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

third_party/webgl/sdk/tests/conformance/resources/glsl-generator.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.
+*/
+GLSLGenerator = (function() {
+
+var vertexShaderTemplate = [
+  "attribute vec4 aPosition;",
+  "",
+  "varying vec4 vColor;",
+  "",
+  "$(extra)",
+  "$(emu)",
+  "",
+  "void main()",
+  "{",
+  "   gl_Position = aPosition;",
+  "   vec2 texcoord = vec2(aPosition.xy * 0.5 + vec2(0.5, 0.5));",
+  "   vec4 color = vec4(",
+  "       texcoord,",
+  "       texcoord.x * texcoord.y,",
+  "       (1.0 - texcoord.x) * texcoord.y * 0.5 + 0.5);",
+  "   $(test)",
+  "}"
+].join("\n");
+
+var fragmentShaderTemplate = [
+  "#if defined(GL_ES)",
+  "precision mediump float;",
+  "#endif",
+  "",
+  "varying vec4 vColor;",
+  "",
+  "$(extra)",
+  "$(emu)",
+  "",
+  "void main()",
+  "{",
+  "   $(test)",
+  "}"
+].join("\n");
+
+var baseVertexShader = [
+  "attribute vec4 aPosition;",
+  "",
+  "varying vec4 vColor;",
+  "",
+  "void main()",
+  "{",
+  "   gl_Position = aPosition;",
+  "   vec2 texcoord = vec2(aPosition.xy * 0.5 + vec2(0.5, 0.5));",
+  "   vColor = vec4(",
+  "       texcoord,",
+  "       texcoord.x * texcoord.y,",
+  "       (1.0 - texcoord.x) * texcoord.y * 0.5 + 0.5);",
+  "}"
+].join("\n");
+
+var baseFragmentShader = [
+  "#if defined(GL_ES)",
+  "precision mediump float;",
+  "#endif",
+  "varying vec4 vColor;",
+  "",
+  "void main()",
+  "{",
+  "   gl_FragColor = vColor;",
+  "}"
+].join("\n");
+
+var types = [
+  { type: "float",
+    code: [
+      "float $(func)_emu($(args)) {",
+      "  return $(func)_base($(baseArgs));",
+      "}"].join("\n")
+  },
+  { type: "vec2",
+    code: [
+      "vec2 $(func)_emu($(args)) {",
+      "  return vec2(",
+      "      $(func)_base($(baseArgsX)),",
+      "      $(func)_base($(baseArgsY)));",
+      "}"].join("\n")
+  },
+  { type: "vec3",
+    code: [
+      "vec3 $(func)_emu($(args)) {",
+      "  return vec3(",
+      "      $(func)_base($(baseArgsX)),",
+      "      $(func)_base($(baseArgsY)),",
+      "      $(func)_base($(baseArgsZ)));",
+      "}"].join("\n")
+  },
+  { type: "vec4",
+    code: [
+      "vec4 $(func)_emu($(args)) {",
+      "  return vec4(",
+      "      $(func)_base($(baseArgsX)),",
+      "      $(func)_base($(baseArgsY)),",
+      "      $(func)_base($(baseArgsZ)),",
+      "      $(func)_base($(baseArgsW)));",
+      "}"].join("\n")
+  }
+];
+
+var bvecTypes = [
+  { type: "bvec2",
+    code: [
+      "bvec2 $(func)_emu($(args)) {",
+      "  return bvec2(",
+      "      $(func)_base($(baseArgsX)),",
+      "      $(func)_base($(baseArgsY)));",
+      "}"].join("\n")
+  },
+  { type: "bvec3",
+    code: [
+      "bvec3 $(func)_emu($(args)) {",
+      "  return bvec3(",
+      "      $(func)_base($(baseArgsX)),",
+      "      $(func)_base($(baseArgsY)),",
+      "      $(func)_base($(baseArgsZ)));",
+      "}"].join("\n")
+  },
+  { type: "bvec4",
+    code: [
+      "vec4 $(func)_emu($(args)) {",
+      "  return bvec4(",
+      "      $(func)_base($(baseArgsX)),",
+      "      $(func)_base($(baseArgsY)),",
+      "      $(func)_base($(baseArgsZ)),",
+      "      $(func)_base($(baseArgsW)));",
+      "}"].join("\n")
+  }
+];
+
+var replaceRE = /\$\((\w+)\)/g;
+
+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 + "'";
+  });
+};
+
+var generateReferenceShader = function(
+    shaderInfo, template, params, typeInfo, test) {
+  var input = shaderInfo.input;
+  var output = shaderInfo.output;
+  var feature = params.feature;
+  var testFunc = params.testFunc;
+  var emuFunc = params.emuFunc || "";
+  var extra = params.extra || '';
+  var args = params.args || "$(type) value";
+  var type = typeInfo.type;
+  var typeCode = typeInfo.code;
+
+  var baseArgs = params.baseArgs || "value$(field)";
+  var baseArgsX = replaceParams(baseArgs, {field: ".x"});
+  var baseArgsY = replaceParams(baseArgs, {field: ".y"});
+  var baseArgsZ = replaceParams(baseArgs, {field: ".z"});
+  var baseArgsW = replaceParams(baseArgs, {field: ".w"});
+  var baseArgs = replaceParams(baseArgs, {field: ""});
+
+  test = replaceParams(test, {
+    input: input,
+    output: output,
+    func: feature + "_emu"
+  });
