1 files changed, 185 insertions, 0 deletions
diff --git a/dom/canvas/test/webgl-conf/checkout/conformance/glsl/variables/gl-fragcoord-xy-values.html b/dom/canvas/test/webgl-conf/checkout/conformance/glsl/variables/gl-fragcoord-xy-values.html
new file mode 100644
index 0000000000..161a58bfc6
--- /dev/null
+++ b/dom/canvas/test/webgl-conf/checkout/conformance/glsl/variables/gl-fragcoord-xy-values.html
@@ -0,0 +1,185 @@
+<!--
+Copyright (c) 2019 The Khronos Group Inc.
+Use of this source code is governed by an MIT-style license that can be
+found in the LICENSE.txt file.
+-->
+
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+<title>gl-fragcoord Test</title>
+<link rel="stylesheet" href="../../../resources/js-test-style.css"/>
+<script src="../../../js/js-test-pre.js"></script>
+<script src="../../../js/webgl-test-utils.js"> </script>
+</head>
+<body>
+<canvas id="canvas" width="32" height="32">
+</canvas>
+<div id="description"></div>
+<div id="console"></div>
+<script id="vshader" type="x-shader/x-vertex">
+// Inputs
+attribute vec4 aPosInfo;
+
+// Outputs
+varying vec2 vTargetPixelCoord;
+
+void main()
+{
+  vTargetPixelCoord = aPosInfo.zw;
+
+  gl_PointSize = 1.0;
+  gl_Position  = vec4(aPosInfo.xy, 0.0, 1.0);
+}
+</script>
+
+<script id="fshader" type="x-shader/x-fragment">
+precision mediump float;
+
+// Inputs
+varying vec2 vTargetPixelCoord;
+
+// Colors used to signal correctness
+const vec4 red   = vec4(1.0, 0.0, 0.0, 1.0);
+const vec4 green = vec4(0.0, 1.0, 0.0, 1.0);
+
+void main()
+{
+  // Check pixel index
+  bool pixelIxValid = (floor(gl_FragCoord.xy) == vTargetPixelCoord);
+
+  // Check fractional part of coordinates
+  bool fracCoordValid = all(lessThan(abs(fract(gl_FragCoord.xy) - vec2(0.5)), vec2(0.0001)));
+
+  gl_FragColor = (pixelIxValid && fracCoordValid) ? green : red;
+}
+</script>
+
+<script id="test_fshader" type="x-shader/x-fragment">
+// Shader to test if the frame buffer positions within the output pixel are different for the five render passes
+// Pass on frame buffer position in varying, change in vertex shader : vTargetPixelCoord = aPosInfo.xy;
+// Set test_fshader in setupProgram()
+
+precision mediump float;
+
+// Inputs
+varying vec2 vTargetPixelCoord;
+
+const vec2 pixSize = vec2(2.0/32.0, 2.0/32.0);
+
+void main()
+{
+  // Coordinates within a framebuffer pixel [0, 1>
+  vec2 inPixelCoord = fract(vTargetPixelCoord / pixSize);
+
+  // Create different color dependent on the position inside the framebuffer pixel
+  float r = (inPixelCoord.x < 0.4) ? 0.2 : (inPixelCoord.x > 0.6) ? 0.8 : 0.5;
+  float g = (inPixelCoord.y < 0.4) ? 0.2 : (inPixelCoord.y > 0.6) ? 0.8 : 0.5;
+
+  gl_FragColor = vec4(r, g, 0.0, 1.0);
+}
+</script>
+
+<script>
+"use strict";
+
+// Test if gl_FragCoord.xy values are always of the form :
+// (first framebuffer pixel index + 0.5, second framebuffer pixel index + 0.5)
+// (if no multisampling)
+
+// This is done by rendering a set of points which targets either the center of the
+// output pixel or the center of one of the quadrants
+
+// Constants
+var floatsPerAttribute = 4;
+
+// Globals
+var wtu;
+var gl;
+var program;
+var vxBuffer;
+
+// Set data for one attribute (framebuffer.xy, pixel_index.xy)
+function setPixelData(data, dIx, xx, yy, xSize, ySize, xOffset, yOffset)
+{
+  // Frame buffer first coordinate [-1, 1]
+  data[dIx++] = (xx + 0.5) * xSize + xOffset - 1;
+
+  // Frame buffer second coordinate [-1, 1]
+  data[dIx++] = (yy + 0.5) * ySize + yOffset - 1;
+
+  // Frame buffer pixel first index
+  data[dIx++] = xx;
+
+  // Frame buffer pixel second index
+  data[dIx++] = yy;
+
+  return dIx;
+}
+
+// Create attribute data
+function createAttributeData(xOffset, yOffset)
+{
+  // Retrieve realised dimensions of viewport
+  var widthPx    = gl.drawingBufferWidth;
+  var heightPx   = gl.drawingBufferHeight;
+  var pixelCount = widthPx * heightPx;
+
+  // Pixel size in framebuffer coordinates
+  var pWidth  = 2 / widthPx;
+  var pHeight = 2 / heightPx;
+  var data = new Float32Array(pixelCount * floatsPerAttribute);
+  var dIx = 0;
+  for (var yy = 0; yy < heightPx; ++yy)
+    for (var xx = 0; xx < widthPx; ++xx)
+      dIx = setPixelData(data, dIx, xx, yy, pWidth, pHeight,  xOffset * pWidth,  yOffset * pHeight);
+
+  if (dIx !== data.length)
+    wtu.error("gl-fragcoord-xy-values.html, createAttributeData(), index not correct at end");
+
+  return data;
+}
+
+// Initialize test
+function init()
+{
+  description("tests gl_FragCoord.xy values");
+
+  wtu = WebGLTestUtils;
+  gl = wtu.create3DContext("canvas", { antialias: false });
+  program = wtu.setupProgram(gl, ["vshader", "fshader"], ["aPosInfo"]);
+  vxBuffer = gl.createBuffer();
+
+  gl.bindBuffer(gl.ARRAY_BUFFER, vxBuffer);
+  gl.enableVertexAttribArray(0);
+  gl.vertexAttribPointer(0, floatsPerAttribute, gl.FLOAT, false, 0, 0);
+}
+
+// Render data
+function render(xOffset, yOffset, passMsg)
+{
+  // Set attribute data
+  var data = createAttributeData(xOffset, yOffset);
+  gl.bufferData(gl.ARRAY_BUFFER, data, gl.DYNAMIC_DRAW);
+
+  gl.clear(gl.COLOR_BUFFER_BIT);
+  gl.drawArrays(gl.POINTS, 0, data.length / floatsPerAttribute);
+  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "no errors from draw");
+  var green = [0, 255, 0, 255];
+  wtu.checkCanvas(gl, green, passMsg);
+}
+
+// Run tests
+init();
+render(0, 0, "green : sampling at center of output pixel is correct");
+render(0.25, 0.25, "green : sampling in top right quadrant of output pixel is correct");
+render(-0.25, 0.25, "green : sampling in top left quadrant of output pixel is correct");
+render( 0.25, -0.25, "green : sampling in bottom right quadrant of output pixel is correct");
+render(-0.25, -0.25, "green : sampling in bottom left quadrant of output pixel is correct");
+var successfullyParsed = true;
+</script>
+<script src="../../../js/js-test-post.js"></script>
+
+</body>
+</html>