Roll webgl conformance tests to r17874: part 2, adding r17874

third_party/webgl/sdk/tests/conformance/resources/webgl-test-utils.js

+/*
+** Copyright (c) 2012 The Khronos Group Inc.
+**
+** Permission is hereby granted, free of charge, to any person obtaining a
+** copy of this software and/or associated documentation files (the
+** "Materials"), to deal in the Materials without restriction, including
+** without limitation the rights to use, copy, modify, merge, publish,
+** distribute, sublicense, and/or sell copies of the Materials, and to
+** permit persons to whom the Materials are furnished to do so, subject to
+** the following conditions:
+**
+** The above copyright notice and this permission notice shall be included
+** in all copies or substantial portions of the Materials.
+**
+** THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+** IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+** CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+** MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.
+*/
+
+WebGLTestUtils = (function() {
+
+/**
+ * Wrapped logging function.
+ * @param {string} msg The message to log.
+ */
+var log = function(msg) {
+  if (window.console && window.console.log) {
+    window.console.log(msg);
+  }
+};
+
+/**
+ * Wrapped logging function.
+ * @param {string} msg The message to log.
+ */
+var error = function(msg) {
+  if (window.console) {
+    if (window.console.error) {
+      window.console.error(msg);
+    }
+    else if (window.console.log) {
+      window.console.log(msg);
+    }
+  }
+};
+
+/**
+ * Turn off all logging.
+ */
+var loggingOff = function() {
+  log = function() {};
+  error = function() {};
+};
+
+/**
+ * Converts a WebGL enum to a string
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {number} value The enum value.
+ * @return {string} The enum as a string.
+ */
+var glEnumToString = function(gl, value) {
+  for (var p in gl) {
+    if (gl[p] == value) {
+      return p;
+    }
+  }
+  return "0x" + value.toString(16);
+};
+
+var lastError = "";
+
+/**
+ * Returns the last compiler/linker error.
+ * @return {string} The last compiler/linker error.
+ */
+var getLastError = function() {
+  return lastError;
+};
+
+/**
+ * Whether a haystack ends with a needle.
+ * @param {string} haystack String to search
+ * @param {string} needle String to search for.
+ * @param {boolean} True if haystack ends with needle.
+ */
+var endsWith = function(haystack, needle) {
+  return haystack.substr(haystack.length - needle.length) === needle;
+};
+
+/**
+ * Whether a haystack starts with a needle.
+ * @param {string} haystack String to search
+ * @param {string} needle String to search for.
+ * @param {boolean} True if haystack starts with needle.
+ */
+var startsWith = function(haystack, needle) {
+  return haystack.substr(0, needle.length) === needle;
+};
+
+/**
+ * A vertex shader for a single texture.
+ * @type {string}
+ */
+var simpleTextureVertexShader = [
+  'attribute vec4 vPosition;',
+  'attribute vec2 texCoord0;',
+  'varying vec2 texCoord;',
+  'void main() {',
+  '    gl_Position = vPosition;',
+  '    texCoord = texCoord0;',
+  '}'].join('\n');
+
+/**
+ * A fragment shader for a single texture.
+ * @type {string}
+ */
+var simpleTextureFragmentShader = [
+  'precision mediump float;',
+  'uniform sampler2D tex;',
+  'varying vec2 texCoord;',
+  'void main() {',
+  '    gl_FragData[0] = texture2D(tex, texCoord);',
+  '}'].join('\n');
+
+/**
+ * A vertex shader for a single texture.
+ * @type {string}
+ */
+var noTexCoordTextureVertexShader = [
+  'attribute vec4 vPosition;',
+  'varying vec2 texCoord;',
+  'void main() {',
+  '    gl_Position = vPosition;',
+  '    texCoord = vPosition.xy * 0.5 + 0.5;',
+  '}'].join('\n');
+
+/**
+ * A vertex shader for a single texture.
+ * @type {string}
+ */
+var simpleColorVertexShader = [
+  'attribute vec4 vPosition;',
+  'void main() {',
+  '    gl_Position = vPosition;',
+  '}'].join('\n');
+
+/**
+ * A fragment shader for a color.
+ * @type {string}
+ */
+var simpleColorFragmentShader = [
+  'precision mediump float;',
+  'uniform vec4 u_color;',
+  'void main() {',
+  '    gl_FragData[0] = u_color;',
+  '}'].join('\n');
+
+/**
+ * Creates a simple texture vertex shader.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @return {!WebGLShader}
+ */
+var setupSimpleTextureVertexShader = function(gl) {
+    return loadShader(gl, simpleTextureVertexShader, gl.VERTEX_SHADER);
+};
+
+/**
+ * Creates a simple texture fragment shader.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @return {!WebGLShader}
+ */
+var setupSimpleTextureFragmentShader = function(gl) {
+    return loadShader(
+        gl, simpleTextureFragmentShader, gl.FRAGMENT_SHADER);
+};
+
+/**
+ * Creates a texture vertex shader that doesn't need texcoords.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @return {!WebGLShader}
+ */
+var setupNoTexCoordTextureVertexShader = function(gl) {
+    return loadShader(gl, noTexCoordTextureVertexShader, gl.VERTEX_SHADER);
+};
+
+/**
+ * Creates a program, attaches shaders, binds attrib locations, links the
+ * program and calls useProgram.
+ * @param {!Array.<!WebGLShader|string>} shaders The shaders to
+ *        attach, or the source, or the id of a script to get
+ *        the source from.
+ * @param {!Array.<string>} opt_attribs The attribs names.
+ * @param {!Array.<number>} opt_locations The locations for the attribs.
+ */
+var setupProgram = function(gl, shaders, opt_attribs, opt_locations) {
+  var realShaders = [];
+  var program = gl.createProgram();
+  for (var ii = 0; ii < shaders.length; ++ii) {
+    var shader = shaders[ii];
+    if (typeof shader == 'string') {
+      var element = document.getElementById(shader);
+      if (element) {
+        shader = loadShaderFromScript(gl, shader);
+      } else {
+        shader = loadShader(gl, shader, ii ? gl.FRAGMENT_SHADER : gl.VERTEX_SHADER);
+      }
+    }
+    gl.attachShader(program, shader);
+  }
+  if (opt_attribs) {
+    for (var ii = 0; ii < opt_attribs.length; ++ii) {
+      gl.bindAttribLocation(
+          program,
+          opt_locations ? opt_locations[ii] : ii,
+          opt_attribs[ii]);
+    }
+  }
+  gl.linkProgram(program);
+
+  // Check the link status
+  var linked = gl.getProgramParameter(program, gl.LINK_STATUS);
+  if (!linked) {
+      // something went wrong with the link
+      lastError = gl.getProgramInfoLog (program);
+      error("Error in program linking:" + lastError);
+
+      gl.deleteProgram(program);
+      return null;
+  }
+
+  gl.useProgram(program);
+  return program;
+};
+
+/**
+ * Creates a simple texture program.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {number} opt_positionLocation The attrib location for position.