+  emuFunc = replaceParams(emuFunc, {
+    func: feature
+  });
+  args = replaceParams(args, {
+    type: type
+  });
+  typeCode = replaceParams(typeCode, {
+    func: feature,
+    type: type,
+    args: args,
+    baseArgs: baseArgs,
+    baseArgsX: baseArgsX,
+    baseArgsY: baseArgsY,
+    baseArgsZ: baseArgsZ,
+    baseArgsW: baseArgsW
+  });
+  var shader = replaceParams(template, {
+    extra: extra,
+    emu: emuFunc + "\n\n" + typeCode,
+    test: test
+  });
+  return shader;
+};
+
+var generateTestShader = function(
+    shaderInfo, template, params, test) {
+  var input = shaderInfo.input;
+  var output = shaderInfo.output;
+  var feature = params.feature;
+  var testFunc = params.testFunc;
+  var extra = params.extra || '';
+
+  test = replaceParams(test, {
+    input: input,
+    output: output,
+    func: feature
+  });
+  var shader = replaceParams(template, {
+    extra: extra,
+    emu: '',
+    test: test
+  });
+  return shader;
+};
+
+var runFeatureTest = function(params) {
+  if (window.initNonKhronosFramework) {
+    window.initNonKhronosFramework(false);
+  }
+
+  var wtu = WebGLTestUtils;
+  var gridRes = params.gridRes;
+  var vertexTolerance = params.tolerance || 0;
+  var fragmentTolerance = vertexTolerance;
+  if ('fragmentTolerance' in params)
+    fragmentTolerance = params.fragmentTolerance || 0;
+
+  description("Testing GLSL feature: " + params.feature);
+
+  var width = 32;
+  var height = 32;
+
+  var console = document.getElementById("console");
+  var canvas = document.createElement('canvas');
+  canvas.width = width;
+  canvas.height = height;
+  var gl = wtu.create3DContext(canvas);
+  if (!gl) {
+    testFailed("context does not exist");
+    finishTest();
+    return;
+  }
+
+  var canvas2d = document.createElement('canvas');
+  canvas2d.width = width;
+  canvas2d.height = height;
+  var ctx = canvas2d.getContext("2d");
+  var imgData = ctx.getImageData(0, 0, width, height);
+
+  var shaderInfos = [
+    { type: "vertex",
+      input: "color",
+      output: "vColor",
+      vertexShaderTemplate: vertexShaderTemplate,
+      fragmentShaderTemplate: baseFragmentShader,
+      tolerance: vertexTolerance
+    },
+    { type: "fragment",
+      input: "vColor",
+      output: "gl_FragColor",
+      vertexShaderTemplate: baseVertexShader,
+      fragmentShaderTemplate: fragmentShaderTemplate,
+      tolerance: fragmentTolerance
+    }
+  ];
+  for (var ss = 0; ss < shaderInfos.length; ++ss) {
+    var shaderInfo = shaderInfos[ss];
+    var tests = params.tests;
+    var testTypes = params.emuFuncs || (params.bvecTest ? bvecTypes : types);
+    // Test vertex shaders
+    for (var ii = 0; ii < tests.length; ++ii) {
+      var type = testTypes[ii];
+      if (params.simpleEmu) {
+        type = {
+          type: type.type,
+          code: params.simpleEmu
+        };
+      }
+      debug("");
+      var str = replaceParams(params.testFunc, {
+        func: params.feature,
+        type: type.type,
+        arg0: type.type
+      });
+      debug("Testing: " + str + " in " + shaderInfo.type + " shader");
+
+      var referenceVertexShaderSource = generateReferenceShader(
+          shaderInfo,
+          shaderInfo.vertexShaderTemplate,
+          params,
+          type,
+          tests[ii]);
+      var referenceFragmentShaderSource = generateReferenceShader(
+          shaderInfo,
+          shaderInfo.fragmentShaderTemplate,
+          params,
+          type,
+          tests[ii]);
+      var testVertexShaderSource = generateTestShader(
+          shaderInfo,
+          shaderInfo.vertexShaderTemplate,
+          params,
+          tests[ii]);
+      var testFragmentShaderSource = generateTestShader(
+          shaderInfo,
+          shaderInfo.fragmentShaderTemplate,
+          params,
+          tests[ii]);
+
+      debug("");
+      wtu.addShaderSource(
+          console, "reference vertex shader", referenceVertexShaderSource);
+      wtu.addShaderSource(
+          console, "reference fragment shader", referenceFragmentShaderSource);
+      wtu.addShaderSource(
+          console, "test vertex shader", testVertexShaderSource);
+      wtu.addShaderSource(
+          console, "test fragment shader", testFragmentShaderSource);
+      debug("");
