INSTANCING
      if (extInstancing) {
        INSTANCING = env.link(extInstancing)
      }

      // update vertex array bindings
      if (extensions.oes_vertex_array_object) {
        refresh(env.link(extensions.oes_vertex_array_object), '.bindVertexArrayOES(null);')
      }
      for (var i = 0; i < limits.maxAttributes; ++i) {
        var BINDING = refresh.def(shared.attributes, '[', i, ']')
        var ifte = env.cond(BINDING, '.buffer')
        ifte.then(
          GL, '.enableVertexAttribArray(', i, ');',
          GL, '.bindBuffer(',
          GL_ARRAY_BUFFER, ',',
          BINDING, '.buffer.buffer);',
          GL, '.vertexAttribPointer(',
          i, ',',
          BINDING, '.size,',
          BINDING, '.type,',
          BINDING, '.normalized,',
          BINDING, '.stride,',
          BINDING, '.offset);'
        ).else(
          GL, '.disableVertexAttribArray(', i, ');',
          GL, '.vertexAttrib4f(',
          i, ',',
          BINDING, '.x,',
          BINDING, '.y,',
          BINDING, '.z,',
          BINDING, '.w);',
          BINDING, '.buffer=null;')
        refresh(ifte)
        if (extInstancing) {
          refresh(
            INSTANCING, '.vertexAttribDivisorANGLE(',
            i, ',',
            BINDING, '.divisor);')
        }
      }
      refresh(
        env.shared.vao, '.currentVAO=null;',
        env.shared.vao, '.setVAO(', env.shared.vao, '.targetVAO);')

      Object.keys(GL_FLAGS).forEach(function (flag) {
        var cap = GL_FLAGS[flag]
        var NEXT = common.def(NEXT_STATE, '.', flag)
        var block = env.block()
        block('if(', NEXT, '){',
          GL, '.enable(', cap, ')}else{',
          GL, '.disable(', cap, ')}',
          CURRENT_STATE, '.', flag, '=', NEXT, ';')
        refresh(block)
        poll(
          'if(', NEXT, '!==', CURRENT_STATE, '.', flag, '){',
          block,
          '}')
      })

      Object.keys(GL_VARIABLES).forEach(function (name) {
        var func = GL_VARIABLES[name]
        var init = currentState[name]
        var NEXT, CURRENT
        var block = env.block()
        block(GL, '.', func, '(')
        if (isArrayLike(init)) {
          var n = init.length
          NEXT = env.global.def(NEXT_STATE, '.', name)
          CURRENT = env.global.def(CURRENT_STATE, '.', name)
          block(
            loop(n, function (i) {
              return NEXT + '[' + i + ']'
            }), ');',
            loop(n, function (i) {
              return CURRENT + '[' + i + ']=' + NEXT + '[' + i + '];'
            }).join(''))
          poll(
            'if(', loop(n, function (i) {
              return NEXT + '[' + i + ']!==' + CURRENT + '[' + i + ']'
            }).join('||'), '){',
            block,
            '}')
        } else {
          NEXT = common.def(NEXT_STATE, '.', name)
          CURRENT = common.def(CURRENT_STATE, '.', name)
          block(
            NEXT, ');',
            CURRENT_STATE, '.', name, '=', NEXT, ';')
          poll(
            'if(', NEXT, '!==', CURRENT, '){',
            block,
            '}')
        }
        refresh(block)
      })

      return env.compile()
    })(),
    compile: compileCommand
  }
}