+ * @param {number} opt_texcoordLocation The attrib location for texture coords.
+ * @return {WebGLProgram}
+ */
+var setupSimpleTextureProgram = function(
+    gl, opt_positionLocation, opt_texcoordLocation) {
+  opt_positionLocation = opt_positionLocation || 0;
+  opt_texcoordLocation = opt_texcoordLocation || 1;
+  var vs = setupSimpleTextureVertexShader(gl);
+  var fs = setupSimpleTextureFragmentShader(gl);
+  if (!vs || !fs) {
+    return null;
+  }
+  var program = setupProgram(
+      gl,
+      [vs, fs],
+      ['vPosition', 'texCoord0'],
+      [opt_positionLocation, opt_texcoordLocation]);
+  if (!program) {
+    gl.deleteShader(fs);
+    gl.deleteShader(vs);
+  }
+  gl.useProgram(program);
+  return program;
+};
+
+/**
+ * Creates a simple texture program.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @return {WebGLProgram}
+ */
+var setupNoTexCoordTextureProgram = function(gl) {
+  var vs = setupNoTexCoordTextureVertexShader(gl);
+  var fs = setupSimpleTextureFragmentShader(gl);
+  if (!vs || !fs) {
+    return null;
+  }
+  var program = setupProgram(
+      gl,
+      [vs, fs],
+      ['vPosition'],
+      [0]);
+  if (!program) {
+    gl.deleteShader(fs);
+    gl.deleteShader(vs);
+  }
+  gl.useProgram(program);
+  return program;
+};
+
+/**
+ * Creates a simple texture program.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {number} opt_positionLocation The attrib location for position.
+ * @param {number} opt_texcoordLocation The attrib location for texture coords.
+ * @return {WebGLProgram}
+ */
+var setupSimpleTextureProgram = function(
+    gl, opt_positionLocation, opt_texcoordLocation) {
+  opt_positionLocation = opt_positionLocation || 0;
+  opt_texcoordLocation = opt_texcoordLocation || 1;
+  var vs = setupSimpleTextureVertexShader(gl);
+  var fs = setupSimpleTextureFragmentShader(gl);
+  if (!vs || !fs) {
+    return null;
+  }
+  var program = setupProgram(
+      gl,
+      [vs, fs],
+      ['vPosition', 'texCoord0'],
+      [opt_positionLocation, opt_texcoordLocation]);
+  if (!program) {
+    gl.deleteShader(fs);
+    gl.deleteShader(vs);
+  }
+  gl.useProgram(program);
+  return program;
+};
+
+/**
+ * Creates buffers for a textured unit quad and attaches them to vertex attribs.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {number} opt_positionLocation The attrib location for position.
+ * @param {number} opt_texcoordLocation The attrib location for texture coords.
+ * @return {!Array.<WebGLBuffer>} The buffer objects that were
+ *      created.
+ */
+var setupUnitQuad = function(gl, opt_positionLocation, opt_texcoordLocation) {
+  return setupUnitQuadWithTexCoords(gl, [ 0.0, 0.0 ], [ 1.0, 1.0 ],
+                                    opt_positionLocation, opt_texcoordLocation);
+};
+
+/**
+ * Creates buffers for a textured unit quad with specified lower left
+ * and upper right texture coordinates, and attaches them to vertex
+ * attribs.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {!Array.<number>} lowerLeftTexCoords The texture coordinates for the lower left corner.
+ * @param {!Array.<number>} upperRightTexCoords The texture coordinates for the upper right corner.
+ * @param {number} opt_positionLocation The attrib location for position.
+ * @param {number} opt_texcoordLocation The attrib location for texture coords.
+ * @return {!Array.<WebGLBuffer>} The buffer objects that were
+ *      created.
+ */
+var setupUnitQuadWithTexCoords = function(
+    gl, lowerLeftTexCoords, upperRightTexCoords,
+    opt_positionLocation, opt_texcoordLocation) {
+  opt_positionLocation = opt_positionLocation || 0;
+  opt_texcoordLocation = opt_texcoordLocation || 1;
+  var objects = [];
+
+  var vertexObject = gl.createBuffer();
+  gl.bindBuffer(gl.ARRAY_BUFFER, vertexObject);
+  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
+       1.0,  1.0, 0.0,
+      -1.0,  1.0, 0.0,
+      -1.0, -1.0, 0.0,
+       1.0,  1.0, 0.0,
+      -1.0, -1.0, 0.0,
+       1.0, -1.0, 0.0]), gl.STATIC_DRAW);
+  gl.enableVertexAttribArray(opt_positionLocation);
+  gl.vertexAttribPointer(opt_positionLocation, 3, gl.FLOAT, false, 0, 0);
+  objects.push(vertexObject);
+
+  var llx = lowerLeftTexCoords[0];
+  var lly = lowerLeftTexCoords[1];
+  var urx = upperRightTexCoords[0];
+  var ury = upperRightTexCoords[1];
+
+  var vertexObject = gl.createBuffer();
+  gl.bindBuffer(gl.ARRAY_BUFFER, vertexObject);
+  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
+      urx, ury,
+      llx, ury,
+      llx, lly,
+      urx, ury,
+      llx, lly,
+      urx, lly]), gl.STATIC_DRAW);
+  gl.enableVertexAttribArray(opt_texcoordLocation);
+  gl.vertexAttribPointer(opt_texcoordLocation, 2, gl.FLOAT, false, 0, 0);
+  objects.push(vertexObject);
+  return objects;
+};
+
+/**
+ * Creates a program and buffers for rendering a textured quad.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {number} opt_positionLocation The attrib location for position.
+ * @param {number} opt_texcoordLocation The attrib location for texture coords.
+ * @return {!WebGLProgram}
+ */
+var setupTexturedQuad = function(
+    gl, opt_positionLocation, opt_texcoordLocation) {
+  var program = setupSimpleTextureProgram(
+      gl, opt_positionLocation, opt_texcoordLocation);
+  setupUnitQuad(gl, opt_positionLocation, opt_texcoordLocation);
+  return program;
+};
+
+/**
+ * Creates a program and buffers for rendering a color quad.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {number} opt_positionLocation The attrib location for position.
+ * @return {!WebGLProgram}
+ */
+var setupColorQuad = function(gl, opt_positionLocation) {
+  opt_positionLocation = opt_positionLocation || 0;
+  var program = wtu.setupProgram(
+      gl,
+      [simpleColorVertexShader, simpleColorFragmentShader],
+      ['vPosition'],
+      [opt_positionLocation]);
+  setupUnitQuad(gl, opt_positionLocation);
+  return program;
+};
+
+/**
+ * Creates a program and buffers for rendering a textured quad with
+ * specified lower left and upper right texture coordinates.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {!Array.<number>} lowerLeftTexCoords The texture coordinates for the lower left corner.
+ * @param {!Array.<number>} upperRightTexCoords The texture coordinates for the upper right corner.
