| <!-- |
| 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. |
| --> |
| |
| <!-- author: Bill Baxter (wbaxter at google.com) --> |
| |
| <!DOCTYPE html> |
| <html> |
| <head> |
| <meta charset="utf-8"> |
| <title>Floored Division Accuracy Bug</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> |
| <script src="../../../js/glsl-conformance-test.js"></script> |
| </head> |
| |
| <body> |
| <div id="description"></div> |
| <div id="console"></div> |
| |
| <script id="shader-vs" type="x-shader/x-vertex"> |
| attribute vec4 vPosition; |
| uniform float divisor; |
| varying vec4 vColor; |
| void main(void) { |
| gl_Position = vPosition; |
| float index = 9.0; |
| // Floating point operations don't have any guaranteed precision, but they |
| // should at least be accurate to 1 part in 10^5. |
| float value = floor((index / divisor) * 1.00001); |
| vColor = (value == 3.) ? vec4(0, 1, 0, 1) : vec4(1, 0, 0, 1); |
| } |
| </script> |
| |
| <script id="shader-fs" type="x-shader/x-fragment"> |
| precision mediump float; |
| varying vec4 vColor; |
| void main(void) { |
| gl_FragColor = vColor; |
| } |
| </script> |
| <script> |
| "use strict"; |
| description(); |
| |
| debug(""); |
| // Reproduces bug seen on Mac OS X with AMD Radeon HD 6490 GPU |
| debug("If things are working correctly, then the square will be green."); |
| debug("If your card thinks floor(9. / 3.) is not 3 to within 1 part in 10^5, "); |
| debug("then the square will be red."); |
| |
| GLSLConformanceTester.runRenderTests([ |
| { |
| vShaderId: 'shader-vs', |
| vShaderSuccess: true, |
| fShaderId: 'shader-fs', |
| fShaderSuccess: true, |
| linkSuccess: true, |
| passMsg: 'Test that floor(9. / 3.) is 3 to within 1 part in 10^5', |
| uniforms: [{name: "divisor", functionName: "uniform1f", value: 3}] |
| } |
| ]); |
| |
| </script> |
| </body> |
| </html> |