+
+      var refData = draw(
+          canvas, referenceVertexShaderSource, referenceFragmentShaderSource);
+      var refImg = wtu.makeImage(canvas);
+      if (ss == 0) {
+        var testData = draw(
+            canvas, testVertexShaderSource, referenceFragmentShaderSource);
+      } else {
+        var testData = draw(
+            canvas, referenceVertexShaderSource, testFragmentShaderSource);
+      }
+      var testImg = wtu.makeImage(canvas);
+
+      reportResults(refData, refImg, testData, testImg, shaderInfo.tolerance);
+    }
+  }
+
+  finishTest();
+
+  function reportResults(refData, refImage, testData, testImage, tolerance) {
+    var same = true;
+    for (var yy = 0; yy < height; ++yy) {
+      for (var xx = 0; xx < width; ++xx) {
+        var offset = (yy * width + xx) * 4;
+        var imgOffset = ((height - yy - 1) * width + xx) * 4;
+        imgData.data[imgOffset + 0] = 0;
+        imgData.data[imgOffset + 1] = 0;
+        imgData.data[imgOffset + 2] = 0;
+        imgData.data[imgOffset + 3] = 255;
+        if (Math.abs(refData[offset + 0] - testData[offset + 0]) > tolerance ||
+            Math.abs(refData[offset + 1] - testData[offset + 1]) > tolerance ||
+            Math.abs(refData[offset + 2] - testData[offset + 2]) > tolerance ||
+            Math.abs(refData[offset + 3] - testData[offset + 3]) > tolerance) {
+          imgData.data[imgOffset] = 255;
+          same = false;
+        }
+      }
+    }
+
+    var diffImg = null;
+    if (!same) {
+      ctx.putImageData(imgData, 0, 0);
+      diffImg = wtu.makeImage(canvas2d);
+    }
+
+    var div = document.createElement("div");
+    div.className = "testimages";
+    wtu.insertImage(div, "ref", refImg);
+    wtu.insertImage(div, "test", testImg);
+    if (diffImg) {
+      wtu.insertImage(div, "diff", diffImg);
+    }
+    div.appendChild(document.createElement('br'));
+
+
+    console.appendChild(div);
+
+    if (!same) {
+      testFailed("images are different");
+    } else {
+      testPassed("images are the same");
+    }
+
+    console.appendChild(document.createElement('hr'));
+  }
+
+  function draw(canvas, vsSource, fsSource) {
+    var program = wtu.loadProgram(gl, vsSource, fsSource, testFailed);
+
+    var posLoc = gl.getAttribLocation(program, "aPosition");
+    WebGLTestUtils.setupQuad(gl, gridRes, posLoc);
+
+    gl.useProgram(program);
+    gl.clearColor(0, 0, 1, 1);
+    gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
+    gl.drawElements(gl.TRIANGLES, gridRes * gridRes * 6, gl.UNSIGNED_SHORT, 0);
+    wtu.glErrorShouldBe(gl, gl.NO_ERROR, "no errors from draw");
+
+    var img = new Uint8Array(width * height * 4);
+    gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, img);
+    return img;
+  }
+
+};
+
+var runBasicTest = function(params) {
+  if (window.initNonKhronosFramework) {
+    window.initNonKhronosFramework(false);
+  }
+
+  var wtu = WebGLTestUtils;
+  var gridRes = params.gridRes;
+  var vertexTolerance = params.tolerance || 0;
+  var fragmentTolerance = vertexTolerance;
+  if ('fragmentTolerance' in params)
+    fragmentTolerance = params.fragmentTolerance || 0;
+
+  description("Testing : " + document.getElementsByTagName("title")[0].innerText);
+
+  var width = 32;
+  var height = 32;
+
+  var console = document.getElementById("console");
+  var canvas = document.createElement('canvas');
+  canvas.width = width;
+  canvas.height = height;
+  var gl = wtu.create3DContext(canvas);
+  if (!gl) {
+    testFailed("context does not exist");
+    finishTest();
+    return;
+  }
+
+  var canvas2d = document.createElement('canvas');
+  canvas2d.width = width;
+  canvas2d.height = height;
+  var ctx = canvas2d.getContext("2d");
+  var imgData = ctx.getImageData(0, 0, width, height);
+
+  var shaderInfos = [
+    { type: "vertex",
+      input: "color",
+      output: "vColor",
+      vertexShaderTemplate: vertexShaderTemplate,
+      fragmentShaderTemplate: baseFragmentShader,
+      tolerance: vertexTolerance
+    },
+    { type: "fragment",
+      input: "vColor",
+      output: "gl_FragColor",
+      vertexShaderTemplate: baseVertexShader,
+      fragmentShaderTemplate: fragmentShaderTemplate,
+      tolerance: fragmentTolerance
+    }
+  ];