+ * @param {number} opt_positionLocation The attrib location for position.
+ * @param {number} opt_texcoordLocation The attrib location for texture coords.
+ * @return {!WebGLProgram}
+ */
+var setupTexturedQuadWithTexCoords = function(
+    gl, lowerLeftTexCoords, upperRightTexCoords,
+    opt_positionLocation, opt_texcoordLocation) {
+  var program = setupSimpleTextureProgram(
+      gl, opt_positionLocation, opt_texcoordLocation);
+  setupUnitQuadWithTexCoords(gl, lowerLeftTexCoords, upperRightTexCoords,
+                             opt_positionLocation, opt_texcoordLocation);
+  return program;
+};
+
+/**
+ * Creates a unit quad with only positions of a given resolution.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {number} gridRes The resolution of the mesh grid,
+ *     expressed in the number of quads across and down.
+ * @param {number} opt_positionLocation The attrib location for position.
+ */
+var setupQuad = function (
+    gl, gridRes, opt_positionLocation, opt_flipOddTriangles) {
+  setupQuadWithOptions(gl,
+    { gridRes: gridRes,
+      positionLocation: opt_positionLocation,
+      flipOddTriangles: opt_flipOddTriangles
+    });
+};
+
+/**
+ * Creates a quad with various options.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ *
+ * Options:
+ *   gridRes: number of quads across and down grid.
+ *   positionLocation: attrib location for position
+ *   flipOddTriangles: reverse order of vertices of every other
+ *       triangle
+ *   positionOffset: offset added to each vertex
+ *   positionMult: multipier for each vertex
+ *   colorLocation: attrib location for vertex colors. If
+ *      undefined no vertex colors will be created.
+ */
+var setupQuadWithOptions = function (gl, options) {
+  var positionLocation = options.positionLocation || 0;
+  var objects = [];
+
+  var gridRes = options.gridRes || 1;
+  var positionOffset = options.positionOffset || 0;
+  var positionMult = options.positionMult || 1;
+  var vertsAcross = gridRes + 1;
+  var numVerts = vertsAcross * vertsAcross;
+  var positions = new Float32Array(numVerts * 3);
+  var indices = new Uint16Array(6 * gridRes * gridRes);
+  var poffset = 0;
+
+  for (var yy = 0; yy <= gridRes; ++yy) {
+    for (var xx = 0; xx <= gridRes; ++xx) {
+      positions[poffset + 0] = (-1 + 2 * xx / gridRes) * positionMult + positionOffset;
+      positions[poffset + 1] = (-1 + 2 * yy / gridRes) * positionMult + positionOffset;
+      positions[poffset + 2] = 0;
+
+      poffset += 3;
+    }
+  }
+
+  var buf = gl.createBuffer();
+  gl.bindBuffer(gl.ARRAY_BUFFER, buf);
+  gl.bufferData(gl.ARRAY_BUFFER, positions, gl.STATIC_DRAW);
+  gl.enableVertexAttribArray(positionLocation);
+  gl.vertexAttribPointer(positionLocation, 3, gl.FLOAT, false, 0, 0);
+  objects.push(buf);
+
+  if (options.colorLocation !== undefined) {
+    var colors = new Float32Array(numVerts * 4);
+    for (var yy = 0; yy <= gridRes; ++yy) {
+      for (var xx = 0; xx <= gridRes; ++xx) {
+        if (options.color !== undefined) {
+          colors[poffset + 0] = options.color[0];
+          colors[poffset + 1] = options.color[1];
+          colors[poffset + 2] = options.color[2];
+          colors[poffset + 3] = options.color[3];
+        } else {
+          colors[poffset + 0] = xx / gridRes;
+          colors[poffset + 1] = yy / gridRes;
+          colors[poffset + 2] = (xx / gridRes) * (yy / gridRes);
+          colors[poffset + 3] = (yy % 2) * 0.5 + 0.5;
+        }
+        poffset += 4;
+      }
+    }
+
+    var buf = gl.createBuffer();
+    gl.bindBuffer(gl.ARRAY_BUFFER, buf);
+    gl.bufferData(gl.ARRAY_BUFFER, colors, gl.STATIC_DRAW);
+    gl.enableVertexAttribArray(options.colorLocation);
+    gl.vertexAttribPointer(options.colorLocation, 4, gl.FLOAT, false, 0, 0);
+    objects.push(buf);
+  }
+
+  var tbase = 0;
+  for (var yy = 0; yy < gridRes; ++yy) {
+    var index = yy * vertsAcross;
+    for (var xx = 0; xx < gridRes; ++xx) {
+      indices[tbase + 0] = index + 0;
+      indices[tbase + 1] = index + 1;
+      indices[tbase + 2] = index + vertsAcross;
+      indices[tbase + 3] = index + vertsAcross;
+      indices[tbase + 4] = index + 1;
+      indices[tbase + 5] = index + vertsAcross + 1;
+
+      if (options.flipOddTriangles) {
+        indices[tbase + 4] = index + vertsAcross + 1;
+        indices[tbase + 5] = index + 1;
+      }
+
+      index += 1;
+      tbase += 6;
+    }
+  }
+
+  var buf = gl.createBuffer();
+  gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, buf);
+  gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, indices, gl.STATIC_DRAW);
+  objects.push(buf);
+
+  return objects;
+};
+
+/**
+ * Fills the given texture with a solid color
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {!WebGLTexture} tex The texture to fill.
+ * @param {number} width The width of the texture to create.
+ * @param {number} height The height of the texture to create.
+ * @param {!Array.<number>} color The color to fill with. A 4 element array
+ *        where each element is in the range 0 to 255.
+ * @param {number} opt_level The level of the texture to fill. Default = 0.
+ */
+var fillTexture = function(gl, tex, width, height, color, opt_level) {
+  opt_level = opt_level || 0;
+  var numPixels = width * height;
+  var size = numPixels * 4;
+  var buf = new Uint8Array(size);
+  for (var ii = 0; ii < numPixels; ++ii) {
+    var off = ii * 4;
+    buf[off + 0] = color[0];
+    buf[off + 1] = color[1];
+    buf[off + 2] = color[2];
+    buf[off + 3] = color[3];
+  }
+  gl.bindTexture(gl.TEXTURE_2D, tex);
+  gl.texImage2D(
+      gl.TEXTURE_2D, opt_level, gl.RGBA, width, height, 0,
+      gl.RGBA, gl.UNSIGNED_BYTE, buf);
+  };
+
+/**
+ * Creates a textures and fills it with a solid color
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {number} width The width of the texture to create.
+ * @param {number} height The height of the texture to create.
+ * @param {!Array.<number>} color The color to fill with. A 4 element array
+ *        where each element is in the range 0 to 255.
