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<!--
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>Conditional discard in loop issue</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="output" style="border: none;" width="256" height="256"></canvas>
<div id="description"></div>
<div id="console"></div>
<script id="shader-vs" type="x-shader/x-vertex">
// Inputs
attribute vec4 a_position;
attribute vec2 a_tex_coords;
// Output
varying vec2 v_tex_coords;
void main(void) {
v_tex_coords = a_tex_coords;
gl_Position = a_position;
}
</script>
<script id="shader-fs" type="x-shader/x-fragment">
precision mediump float;
// Constants
const float TEXEL_COUNT_V = 256.0;
const float TEXEL_HEIGHT = 1.0 / TEXEL_COUNT_V;
const float SEP_IX = TEXEL_COUNT_V / 2.0;
const vec4 GREEN = vec4(0.0, 1.0, 0.0, 1.0);
const vec4 BLUE = vec4(0.0, 0.0, 1.0, 1.0);
// Input
varying vec2 v_tex_coords;
uniform sampler2D u_data;
// Without this function or directly returning the data, the issue does not occur
mediump vec4 UnpackData(in vec4 inData) {
float s = inData.x;
// Note s is always 0
// mod(0, 1) = 0
// So return value = (0, 0, -1, 0)
return vec4(0.0, 0.0, mod(s, 1.0) - 1.0, 0.0);
// Comment out the line above and uncomment the line below and the test succeeds on angle-dx11
// return vec4(0.0, 0.0, -1.0, 0.0);
}
void main(void) {
// Set initial color
gl_FragColor = BLUE;
if (gl_FragCoord.y <= SEP_IX) {
mediump vec2 addr = vec2(v_tex_coords.x, TEXEL_HEIGHT);
for (float e_ix = 0.0; e_ix < TEXEL_COUNT_V; ++e_ix) {
vec4 entry = texture2D(u_data, addr);
mediump vec4 unpack = UnpackData(entry);
// Buffer is filled with 0, unpack is always (0, 0, -1, 0)
// So discard is always triggered
if (unpack.z == -1.0) {
discard;
}
addr.y += unpack.z * TEXEL_HEIGHT;
}
// If discard is not triggered the output color is blue
}
else {
gl_FragColor = GREEN;
}
}
</script>
<script>
"use strict";
description();
debug("");
debug("If the code is executed correctly, the upper half of the viewport will be green, the lower half will be red.");
debug("This is a conformance suite test for the issue reported here : https://code.google.com/p/angleproject/issues/detail?id=706");
var wtu = WebGLTestUtils;
var canvas = document.getElementById("output");
var gl = wtu.create3DContext(canvas);
if (!gl) {
testFailed("context does not exist");
} else {
// Create texture filled with zero's
var tex = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, tex);
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);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
wtu.fillTexture(gl, tex, 256, 256, [0, 0, 0, 0]);
// Clear complete viewport to red
gl.clearColor(1.0, 0.0, 0.0, 1.0);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
var attribBuffers = wtu.setupUnitQuad(gl, 0, 1);
var program = wtu.setupProgram(gl, ["shader-vs", "shader-fs"], ["a_position", "a_tex_coords"], [0, 1], true);
// Bind texture
var uniformMap = wtu.getUniformMap(gl, program);
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, tex);
gl.uniform1i(uniformMap.u_data.location, 0);
// Draw
wtu.drawUnitQuad(gl);
// Verify output
wtu.checkCanvasRect(gl, 0, 0, 256, 128, [ 255, 0, 0, 255 ], "should be red", 1);
wtu.checkCanvasRect(gl, 0, 128, 256, 128, [ 0, 255, 0, 255 ], "should be green", 1);
}
var successfullyParsed = true;
</script>
<script src="../../../js/js-test-post.js"></script>
</body>
</html>