+  for (var ss = 0; ss < shaderInfos.length; ++ss) {
+    var shaderInfo = shaderInfos[ss];
+    var tests = params.tests;
+//    var testTypes = params.emuFuncs || (params.bvecTest ? bvecTypes : types);
+    // Test vertex shaders
+    for (var ii = 0; ii < tests.length; ++ii) {
+      var test = tests[ii];
+      debug("");
+      debug("Testing: " + test.name + " in " + shaderInfo.type + " shader");
+
+      function genShader(shaderInfo, template, shader, subs) {
+        shader = replaceParams(shader, subs, {
+            input: shaderInfo.input,
+            output: shaderInfo.output
+          });
+        shader = replaceParams(template, subs, {
+            test: shader,
+            emu: "",
+            extra: ""
+          });
+        return shader;
+      }
+
+      var referenceVertexShaderSource = genShader(
+          shaderInfo,
+          shaderInfo.vertexShaderTemplate,
+          test.reference.shader,
+          test.reference.subs);
+      var referenceFragmentShaderSource = genShader(
+          shaderInfo,
+          shaderInfo.fragmentShaderTemplate,
+          test.reference.shader,
+          test.reference.subs);
+      var testVertexShaderSource = genShader(
+          shaderInfo,
+          shaderInfo.vertexShaderTemplate,
+          test.test.shader,
+          test.test.subs);
+      var testFragmentShaderSource = genShader(
+          shaderInfo,
+          shaderInfo.fragmentShaderTemplate,
+          test.test.shader,
+          test.test.subs);
+
+      debug("");
+      wtu.addShaderSource(
+          console, "reference vertex shader", referenceVertexShaderSource);
+      wtu.addShaderSource(
+          console, "reference fragment shader", referenceFragmentShaderSource);
+      wtu.addShaderSource(
+          console, "test vertex shader", testVertexShaderSource);
+      wtu.addShaderSource(
+          console, "test fragment shader", testFragmentShaderSource);
+      debug("");
+
+      var refData = draw(
+          canvas, referenceVertexShaderSource, referenceFragmentShaderSource);
+      var refImg = wtu.makeImage(canvas);
+      if (ss == 0) {
+        var testData = draw(
+            canvas, testVertexShaderSource, referenceFragmentShaderSource);
+      } else {
+        var testData = draw(
+            canvas, referenceVertexShaderSource, testFragmentShaderSource);
+      }
+      var testImg = wtu.makeImage(canvas);
+
+      reportResults(refData, refImg, testData, testImg, shaderInfo.tolerance);
+    }
+  }
+
+  finishTest();
+
+  function reportResults(refData, refImage, testData, testImage, tolerance) {
+    var same = true;
+    for (var yy = 0; yy < height; ++yy) {
+      for (var xx = 0; xx < width; ++xx) {
+        var offset = (yy * width + xx) * 4;
+        var imgOffset = ((height - yy - 1) * width + xx) * 4;
+        imgData.data[imgOffset + 0] = 0;
+        imgData.data[imgOffset + 1] = 0;
+        imgData.data[imgOffset + 2] = 0;
+        imgData.data[imgOffset + 3] = 255;
+        if (Math.abs(refData[offset + 0] - testData[offset + 0]) > tolerance ||
+            Math.abs(refData[offset + 1] - testData[offset + 1]) > tolerance ||
+            Math.abs(refData[offset + 2] - testData[offset + 2]) > tolerance ||
+            Math.abs(refData[offset + 3] - testData[offset + 3]) > tolerance) {
+          imgData.data[imgOffset] = 255;
+          same = false;
+        }
+      }
+    }
+
+    var diffImg = null;
+    if (!same) {
+      ctx.putImageData(imgData, 0, 0);
+      diffImg = wtu.makeImage(canvas2d);
+    }
+
+    var div = document.createElement("div");
+    div.className = "testimages";
+    wtu.insertImage(div, "ref", refImg);
+    wtu.insertImage(div, "test", testImg);
+    if (diffImg) {
+      wtu.insertImage(div, "diff", diffImg);
+    }
+    div.appendChild(document.createElement('br'));
+
+    console.appendChild(div);
+
+    if (!same) {
+      testFailed("images are different");
+    } else {
+      testPassed("images are the same");
+    }
+
+    console.appendChild(document.createElement('hr'));
+  }
+
+  function draw(canvas, vsSource, fsSource) {
+    var program = wtu.loadProgram(gl, vsSource, fsSource, testFailed);
+
+    var posLoc = gl.getAttribLocation(program, "aPosition");
+    WebGLTestUtils.setupQuad(gl, gridRes, posLoc);