+ * @return {!WebGLTexture}
+ */
+var createColoredTexture = function(gl, width, height, color) {
+  var tex = gl.createTexture();
+  fillTexture(gl, tex, width, height, color);
+  return tex;
+};
+
+/**
+ * Draws a previously setup quad.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {!Array.<number>} opt_color The color to fill clear with before
+ *        drawing. A 4 element array where each element is in the range 0 to
+ *        255. Default [255, 255, 255, 255]
+ */
+var drawQuad = function(gl, opt_color) {
+  opt_color = opt_color || [255, 255, 255, 255];
+  gl.clearColor(
+      opt_color[0] / 255,
+      opt_color[1] / 255,
+      opt_color[2] / 255,
+      opt_color[3] / 255);
+  gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
+  gl.drawArrays(gl.TRIANGLES, 0, 6);
+};
+
+/**
+ * Draws a previously setup quad.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {number} gridRes Resolution of grid.
+ * @param {!Array.<number>} opt_color The color to fill clear with before
+ *        drawing. A 4 element array where each element is in the range 0 to
+ *        255. Default [255, 255, 255, 255]
+ */
+var drawIndexedQuad = function(gl, gridRes, opt_color) {
+  opt_color = opt_color || [255, 255, 255, 255];
+  gl.clearColor(
+      opt_color[0] / 255,
+      opt_color[1] / 255,
+      opt_color[2] / 255,
+      opt_color[3] / 255);
+  gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
+  gl.drawElements(gl.TRIANGLES, gridRes * 6, gl.UNSIGNED_SHORT, 0);
+};
+
+/**
+ * Checks that a portion of a canvas is 1 color.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {number} x left corner of region to check.
+ * @param {number} y bottom corner of region to check.
+ * @param {number} width width of region to check.
+ * @param {number} height width of region to check.
+ * @param {!Array.<number>} color The color to fill clear with before drawing. A
+ *        4 element array where each element is in the range 0 to 255.
+ * @param {string} msg Message to associate with success. Eg ("should be red").
+ * @param {number} errorRange Optional. Acceptable error in
+ *        color checking. 0 by default.
+ */
+var checkCanvasRect = function(gl, x, y, width, height, color, msg, errorRange) {
+  errorRange = errorRange || 0;
+  if (!errorRange.length) {
+    errorRange = [errorRange, errorRange, errorRange, errorRange]
+  }
+  var buf = new Uint8Array(width * height * 4);
+  gl.readPixels(x, y, width, height, gl.RGBA, gl.UNSIGNED_BYTE, buf);
+  for (var i = 0; i < width * height; ++i) {
+    var offset = i * 4;
+    for (var j = 0; j < color.length; ++j) {
+      if (Math.abs(buf[offset + j] - color[j]) > errorRange[j]) {
+        testFailed(msg);
+        var was = buf[offset + 0].toString();
+        for (j = 1; j < color.length; ++j) {
+          was += "," + buf[offset + j];
+        }
+        debug('at (' + (i % width) + ', ' + Math.floor(i / width) +
+              ') expected: ' + color + ' was ' + was);
+        return;
+      }
+    }
+  }
+  testPassed(msg);
+};
+
+/**
+ * Checks that an entire canvas is 1 color.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {!Array.<number>} color The color to fill clear with before drawing. A
+ *        4 element array where each element is in the range 0 to 255.
+ * @param {string} msg Message to associate with success. Eg ("should be red").
+ * @param {number} errorRange Optional. Acceptable error in
+ *        color checking. 0 by default.
+ */
+var checkCanvas = function(gl, color, msg, errorRange) {
+  checkCanvasRect(gl, 0, 0, gl.canvas.width, gl.canvas.height, color, msg, errorRange);
+};
+
+/**
+ * Loads a texture, calls callback when finished.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {string} url URL of image to load
+ * @param {function(!Image): void} callback Function that gets called after
+ *        image has loaded
+ * @return {!WebGLTexture} The created texture.
+ */
+var loadTexture = function(gl, url, callback) {
+    var texture = gl.createTexture();
+    gl.bindTexture(gl.TEXTURE_2D, texture);
+    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
+    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
+    var image = new Image();
+    image.onload = function() {
+        gl.bindTexture(gl.TEXTURE_2D, texture);
+        gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);
+        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, image);
+        callback(image);
+    };
+    image.src = url;
+    return texture;
+};
+
+/**
+ * Creates a webgl context.
+ * @param {!Canvas|string} opt_canvas The canvas tag to get
+ *     context from. If one is not passed in one will be
+ *     created. If it's a string it's assumed to be the id of a
+ *     canvas.
+ * @return {!WebGLContext} The created context.
+ */
+var create3DContext = function(opt_canvas, opt_attributes) {
+  opt_canvas = opt_canvas || document.createElement("canvas");
+  if (typeof opt_canvas == 'string') {
+    opt_canvas = document.getElementById(opt_canvas);
+  }
+  var context = null;
+  var names = ["webgl", "experimental-webgl"];
+  for (var i = 0; i < names.length; ++i) {
+    try {
+      context = opt_canvas.getContext(names[i], opt_attributes);
+    } catch (e) {
+    }
+    if (context) {
+      break;
+    }
+  }
+  if (!context) {
+    testFailed("Unable to fetch WebGL rendering context for Canvas");
+  }
+  return context;
+}
+
+/**
+ * Gets a GLError value as a string.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {number} err The webgl error as retrieved from gl.getError().
+ * @return {string} the error as a string.
+ */
+var getGLErrorAsString = function(gl, err) {
+  if (err === gl.NO_ERROR) {
+    return "NO_ERROR";
+  }
+  for (var name in gl) {
+    if (gl[name] === err) {
+      return name;
+    }
+  }
+  return err.toString();
+};
+
+/**
+ * Wraps a WebGL function with a function that throws an exception if there is
+ * an error.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {string} fname Name of function to wrap.
+ * @return {function} The wrapped function.
+ */
+var createGLErrorWrapper = function(context, fname) {
+  return function() {
+    var rv = context[fname].apply(context, arguments);
+    var err = context.getError();
+    if (err != context.NO_ERROR)
+      throw "GL error " + getGLErrorAsString(context, err) + " in " + fname;
+    return rv;
+  };
+};
+
+/**
+ * Creates a WebGL context where all functions are wrapped to throw an exception
+ * if there is an error.
+ * @param {!Canvas} canvas The HTML canvas to get a context from.
+ * @return {!Object} The wrapped context.
+ */
+function create3DContextWithWrapperThatThrowsOnGLError(canvas) {
+  var context = create3DContext(canvas);
+  var wrap = {};
+  for (var i in context) {
+    try {
+      if (typeof context[i] == 'function') {
+        wrap[i] = createGLErrorWrapper(context, i);
+      } else {
+        wrap[i] = context[i];
+      }
+    } catch (e) {
+      error("createContextWrapperThatThrowsOnGLError: Error accessing " + i);
+    }
+  }
+  wrap.getError = function() {
+      return context.getError();
+  };
+  return wrap;
+};
+
+/**
+ * Tests that an evaluated expression generates a specific GL error.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {number} glError The expected gl error.
