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| |
| <!DOCTYPE html> |
| <html> |
| <head> |
| <meta charset="utf-8"> |
| <title>WebGL multisampling fragment shader evaluation</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 id="vshader" type="x-shader/x-vertex">#version 300 es |
| layout(location=0) in vec4 aPosition; |
| out vec4 vPosition; |
| void main() |
| { |
| gl_Position = vec4(aPosition); |
| vPosition = aPosition; |
| } |
| </script> |
| <script id="fshader" type="x-shader/x-fragment">#version 300 es |
| precision highp float; |
| in vec4 vPosition; |
| layout(location=0) out vec4 oColor; |
| void main() |
| { |
| if (vPosition.x < 0.0) { |
| oColor = vec4(1, 0, 0, 1); |
| } else if (vPosition.y < 0.0) { |
| oColor = vec4(0, 1, 0, 1); |
| } else { |
| oColor = vec4(0, 0, 1, 1); |
| } |
| } |
| </script> |
| |
| </head> |
| <body> |
| <div id="description"></div> |
| <div id="console"></div> |
| |
| <script> |
| "use strict"; |
| |
| var wtu = WebGLTestUtils; |
| description("Verify that fragment shader is evaluated only once per framebuffer pixel when multisampling is used."); |
| |
| // GLES 3.0.5 section 3.6.3. Polygon Multisample Rasterization: |
| // "Polygon rasterization produces a fragment for each framebuffer pixel with one or more sample points that satisfy |
| // the point sampling criteria described in section 3.6.1." |
| |
| debug("Regression test for <a href='http://crbug.com/682815'>http://crbug.com/682815</a>"); |
| |
| function runTest(testParams) { |
| let canvas = document.createElement('canvas'); |
| canvas.width = 1; |
| canvas.height = 1; |
| let gl = wtu.create3DContext(canvas, {antialias: false}, 2); |
| |
| // Find the supported samples for a multisampled renderbuffer of the appropriate internal format. |
| let samples = gl.getInternalformatParameter(gl.RENDERBUFFER, gl[testParams.internalformat], gl.SAMPLES); |
| if (!samples || !samples.length) { |
| testFailed("Could not query supported sample counts for required multisampling format " + testParams.internalformat); |
| return; |
| } |
| |
| // Note that supported sample counts are required to be reported in descending order. |
| debug('Testing with sample count ' + samples[0]); |
| // Create a framebuffer with a multisampled renderbuffer with the maximum supported number of samples. |
| let rb = gl.createRenderbuffer(); |
| gl.bindRenderbuffer(gl.RENDERBUFFER, rb); |
| gl.renderbufferStorageMultisample(gl.RENDERBUFFER, samples[0], gl[testParams.internalformat], 1, 1); |
| let fb = gl.createFramebuffer(); |
| gl.bindFramebuffer(gl.FRAMEBUFFER, fb); |
| gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.RENDERBUFFER, rb); |
| if (gl.checkFramebufferStatus(gl.FRAMEBUFFER) != gl.FRAMEBUFFER_COMPLETE) { |
| testFailed("Rendering to a multisampled renderbuffer of format " + testParams.internalformat + " is required."); |
| return; |
| } |
| |
| // Create a program that will choose between one of different possible colors in the fragment shader. |
| // It should be evaluated only once per framebuffer pixel, so only one of the colors will end up in the framebuffer. |
| // However, if the multisampling mode is incorrectly implemented by supersampling, the samples may have different |
| // colors. |
| let program = wtu.setupProgram(gl, ["vshader", "fshader"], ["aPosition"]); |
| |
| // Render one triangle using the program. The triangle needs to extend far outside the viewport on all sides, so |
| // that we can safely assume all samples fall inside the triangle. GLES 3.0.5: |
| // "The sample points associated with a pixel may be located inside or outside of the unit square that is considered to bound the pixel." |
| // Here we assume that sample points are less than 9999 pixels away from the pixel they are associated with. |
| let buffer = gl.createBuffer(); |
| gl.bindBuffer(gl.ARRAY_BUFFER, buffer); |
| gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([ 10000, 30000, |
| -30000, -10000, |
| 10000, -10000]), gl.STATIC_DRAW); |
| gl.enableVertexAttribArray(0); |
| gl.vertexAttribPointer(0, 2, gl.FLOAT, false, 0, 0); |
| gl.drawArrays(gl.TRIANGLES, 0, 3); |
| |
| gl.bindFramebuffer(gl.DRAW_FRAMEBUFFER, null); |
| gl.blitFramebuffer(0, 0, 1, 1, 0, 0, 1, 1, gl.COLOR_BUFFER_BIT, gl.NEAREST); |
| gl.bindFramebuffer(gl.READ_FRAMEBUFFER, null); |
| |
| let readBuffer = new Uint8Array(4); |
| gl.readPixels(0, 0, 1, 1, gl.RGBA, gl.UNSIGNED_BYTE, readBuffer); |
| |
| // Check that the canvas is one of the colors that the fragment shader may generate, and not a blend of them. |
| let possibleColors = [ |
| [255, 0, 0, 255], |
| [0, 255, 0, 255], |
| [0, 0, 255, 255] |
| ]; |
| let anyColorMatched = false; |
| for (let i = 0; i < possibleColors.length; ++i) { |
| let colorMatched = true; |
| for (let j = 0; j < 4; ++j) { |
| if (Math.abs(readBuffer[j] - possibleColors[i][j]) > 2) { |
| colorMatched = false; |
| } |
| } |
| if (colorMatched) { |
| anyColorMatched = true; |
| } |
| } |
| if (!anyColorMatched) { |
| testFailed("Color in framebuffer was not one of the colors generated by the fragment shader: " + readBuffer); |
| } else { |
| testPassed("Color in framebuffer was one of the colors generated by the fragment shader: " + readBuffer); |
| } |
| } |
| |
| runTest({internalformat: 'RGBA8'}); |
| |
| var successfullyParsed = true; |
| </script> |
| <script src="../../js/js-test-post.js"></script> |
| |
| </body> |
| </html> |