+
+    gl.useProgram(program);
+    gl.clearColor(0, 0, 1, 1);
+    gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
+    gl.drawElements(gl.TRIANGLES, gridRes * gridRes * 6, gl.UNSIGNED_SHORT, 0);
+    wtu.glErrorShouldBe(gl, gl.NO_ERROR, "no errors from draw");
+
+    var img = new Uint8Array(width * height * 4);
+    gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, img);
+    return img;
+  }
+
+};
+
+var runReferenceImageTest = function(params) {
+  if (window.initNonKhronosFramework) {
+    window.initNonKhronosFramework(false);
+  }
+
+  var wtu = WebGLTestUtils;
+  var gridRes = params.gridRes;
+  var vertexTolerance = params.tolerance || 0;
+  var fragmentTolerance = vertexTolerance;
+  if ('fragmentTolerance' in params)
+    fragmentTolerance = params.fragmentTolerance || 0;
+
+  description("Testing GLSL feature: " + params.feature);
+
+  var width = 32;
+  var height = 32;
+
+  var console = document.getElementById("console");
+  var canvas = document.createElement('canvas');
+  canvas.width = width;
+  canvas.height = height;
+  var gl = wtu.create3DContext(canvas, { antialias: false });
+  if (!gl) {
+    testFailed("context does not exist");
+    finishTest();
+    return;
+  }
+
+  var canvas2d = document.createElement('canvas');
+  canvas2d.width = width;
+  canvas2d.height = height;
+  var ctx = canvas2d.getContext("2d");
+  var imgData = ctx.getImageData(0, 0, width, height);
+
+  var shaderInfos = [
+    { type: "vertex",
+      input: "color",
+      output: "vColor",
+      vertexShaderTemplate: vertexShaderTemplate,
+      fragmentShaderTemplate: baseFragmentShader,
+      tolerance: vertexTolerance
+    },
+    { type: "fragment",
+      input: "vColor",
+      output: "gl_FragColor",
+      vertexShaderTemplate: baseVertexShader,
+      fragmentShaderTemplate: fragmentShaderTemplate,
+      tolerance: fragmentTolerance
+    }
+  ];
+  for (var ss = 0; ss < shaderInfos.length; ++ss) {
+    var shaderInfo = shaderInfos[ss];
+    var tests = params.tests;
+    var testTypes = params.emuFuncs || (params.bvecTest ? bvecTypes : types);
+    // Test vertex shaders
+    for (var ii = 0; ii < tests.length; ++ii) {
+      var type = testTypes[ii];
+      var isVertex = (ss == 0);
+      debug("");
+      var str = replaceParams(params.testFunc, {
+        func: params.feature,
+        type: type.type,
+        arg0: type.type
+      });
+      debug("Testing: " + str + " in " + shaderInfo.type + " shader");
+
+      var referenceVertexShaderSource = generateReferenceShader(
+          shaderInfo,
+          shaderInfo.vertexShaderTemplate,
+          params,
+          type,
+          tests[ii].source);
+      var referenceFragmentShaderSource = generateReferenceShader(
+          shaderInfo,
+          shaderInfo.fragmentShaderTemplate,
+          params,
+          type,
+          tests[ii].source);
+      var testVertexShaderSource = generateTestShader(
+          shaderInfo,
+          shaderInfo.vertexShaderTemplate,
+          params,
+          tests[ii].source);
+      var testFragmentShaderSource = generateTestShader(
+          shaderInfo,
+          shaderInfo.fragmentShaderTemplate,
+          params,
+          tests[ii].source);
+      var referenceTexture = generateReferenceTexture(
+          gl,
+          tests[ii].generator,
+          isVertex ? gridRes : width,
+          isVertex ? gridRes : height,
+          isVertex);
+
+      debug("");
+      wtu.addShaderSource(
+          console, "test vertex shader", testVertexShaderSource);
+      wtu.addShaderSource(
+          console, "test fragment shader", testFragmentShaderSource);
+      debug("");
+      var refData = drawReferenceImage(canvas, referenceTexture, isVertex);
+      var refImg = wtu.makeImage(canvas);
+      if (isVertex) {
+        var testData = draw(
+            canvas, testVertexShaderSource, referenceFragmentShaderSource);
+      } else {
+        var testData = draw(
+            canvas, referenceVertexShaderSource, testFragmentShaderSource);
+      }
+      var testImg = wtu.makeImage(canvas);
+      var testTolerance = shaderInfo.tolerance;
+      // Provide per-test tolerance so that we can increase it only for those desired.