+ * @param {string} evalSTr The string to evaluate.
+ */
+var shouldGenerateGLError = function(gl, glError, evalStr) {
+  var exception;
+  try {
+    eval(evalStr);
+  } catch (e) {
+    exception = e;
+  }
+  if (exception) {
+    testFailed(evalStr + " threw exception " + exception);
+  } else {
+    var err = gl.getError();
+    if (err != glError) {
+      testFailed(evalStr + " expected: " + getGLErrorAsString(gl, glError) + ". Was " + getGLErrorAsString(gl, err) + ".");
+    } else {
+      testPassed(evalStr + " was expected value: " + getGLErrorAsString(gl, glError) + ".");
+    }
+  }
+};
+
+/**
+ * Tests that the first error GL returns is the specified error.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {number} glError The expected gl error.
+ * @param {string} opt_msg
+ */
+var glErrorShouldBe = function(gl, glError, opt_msg) {
+  opt_msg = opt_msg || "";
+  var err = gl.getError();
+  if (err != glError) {
+    testFailed("getError expected: " + getGLErrorAsString(gl, glError) +
+               ". Was " + getGLErrorAsString(gl, err) + " : " + opt_msg);
+  } else {
+    testPassed("getError was expected value: " +
+                getGLErrorAsString(gl, glError) + " : " + opt_msg);
+  }
+};
+
+/**
+ * Links a WebGL program, throws if there are errors.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {!WebGLProgram} program The WebGLProgram to link.
+ * @param {function(string): void) opt_errorCallback callback for errors. 
+ */
+var linkProgram = function(gl, program, opt_errorCallback) {
+  errFn = opt_errorCallback || testFailed;
+  // Link the program
+  gl.linkProgram(program);
+
+  // Check the link status
+  var linked = gl.getProgramParameter(program, gl.LINK_STATUS);
+  if (!linked) {
+    // something went wrong with the link
+    var error = gl.getProgramInfoLog (program);
+
+    errFn("Error in program linking:" + error);
+
+    gl.deleteProgram(program);
+  }
+};
+
+/**
+ * Loads text from an external file. This function is synchronous.
+ * @param {string} url The url of the external file.
+ * @param {!function(bool, string): void} callback that is sent a bool for
+ *     success and the string.
+ */
+var loadTextFileAsync = function(url, callback) {
+  log ("loading: " + url);
+  var error = 'loadTextFileSynchronous failed to load url "' + url + '"';
+  var request;
+  if (window.XMLHttpRequest) {
+    request = new XMLHttpRequest();
+    if (request.overrideMimeType) {
+      request.overrideMimeType('text/plain');
+    }
+  } else {
+    throw 'XMLHttpRequest is disabled';
+  }
+  try {
+    request.open('GET', url, true);
+    request.onreadystatechange = function() {
+      if (request.readyState == 4) {
+        var text = '';
+        // HTTP reports success with a 200 status. The file protocol reports
+        // success with zero. HTTP does not use zero as a status code (they
+        // start at 100).
+        // https://developer.mozilla.org/En/Using_XMLHttpRequest
+        var success = request.status == 200 || request.status == 0;
+        if (success) {
+          text = request.responseText;
+        }
+        log("loaded: " + url);
+        callback(success, text);
+      }
+    };
+    request.send(null);
+  } catch (e) {
+    log("failed to load: " + url);
+    callback(false, '');
+  }
+};
+
+/**
+ * Recursively loads a file as a list. Each line is parsed for a relative
+ * path. If the file ends in .txt the contents of that file is inserted in
+ * the list.
+ *
+ * @param {string} url The url of the external file.
+ * @param {!function(bool, Array<string>): void} callback that is sent a bool
+ *     for success and the array of strings.
+ */
+var getFileListAsync = function(url, callback) {
+  var files = [];
+
+  var getFileListImpl = function(url, callback) {
+    var files = [];
+    if (url.substr(url.length - 4) == '.txt') {
+      loadTextFileAsync(url, function() {
+        return function(success, text) {
+          if (!success) {
+            callback(false, '');
+            return;
+          }
+          var lines = text.split('\n');
+          var prefix = '';
+          var lastSlash = url.lastIndexOf('/');
+          if (lastSlash >= 0) {
+            prefix = url.substr(0, lastSlash + 1);
+          }
+          var fail = false;
+          var count = 1;
+          var index = 0;
+          for (var ii = 0; ii < lines.length; ++ii) {
+            var str = lines[ii].replace(/^\s\s*/, '').replace(/\s\s*$/, '');
+            if (str.length > 4 &&
+                str[0] != '#' &&
+                str[0] != ";" &&
+                str.substr(0, 2) != "//") {
+              var names = str.split(/ +/);
+              new_url = prefix + str;
+              if (names.length == 1) {
+                new_url = prefix + str;
+                ++count;
+                getFileListImpl(new_url, function(index) {
+                  return function(success, new_files) {
+                    log("got files: " + new_files.length);
+                    if (success) {
+                      files[index] = new_files;
+                    }
+                    finish(success);
+                  };
+                }(index++));
+              } else {
+                var s = "";
+                var p = "";
+                for (var jj = 0; jj < names.length; ++jj) {
+                  s += p + prefix + names[jj];
+                  p = " ";
+                }
+                files[index++] = s;
+              }
+            }
+          }
+          finish(true);
+
+          function finish(success) {
+            if (!success) {
+              fail = true;
+            }
+            --count;
+            log("count: " + count);
+            if (!count) {
+              callback(!fail, files);
+            }
+          }
+        }
+      }());
+
+    } else {
+      files.push(url);
+      callback(true, files);
+    }
+  };
+
+  getFileListImpl(url, function(success, files) {
+    // flatten
+    var flat = [];
+    flatten(files);
+    function flatten(files) {
+      for (var ii = 0; ii < files.length; ++ii) {
+        var value = files[ii];
+        if (typeof(value) == "string") {
+          flat.push(value);
+        } else {
+          flatten(value);
+        }
+      }
+    }
+    callback(success, flat);
+  });
+};
+
+/**
+ * Gets a file from a file/URL
+ * @param {string} file the URL of the file to get.
+ * @return {string} The contents of the file.
+ */
+var readFile = function(file) {
+  var xhr = new XMLHttpRequest();
+  xhr.open("GET", file, false);
+  xhr.send();
+  return xhr.responseText.replace(/\r/g, "");
+};
+
+var readFileList = function(url) {
+  var files = [];
+  if (url.substr(url.length - 4) == '.txt') {
+    var lines = readFile(url).split('\n');
+    var prefix = '';
+    var lastSlash = url.lastIndexOf('/');
+    if (lastSlash >= 0) {
+      prefix = url.substr(0, lastSlash + 1);
+    }
+    for (var ii = 0; ii < lines.length; ++ii) {
+      var str = lines[ii].replace(/^\s\s*/, '').replace(/\s\s*$/, '');
+      if (str.length > 4 &&
+          str[0] != '#' &&
+          str[0] != ";" &&
+          str.substr(0, 2) != "//") {
+        var names = str.split(/ +/);
+        if (names.length == 1) {
+          new_url = prefix + str;
+          files = files.concat(readFileList(new_url));
+        } else {
+          var s = "";
+          var p = "";
+          for (var jj = 0; jj < names.length; ++jj) {
+            s += p + prefix + names[jj];
+            p = " ";
+          }
+          files.push(s);
+        }
+      }
+    }
+  } else {
+    files.push(url);
+  }
+  return files;
+};
+
+/**
+ * Loads a shader.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {string} shaderSource The shader source.
