read-pixels-from-rgb8-into-pbo-bug.html

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Copyright (c) 2019 The Khronos Group Inc.

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<html>

<head>

<meta charset="utf-8">

<title>WebGL 2 Conformance Test: readPixels from RGB8 Buffer Into Pixel Pack Buffer.</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="example" width="4" height="4"></canvas>

<div id="description"></div>

<div id="console"></div>

<script>

"use strict";

debug("");

description("Verifies readPixels from RGB8 buffer into PIXEL_PACK buffer works");

debug("On MacOSX with AMD GPUs, the alpha channel is readback as 0 instead of 255");

var wtu = WebGLTestUtils;

var pixel = [0, 0, 0, 0];

var expectedColor = [255, 102, 0, 255];

var canvas = document.getElementById("example");

var gl = wtu.create3DContext(canvas, undefined, 2);

if (!gl) {

  testFailed("context does not exist");

} else {

  testPassed("context exists");

  var width = 4;

  var height = 4;

  var renderbuffer = gl.createRenderbuffer();

  gl.bindRenderbuffer(gl.RENDERBUFFER, renderbuffer);

  gl.renderbufferStorage(gl.RENDERBUFFER, gl.RGB8, width, height);

  var fbo = gl.createFramebuffer();

  gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);

  gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.RENDERBUFFER, renderbuffer);

  if (gl.checkFramebufferStatus(gl.FRAMEBUFFER) != gl.FRAMEBUFFER_COMPLETE) {

    testFailed("framebuffer with RGB8 color buffer is incomplete");

  } else {

    gl.clearColor(1.0, 0.0, 0.0, 1.0);

    gl.clear(gl.COLOR_BUFFER_BIT);

    var pbo = gl.createBuffer();

    gl.bindBuffer(gl.PIXEL_PACK_BUFFER, pbo);

    gl.bufferData(gl.PIXEL_PACK_BUFFER, width * height * 4, gl.STATIC_COPY);

    gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, 0);

    var data = new Uint8Array(width * height * 4);

    gl.getBufferSubData(gl.PIXEL_PACK_BUFFER, 0, data);

    for (var ii = 0; ii < width * height; ++ii) {

      if (data[ii * 4] != 255 ||

          data[ii * 4 + 1] != 0 ||

          data[ii * 4 + 2] != 0 ||

          data[ii * 4 + 3] != 255) {

        testFailed("Expected in pixel " + ii + ": [255,0,0,255], got: " +

                   [data[ii * 4], data[ii * 4 + 1], data[ii * 4 + 2], data[ii * 4 + 3]]);

        break;

  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "Tests should complete without gl errors");

debug("");

var successfullyParsed = true;

</script>

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