+      if ('tolerance' in tests[ii])
+        testTolerance = tests[ii].tolerance || 0;
+      reportResults(refData, refImg, testData, testImg, testTolerance);
+    }
+  }
+
+  finishTest();
+
+  function reportResults(refData, refImage, testData, testImage, tolerance) {
+    var same = true;
+    for (var yy = 0; yy < height; ++yy) {
+      for (var xx = 0; xx < width; ++xx) {
+        var offset = (yy * width + xx) * 4;
+        var imgOffset = ((height - yy - 1) * width + xx) * 4;
+        imgData.data[imgOffset + 0] = 0;
+        imgData.data[imgOffset + 1] = 0;
+        imgData.data[imgOffset + 2] = 0;
+        imgData.data[imgOffset + 3] = 255;
+        if (Math.abs(refData[offset + 0] - testData[offset + 0]) > tolerance ||
+            Math.abs(refData[offset + 1] - testData[offset + 1]) > tolerance ||
+            Math.abs(refData[offset + 2] - testData[offset + 2]) > tolerance ||
+            Math.abs(refData[offset + 3] - testData[offset + 3]) > tolerance) {
+          console.appendChild(document.createTextNode('at (' + xx + ',' + yy + '): ref=(' +
+                                                      refData[offset + 0] + ',' +
+                                                      refData[offset + 1] + ',' +
+                                                      refData[offset + 2] + ',' +
+                                                      refData[offset + 3] + ')  test=(' +
+                                                      testData[offset + 0] + ',' +
+                                                      testData[offset + 1] + ',' +
+                                                      testData[offset + 2] + ',' +
+                                                      testData[offset + 3] + ')'));
+          console.appendChild(document.createElement('br'));          
+
+
+
+          imgData.data[imgOffset] = 255;
+          same = false;
+        }
+      }
+    }
+
+    var diffImg = null;
+    if (!same) {
+      ctx.putImageData(imgData, 0, 0);
+      diffImg = wtu.makeImage(canvas2d);
+    }
+
+    var div = document.createElement("div");
+    div.className = "testimages";
+    wtu.insertImage(div, "ref", refImg);
+    wtu.insertImage(div, "test", testImg);
+    if (diffImg) {
+      wtu.insertImage(div, "diff", diffImg);
+    }
+    div.appendChild(document.createElement('br'));
+
+    console.appendChild(div);
+
+    if (!same) {
+      testFailed("images are different");
+    } else {
+      testPassed("images are the same");
+    }
+
+    console.appendChild(document.createElement('hr'));
+  }
+
+  function draw(canvas, vsSource, fsSource) {
+    var program = wtu.loadProgram(gl, vsSource, fsSource, testFailed);
+
+    var posLoc = gl.getAttribLocation(program, "aPosition");
+    WebGLTestUtils.setupQuad(gl, gridRes, posLoc);
+
+    gl.useProgram(program);
+    gl.clearColor(0, 0, 1, 1);
+    gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
+    gl.drawElements(gl.TRIANGLES, gridRes * gridRes * 6, gl.UNSIGNED_SHORT, 0);
+    wtu.glErrorShouldBe(gl, gl.NO_ERROR, "no errors from draw");
+
+    var img = new Uint8Array(width * height * 4);
+    gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, img);
+    return img;
+  }
+
+  function drawReferenceImage(canvas, texture, isVertex) {
+    var program;
+    if (isVertex) {
+      var halfTexel = 0.5 / (1.0 + gridRes);
+      program = WebGLTestUtils.setupTexturedQuadWithTexCoords(
+        gl, [halfTexel, halfTexel], [1.0 - halfTexel, 1.0 - halfTexel]);
+    } else {
+      program = WebGLTestUtils.setupTexturedQuad(gl);
+    }
+
+    gl.activeTexture(gl.TEXTURE0);
+    gl.bindTexture(gl.TEXTURE_2D, texture);
+    var texLoc = gl.getUniformLocation(program, "tex");
+    gl.uniform1i(texLoc, 0);
+    wtu.drawQuad(gl);
+    wtu.glErrorShouldBe(gl, gl.NO_ERROR, "no errors from draw");
+
+    var img = new Uint8Array(width * height * 4);
+    gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, img);
+    return img;
+  }
+
+  /**
+   * Creates and returns a texture containing the reference image for
+   * the function being tested. Exactly how the function is evaluated,
+   * and the size of the returned texture, depends on whether we are
+   * testing a vertex or fragment shader. If a fragment shader, the
+   * function is evaluated at the pixel centers. If a vertex shader,
+   * the function is evaluated at the triangle's vertices, and the
+   * resulting texture must be offset by half a texel during
+   * rendering.
+   *
+   * @param {!WebGLRenderingContext} gl The WebGLRenderingContext to use to generate texture objects.
+   * @param {!function(number,number,number,number): !Array.<number>} generator The reference image generator function.
+   * @param {number} width The width of the texture to generate if testing a fragment shader; the grid resolution if testing a vertex shader.
+   * @param {number} height The height of the texture to generate if testing a fragment shader; the grid resolution if testing a vertex shader.
+   * @param {boolean} isVertex True if generating a reference image for a vertex shader; false if for a fragment shader.
+   * @return {!WebGLTexture} The texture object that was generated.
+   */
+  function generateReferenceTexture(
+    gl,
+    generator,
+    width,
+    height,
+    isVertex) {
+
+    // Note: the math in this function must match that in the vertex and
+    // fragment shader templates above.
+    function computeTexCoord(x) {
+      return x * 0.5 + 0.5;
+    }
+
+    function computeColor(texCoordX, texCoordY) {
+      return [ texCoordX,
+               texCoordY,
+               texCoordX * texCoordY,
+               (1.0 - texCoordX) * texCoordY * 0.5 + 0.5 ];
+    }
+
+    function clamp(value, minVal, maxVal) {
+      return Math.max(minVal, Math.min(value, maxVal));
+    }
+
+    // Evaluates the function at clip coordinates (px,py), storing the
+    // result in the array "pixel". Each channel's result is clamped
+    // between 0 and 255.
+    function evaluateAtClipCoords(px, py, pixel) {
+      var tcx = computeTexCoord(px);
+      var tcy = computeTexCoord(py);
+
+      var color = computeColor(tcx, tcy);
+
+      var output = generator(color[0], color[1], color[2], color[3]);
+
+      // Multiply by 256 to get even distribution for all values between 0 and 1.