+ * @param {number} shaderType The type of shader. 
+ * @param {function(string): void) opt_errorCallback callback for errors. 
+ * @return {!WebGLShader} The created shader.
+ */
+var loadShader = function(gl, shaderSource, shaderType, opt_errorCallback) {
+  var errFn = opt_errorCallback || error;
+  // Create the shader object
+  var shader = gl.createShader(shaderType);
+  if (shader == null) {
+    errFn("*** Error: unable to create shader '"+shaderSource+"'");
+    return null;
+  }
+
+  // Load the shader source
+  gl.shaderSource(shader, shaderSource);
+  var err = gl.getError();
+  if (err != gl.NO_ERROR) {
+    errFn("*** Error loading shader '" + shader + "':" + glEnumToString(gl, err));
+    return null;
+  }
+
+  // Compile the shader
+  gl.compileShader(shader);
+
+  // Check the compile status
+  var compiled = gl.getShaderParameter(shader, gl.COMPILE_STATUS);
+  if (!compiled) {
+    // Something went wrong during compilation; get the error
+    lastError = gl.getShaderInfoLog(shader);
+    errFn("*** Error compiling shader '" + shader + "':" + lastError);
+    gl.deleteShader(shader);
+    return null;
+  }
+
+  return shader;
+}
+
+/**
+ * Loads a shader from a URL.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {file} file The URL of the shader source.
+ * @param {number} type The type of shader.
+ * @param {function(string): void) opt_errorCallback callback for errors. 
+ * @return {!WebGLShader} The created shader.
+ */
+var loadShaderFromFile = function(gl, file, type, opt_errorCallback) {
+  var shaderSource = readFile(file);
+  return loadShader(gl, shaderSource, type, opt_errorCallback);
+};
+
+/**
+ * Gets the content of script.
+ */
+var getScript = function(scriptId) {
+  var shaderScript = document.getElementById(scriptId);
+  if (!shaderScript) {
+    throw("*** Error: unknown script element" + scriptId);
+  }
+  return shaderScript.text;
+};
+
+/**
+ * Loads a shader from a script tag.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {string} scriptId The id of the script tag.
+ * @param {number} opt_shaderType The type of shader. If not passed in it will
+ *     be derived from the type of the script tag.
+ * @param {function(string): void) opt_errorCallback callback for errors. 
+ * @return {!WebGLShader} The created shader.
+ */
+var loadShaderFromScript = function(
+    gl, scriptId, opt_shaderType, opt_errorCallback) {
+  var shaderSource = "";
+  var shaderType;
+  var shaderScript = document.getElementById(scriptId);
+  if (!shaderScript) {
+    throw("*** Error: unknown script element " + scriptId);
+  }
+  shaderSource = shaderScript.text;
+
+  if (!opt_shaderType) {
+    if (shaderScript.type == "x-shader/x-vertex") {
+      shaderType = gl.VERTEX_SHADER;
+    } else if (shaderScript.type == "x-shader/x-fragment") {
+      shaderType = gl.FRAGMENT_SHADER;
+    } else if (shaderType != gl.VERTEX_SHADER && shaderType != gl.FRAGMENT_SHADER) {
+      throw("*** Error: unknown shader type");
+      return null;
+    }
+  }
+
+  return loadShader(
+      gl, shaderSource, opt_shaderType ? opt_shaderType : shaderType,
+      opt_errorCallback);
+};
+
+var loadStandardProgram = function(gl) {
+  var program = gl.createProgram();
+  gl.attachShader(program, loadStandardVertexShader(gl));
+  gl.attachShader(program, loadStandardFragmentShader(gl));
+  linkProgram(gl, program);
+  return program;
+};
+
+/**
+ * Loads shaders from files, creates a program, attaches the shaders and links.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {string} vertexShaderPath The URL of the vertex shader.
+ * @param {string} fragmentShaderPath The URL of the fragment shader.
+ * @param {function(string): void) opt_errorCallback callback for errors. 
+ * @return {!WebGLProgram} The created program.
+ */
+var loadProgramFromFile = function(
+    gl, vertexShaderPath, fragmentShaderPath, opt_errorCallback) {
+  var program = gl.createProgram();
+  var vs = loadShaderFromFile(
+      gl, vertexShaderPath, gl.VERTEX_SHADER, opt_errorCallback);
+  var fs = loadShaderFromFile(
+      gl, fragmentShaderPath, gl.FRAGMENT_SHADER, opt_errorCallback);
+  if (vs && fs) {
+    gl.attachShader(program, vs);
+    gl.attachShader(program, fs);
+    linkProgram(gl, program, opt_errorCallback);
+  }
+  if (vs) {
+    gl.deleteShader(vs);
+  }
+  if (fs) {
+    gl.deleteShader(fs);
+  }
+  return program;
+};
+
+/**
+ * Loads shaders from script tags, creates a program, attaches the shaders and
+ * links.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {string} vertexScriptId The id of the script tag that contains the
+ *        vertex shader.
+ * @param {string} fragmentScriptId The id of the script tag that contains the
+ *        fragment shader.
+ * @param {function(string): void) opt_errorCallback callback for errors. 
+ * @return {!WebGLProgram} The created program.
+ */
+var loadProgramFromScript = function loadProgramFromScript(
+    gl, vertexScriptId, fragmentScriptId, opt_errorCallback) {
+  var program = gl.createProgram();
+  gl.attachShader(
+      program,
+      loadShaderFromScript(
+          gl, vertexScriptId, gl.VERTEX_SHADER, opt_errorCallback));
+  gl.attachShader(
+      program,
+      loadShaderFromScript(
+          gl, fragmentScriptId,  gl.FRAGMENT_SHADER, opt_errorCallback));
+  linkProgram(gl, program, opt_errorCallback);
+  return program;
+};
+
+/**
+ * Loads shaders from source, creates a program, attaches the shaders and
+ * links.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {!WebGLShader} vertexShader The vertex shader.
+ * @param {!WebGLShader} fragmentShader The fragment shader.
+ * @param {function(string): void) opt_errorCallback callback for errors.
+ * @return {!WebGLProgram} The created program.