+      // Use rounding rather than truncation to more closely match the GPU's behavior.
+      pixel[0] = clamp(Math.round(256 * output[0]), 0, 255);
+      pixel[1] = clamp(Math.round(256 * output[1]), 0, 255);
+      pixel[2] = clamp(Math.round(256 * output[2]), 0, 255);
+      pixel[3] = clamp(Math.round(256 * output[3]), 0, 255);
+    }
+
+    function fillFragmentReference() {
+      var data = new Uint8Array(4 * width * height);
+
+      var horizTexel = 1.0 / width;
+      var vertTexel = 1.0 / height;
+      var halfHorizTexel = 0.5 * horizTexel;
+      var halfVertTexel = 0.5 * vertTexel;
+
+      var pixel = new Array(4);
+
+      for (var yi = 0; yi < height; ++yi) {
+        for (var xi = 0; xi < width; ++xi) {
+          // The function must be evaluated at pixel centers.
+
+          // Compute desired position in clip space
+          var px = -1.0 + 2.0 * (halfHorizTexel + xi * horizTexel);
+          var py = -1.0 + 2.0 * (halfVertTexel + yi * vertTexel);
+
+          evaluateAtClipCoords(px, py, pixel);
+          var index = 4 * (width * yi + xi);
+          data[index + 0] = pixel[0];
+          data[index + 1] = pixel[1];
+          data[index + 2] = pixel[2];
+          data[index + 3] = pixel[3];
+        }
+      }
+
+      gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, width, height, 0,
+                    gl.RGBA, gl.UNSIGNED_BYTE, data);
+    }
+
+    function fillVertexReference() {
+      // We generate a texture which contains the evaluation of the
+      // function at the vertices of the triangle mesh. It is expected
+      // that the width and the height are identical, and equivalent
+      // to the grid resolution.
+      if (width != height) {
+        throw "width and height must be equal";
+      }
+
+      var texSize = 1 + width;
+      var data = new Uint8Array(4 * texSize * texSize);
+
+      var step = 2.0 / width;
+
+      var pixel = new Array(4);
+
+      for (var yi = 0; yi < texSize; ++yi) {
+        for (var xi = 0; xi < texSize; ++xi) {
+          // The function is evaluated at the triangles' vertices.
+
+          // Compute desired position in clip space
+          var px = -1.0 + (xi * step);
+          var py = -1.0 + (yi * step);
+
+          evaluateAtClipCoords(px, py, pixel);
+          var index = 4 * (texSize * yi + xi);
+          data[index + 0] = pixel[0];
+          data[index + 1] = pixel[1];
+          data[index + 2] = pixel[2];
+          data[index + 3] = pixel[3];
+        }
+      }
+
+      gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, texSize, texSize, 0,
+                    gl.RGBA, gl.UNSIGNED_BYTE, data);
+    }
+
+    //----------------------------------------------------------------------
+    // Body of generateReferenceTexture
+    //
+
+    var texture = gl.createTexture();
+    gl.bindTexture(gl.TEXTURE_2D, texture);
+    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
+    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
+    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
+    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
+
+    if (isVertex) {
+      fillVertexReference();
+    } else {
+      fillFragmentReference();
+    }
+
+    return texture;
+  }
+};
+
+return {
+  /**
+   * runs a bunch of GLSL tests using the passed in parameters
+   * The parameters are:
+   *
+   * feature:
+   *    the name of the function being tested (eg, sin, dot,
+   *    normalize)
+   *
+   * testFunc:
+   *    The prototype of function to be tested not including the
+   *    return type.
+   *
+   * emuFunc:
+   *    A base function that can be used to generate emulation
+   *    functions. Example for 'ceil'
+   *
+   *      float $(func)_base(float value) {
+   *        float m = mod(value, 1.0);
+   *        return m != 0.0 ? (value + 1.0 - m) : value;
+   *      }
+   *
+   * args:
+   *    The arguments to the function
+   *
+   * baseArgs: (optional)
+   *    The arguments when a base function is used to create an
+   *    emulation function. For example 'float sign_base(float v)'
+   *    is used to implemenent vec2 sign_emu(vec2 v).
+   *
+   * simpleEmu:
+   *    if supplied, the code that can be used to generate all
+   *    functions for all types.
+   *
+   *    Example for 'normalize':
+   *
+   *        $(type) $(func)_emu($(args)) {
+   *           return value / length(value);
+   *        }
+   *
+   * gridRes: (optional)
+   *    The resolution of the mesh to generate. The default is a
+   *    1x1 grid but many vertex shaders need a higher resolution
+   *    otherwise the only values passed in are the 4 corners
+   *    which often have the same value.
+   *
+   * tests:
+   *    The code for each test. It is assumed the tests are for
+   *    float, vec2, vec3, vec4 in that order.