+ */
+var createProgram = function(gl, vertexShader, fragmentShader, opt_errorCallback) {
+  var program = gl.createProgram();
+  gl.attachShader(program, vertexShader);
+  gl.attachShader(program, fragmentShader);
+  linkProgram(gl, program, opt_errorCallback);
+  return program;
+};
+
+/**
+ * Loads shaders from source, creates a program, attaches the shaders and
+ * links.
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {string} vertexShader The vertex shader source.
+ * @param {string} fragmentShader The fragment shader source.
+ * @param {function(string): void) opt_errorCallback callback for errors. 
+ * @return {!WebGLProgram} The created program.
+ */
+var loadProgram = function(
+    gl, vertexShader, fragmentShader, opt_errorCallback) {
+  var program;
+  var vs = loadShader(
+      gl, vertexShader, gl.VERTEX_SHADER, opt_errorCallback);
+  var fs = loadShader(
+      gl, fragmentShader, gl.FRAGMENT_SHADER, opt_errorCallback);
+  if (vs && fs) {
+    program = createProgram(gl, vs, fs, opt_errorCallback)
+  }
+  if (vs) {
+    gl.deleteShader(vs);
+  }
+  if (fs) {
+    gl.deleteShader(fs);
+  }
+  return program;
+};
+
+/**
+ * Loads shaders from source, creates a program, attaches the shaders and
+ * links but expects error.
+ *
+ * GLSL 1.0.17 10.27 effectively says that compileShader can
+ * always succeed as long as linkProgram fails so we can't
+ * rely on compileShader failing. This function expects
+ * one of the shader to fail OR linking to fail.
+ *
+ * @param {!WebGLContext} gl The WebGLContext to use.
+ * @param {string} vertexShaderScriptId The vertex shader.
+ * @param {string} fragmentShaderScriptId The fragment shader.
+ * @return {WebGLProgram} The created program.
+ */
+var loadProgramFromScriptExpectError = function(
+    gl, vertexShaderScriptId, fragmentShaderScriptId) {
+  var vertexShader = loadShaderFromScript(gl, vertexShaderScriptId);
+  if (!vertexShader) {
+    return null;
+  }
+  var fragmentShader = loadShaderFromScript(gl, fragmentShaderScriptId);
+  if (!fragmentShader) {
+    return null;
+  }
+  var linkSuccess = true;
+  var program = gl.createProgram();
+  gl.attachShader(program, vertexShader);
+  gl.attachShader(program, fragmentShader);
+  linkSuccess = true;
+  linkProgram(gl, program, function() {
+      linkSuccess = false;
+    });
+  return linkSuccess ? program : null;
+};
+
+var basePath;
+var getBasePath = function() {
+  if (!basePath) {
+    var expectedBase = "webgl-test-utils.js";
+    var scripts = document.getElementsByTagName('script');
+    for (var script, i = 0; script = scripts[i]; i++) {
+      var src = script.src;
+      var l = src.length;
+      if (src.substr(l - expectedBase.length) == expectedBase) {
+        basePath = src.substr(0, l - expectedBase.length);
+      }
+    }
+  }
+  return basePath;
+};
+
+var loadStandardVertexShader = function(gl) {
+  return loadShaderFromFile(
+      gl, getBasePath() + "vertexShader.vert", gl.VERTEX_SHADER);
+};
+
+var loadStandardFragmentShader = function(gl) {
+  return loadShaderFromFile(
+      gl, getBasePath() + "fragmentShader.frag", gl.FRAGMENT_SHADER);
+};
+
+/**
+ * Loads an image asynchronously.
+ * @param {string} url URL of image to load.
+ * @param {!function(!Element): void} callback Function to call
+ *     with loaded image.
+ */
+var loadImageAsync = function(url, callback) {
+  var img = document.createElement('img');
+  img.onload = function() {
+    callback(img);
+  };
+  img.src = url;
+};
+
+/**
+ * Loads an array of images.
+ * @param {!Array.<string>} urls URLs of images to load.
+ * @param {!function(!{string, img}): void} callback. Callback
+ *     that gets passed map of urls to img tags.
+ */
+var loadImagesAsync = function(urls, callback) {
+  var count = 1;
+  var images = { };
+  function countDown() {
+    --count;
+    if (count == 0) {
+      callback(images);
+    }
+  }
+  function imageLoaded(url) {
+    return function(img) {
+      images[url] = img;
+      countDown();
+    }
+  }
+  for (var ii = 0; ii < urls.length; ++ii) {
+    ++count;
+    loadImageAsync(urls[ii], imageLoaded(urls[ii]));
+  }
+  countDown();
+};
+
+var getUrlArguments = function() {
+  var args = {};
+  try {
+    var s = window.location.href;
+    var q = s.indexOf("?");
+    var e = s.indexOf("#");
+    if (e < 0) {
+      e = s.length;
+    }
+    var query = s.substring(q + 1, e);
+    var pairs = query.split("&");
+    for (var ii = 0; ii < pairs.length; ++ii) {
+      var keyValue = pairs[ii].split("=");
+      var key = keyValue[0];
+      var value = decodeURIComponent(keyValue[1]);
+      args[key] = value;
+    }
+  } catch (e) {
+    throw "could not parse url";
+  }
+  return args;
+};
+
+var makeImage = function(canvas) {
+  var img = document.createElement('img');
+  img.src = canvas.toDataURL();
+  return img;
+};
+
+var insertImage = function(element, caption, img) {
+  var div = document.createElement("div");
+  div.appendChild(img);
+  var label = document.createElement("div");
+  label.appendChild(document.createTextNode(caption));
+  div.appendChild(label);
+   element.appendChild(div);
+};
+
+var addShaderSource = function(element, label, source, opt_url) {
+  var div = document.createElement("div");
+  var s = document.createElement("pre");
+  s.className = "shader-source";
+  s.style.display = "none";
+  var ol = document.createElement("ol");
+  //s.appendChild(document.createTextNode(source));
+  var lines = source.split("\n");
+  for (var ii = 0; ii < lines.length; ++ii) {
+    var line = lines[ii];
+    var li = document.createElement("li");
+    li.appendChild(document.createTextNode(line));
+    ol.appendChild(li);
+  }
+  s.appendChild(ol);
+  var l = document.createElement("a");
+  l.href = "show-shader-source";
+  l.appendChild(document.createTextNode(label));
+  l.addEventListener('click', function(event) {
+      if (event.preventDefault) {
+        event.preventDefault();
+      }
+      s.style.display = (s.style.display == 'none') ? 'block' : 'none';
+      return false;
+    }, false);
+  div.appendChild(l);
+  if (opt_url) {
+    var u = document.createElement("a");
+    u.href = opt_url;
+    div.appendChild(document.createTextNode(" "));
+    u.appendChild(document.createTextNode("(" + opt_url + ")"));
+    div.appendChild(u);
+  }
+  div.appendChild(s);
+  element.appendChild(div);
+};
+
+// Add your prefix here.