+   *
+   * tolerance: (optional)
+   *    Allow some tolerance in the comparisons. The tolerance is applied to 
+   *    both vertex and fragment shaders. The default tolerance is 0, meaning 
+   *    the values have to be identical.
+   *
+   * fragmentTolerance: (optional)
+   *    Specify a tolerance which only applies to fragment shaders. The 
+   *    fragment-only tolerance will override the shared tolerance for 
+   *    fragment shaders if both are specified. Fragment shaders usually
+   *    use mediump float precision so they sometimes require higher tolerance
+   *    than vertex shaders which use highp by default.
+   */
+  runFeatureTest: runFeatureTest,
+
+  /*
+   * Runs a bunch of GLSL tests using the passed in parameters
+   *
+   * The parameters are:
+   *
+   * tests:
+   *    Array of tests. For each test the following parameters are expected
+   *
+   *    name:
+   *       some description of the test
+   *    reference:
+   *       parameters for the reference shader (see below)
+   *    test:
+   *       parameters for the test shader (see below)
+   *
+   *    The parameter for the reference and test shaders are
+   *
+   *    shader: the GLSL for the shader
+   *    subs: any substitutions you wish to define for the shader.
+   *
+   *    Each shader is created from a basic template that
+   *    defines an input and an output. You can see the
+   *    templates at the top of this file. The input and output
+   *    change depending on whether or not we are generating
+   *    a vertex or fragment shader.
+   *
+   *    All this code function does is a bunch of string substitutions.
+   *    A substitution is defined by $(name). If name is found in
+   *    the 'subs' parameter it is replaced. 4 special names exist.
+   *
+   *    'input' the input to your GLSL. Always a vec4. All change
+   *    from 0 to 1 over the quad to be drawn.
+   *
+   *    'output' the output color. Also a vec4
+   *
+   *    'emu' a place to insert extra stuff
+   *    'extra' a place to insert extra stuff.
+   *
+   *    You can think of the templates like this
+   *
+   *       $(extra)
+   *       $(emu)
+   *
+   *       void main() {
+   *          // do math to calculate input
+   *          ...
+   *
+   *          $(shader)
+   *       }
+   *
+   *    Your shader first has any subs you provided applied as well
+   *    as 'input' and 'output'
+   *
+   *    It is then inserted into the template which is also provided
+   *    with your subs.
+   *
+   * gridRes: (optional)
+   *    The resolution of the mesh to generate. The default is a
+   *    1x1 grid but many vertex shaders need a higher resolution
+   *    otherwise the only values passed in are the 4 corners
+   *    which often have the same value.
+   *
+   * tolerance: (optional)
+   *    Allow some tolerance in the comparisons. The tolerance is applied to
+   *    both vertex and fragment shaders. The default tolerance is 0, meaning
+   *    the values have to be identical.
+   *
+   * fragmentTolerance: (optional)
+   *    Specify a tolerance which only applies to fragment shaders. The
+   *    fragment-only tolerance will override the shared tolerance for
+   *    fragment shaders if both are specified. Fragment shaders usually
+   *    use mediump float precision so they sometimes require higher tolerance
+   *    than vertex shaders which use highp.
+   */
+  runBasicTest: runBasicTest,
+
+  /**
+   * Runs a bunch of GLSL tests using the passed in parameters. The
+   * expected results are computed as a reference image in JavaScript
+   * instead of on the GPU. The parameters are:
+   *
+   * feature:
+   *    the name of the function being tested (eg, sin, dot,
+   *    normalize)
+   *
+   * testFunc:
+   *    The prototype of function to be tested not including the
+   *    return type.
+   *
+   * args:
+   *    The arguments to the function
+   *
+   * gridRes: (optional)
+   *    The resolution of the mesh to generate. The default is a
+   *    1x1 grid but many vertex shaders need a higher resolution
+   *    otherwise the only values passed in are the 4 corners
+   *    which often have the same value.
+   *
+   * tests:
+   *    Array of tests. It is assumed the tests are for float, vec2,
+   *    vec3, vec4 in that order. For each test the following
+   *    parameters are expected:
+   *
+   *       source: the GLSL source code for the tests
+   *
+   *       generator: a JavaScript function taking four parameters
+   *       which evaluates the same function as the GLSL source,
+   *       returning its result as a newly allocated array.
+   *
+   *       tolerance: (optional) a per-test tolerance.
+   *
+   * extra: (optional)
+   *    Extra GLSL code inserted at the top of each test's shader.
+   * 
+   * tolerance: (optional)
+   *    Allow some tolerance in the comparisons. The tolerance is applied to 
+   *    both vertex and fragment shaders. The default tolerance is 0, meaning 
+   *    the values have to be identical.
+   *
+   * fragmentTolerance: (optional)
+   *    Specify a tolerance which only applies to fragment shaders. The 
+   *    fragment-only tolerance will override the shared tolerance for 
+   *    fragment shaders if both are specified. Fragment shaders usually
+   *    use mediump float precision so they sometimes require higher tolerance
+   *    than vertex shaders which use highp.
+   */
+  runReferenceImageTest: runReferenceImageTest,
+
+  none: false
+};
+
+}());
+