+var browserPrefixes = [
+  "",
+  "MOZ_",
+  "OP_",
+  "WEBKIT_"
+];
+
+/**
+ * Given an extension name like WEBGL_compressed_texture_s3tc
+ * returns the name of the supported version extension, like
+ * WEBKIT_WEBGL_compressed_teture_s3tc
+ * @param {string} name Name of extension to look for
+ * @return {string} name of extension found or undefined if not
+ *     found.
+ */
+var getSupportedExtensionWithKnownPrefixes = function(gl, name) {
+  var supported = gl.getSupportedExtensions();
+  for (var ii = 0; ii < browserPrefixes.length; ++ii) {
+    var prefixedName = browserPrefixes[ii] + name;
+    if (supported.indexOf(prefixedName) >= 0) {
+      return prefixedName;
+    }
+  }
+};
+
+/**
+ * Given an extension name like WEBGL_compressed_texture_s3tc
+ * returns the supported version extension, like
+ * WEBKIT_WEBGL_compressed_teture_s3tc
+ * @param {string} name Name of extension to look for
+ * @return {WebGLExtension} The extension or undefined if not
+ *     found.
+ */
+var getExtensionWithKnownPrefixes = function(gl, name) {
+  for (var ii = 0; ii < browserPrefixes.length; ++ii) {
+    var prefixedName = browserPrefixes[ii] + name;
+    var ext = gl.getExtension(prefixedName);
+    if (ext) {
+      return ext;
+    }
+  }
+};
+
+
+var replaceRE = /\$\((\w+)\)/g;
+
+/**
+ * Replaces strings with property values.
+ * Given a string like "hello $(first) $(last)" and an object
+ * like {first:"John", last:"Smith"} will return
+ * "hello John Smith".
+ * @param {string} str String to do replacements in
+ * @param {...} 1 or more objects conaining properties.
+ */
+var replaceParams = function(str) {
+  var args = arguments;
+  return str.replace(replaceRE, function(str, p1, offset, s) {
+    for (var ii = 1; ii < args.length; ++ii) {
+      if (args[ii][p1] !== undefined) {
+        return args[ii][p1];
+      }
+    }
+    throw "unknown string param '" + p1 + "'";
+  });
+};
+
+
+/**
+ * Provides requestAnimationFrame in a cross browser way.
+ */
+var requestAnimFrameImpl_;
+
+var requestAnimFrame = function(callback, element) {
+  if (!requestAnimFrameImpl_) {
+    requestAnimFrameImpl_ = function() {
+      var functionNames = [
+        "requestAnimationFrame",
+        "webkitRequestAnimationFrame",
+        "mozRequestAnimationFrame",
+        "oRequestAnimationFrame",
+        "msRequestAnimationFrame"
+      ];
+      for (var jj = 0; jj < functionNames.length; ++jj) {
+        var functionName = functionNames[jj];
+        if (window[functionName]) {
+          return function(name) {
+            return function(callback, element) {
+              return window[name].call(window, callback, element);
+            };
+          }(functionName);
+        }
+      }
+      return function(callback, element) {
+           return window.setTimeout(callback, 1000 / 70);
+        };
+    }();
+  }
+
+  return requestAnimFrameImpl_(callback, element);
+};
+
+/**
+ * Provides cancelAnimationFrame in a cross browser way.
+ */
+var cancelAnimFrame = (function() {
+  return window.cancelAnimationFrame ||
+         window.webkitCancelAnimationFrame ||
+         window.mozCancelAnimationFrame ||
+         window.oCancelAnimationFrame ||
+         window.msCancelAnimationFrame ||
+         window.clearTimeout;
+})();
+
+var waitFrames = function(frames, callback) {
+  var countDown = function() {
+    if (frames == 0) {
+      callback();
+    } else {
+      --frames;
+      requestAnimFrame(countDown);
+    }
+  };
+  countDown();
+};
+
+return {
+  addShaderSource: addShaderSource,
+  cancelAnimFrame: cancelAnimFrame,
+  create3DContext: create3DContext,
+  create3DContextWithWrapperThatThrowsOnGLError:
+    create3DContextWithWrapperThatThrowsOnGLError,
+  checkCanvas: checkCanvas,
+  checkCanvasRect: checkCanvasRect,
+  createColoredTexture: createColoredTexture,
+  createProgram: createProgram,
+  drawQuad: drawQuad,
+  drawIndexedQuad: drawIndexedQuad,
+  endsWith: endsWith,
+  getExtensionWithKnownPrefixes: getExtensionWithKnownPrefixes,
+  getFileListAsync: getFileListAsync,
+  getLastError: getLastError,
+  getScript: getScript,
+  getSupportedExtensionWithKnownPrefixes: getSupportedExtensionWithKnownPrefixes,
+  getUrlArguments: getUrlArguments,
+  glEnumToString: glEnumToString,
+  glErrorShouldBe: glErrorShouldBe,
+  fillTexture: fillTexture,
+  insertImage: insertImage,
+  loadImageAsync: loadImageAsync,
+  loadImagesAsync: loadImagesAsync,
+  loadProgram: loadProgram,
+  loadProgramFromFile: loadProgramFromFile,
+  loadProgramFromScript: loadProgramFromScript,
+  loadProgramFromScriptExpectError: loadProgramFromScriptExpectError,
+  loadShader: loadShader,
+  loadShaderFromFile: loadShaderFromFile,
+  loadShaderFromScript: loadShaderFromScript,
+  loadStandardProgram: loadStandardProgram,
+  loadStandardVertexShader: loadStandardVertexShader,
+  loadStandardFragmentShader: loadStandardFragmentShader,
+  loadTextFileAsync: loadTextFileAsync,
+  loadTexture: loadTexture,
+  log: log,
+  loggingOff: loggingOff,
+  makeImage: makeImage,
+  error: error,
+  setupColorQuad: setupColorQuad,
+  setupProgram: setupProgram,
+  setupQuad: setupQuad,
+  setupQuadWithOptions: setupQuadWithOptions,
+  setupSimpleTextureFragmentShader: setupSimpleTextureFragmentShader,
+  setupSimpleTextureProgram: setupSimpleTextureProgram,
+  setupSimpleTextureVertexShader: setupSimpleTextureVertexShader,
+  setupNoTexCoordTextureProgram: setupNoTexCoordTextureProgram,
+  setupNoTexCoordTextureVertexShader: setupNoTexCoordTextureVertexShader,
+  setupTexturedQuad: setupTexturedQuad,
+  setupTexturedQuadWithTexCoords: setupTexturedQuadWithTexCoords,
+  setupUnitQuad: setupUnitQuad,
+  setupUnitQuadWithTexCoords: setupUnitQuadWithTexCoords,
+  startsWith: startsWith,
+  shouldGenerateGLError: shouldGenerateGLError,
+  readFile: readFile,
+  readFileList: readFileList,
+  replaceParams: replaceParams,
+  requestAnimFrame: requestAnimFrame,
+  waitFrames: waitFrames,
+
+  none: false
+};
+
+}());
+
+