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context-no-alpha-fbo-with-alpha.html (2490B)

      1 <!--
      2 Copyright (c) 2019 The Khronos Group Inc.
      3 Use of this source code is governed by an MIT-style license that can be
      4 found in the LICENSE.txt file.
      5 -->
      6 
      7 <!DOCTYPE html>
      8 <html>
      9 <head>
     10 <meta charset="utf-8">
     11 <link rel="stylesheet" href="../../resources/js-test-style.css"/>
     12 <script src="../../js/js-test-pre.js"></script>
     13 <script src="../../js/webgl-test-utils.js"></script>
     14 
     15 <script>
     16 "use strict";
     17 
     18 var wtu = WebGLTestUtils;
     19 
     20 // This declaration needs to be global for "shouldBe" to see it
     21 var gl;
     22 
     23 function init()
     24 {
     25    description('Verify that a WebGL context with alpha:false still works correctly after handling textures with an alpha channel.');
     26 
     27    runTest();
     28 }
     29 
     30 function getWebGL(contextAttribs)
     31 {
     32    return wtu.create3DContext("c", contextAttribs);
     33 }
     34 
     35 function runTest()
     36 {
     37    var buf = new Uint8Array(1 * 1 * 4);
     38    shouldBeNonNull("gl = getWebGL({ alpha: false, antialias: false })");
     39 
     40    // Clear to black. Alpha channel of clearColor() is ignored.
     41    gl.clearColor(0.0, 0.0, 0.0, 0.7);
     42    gl.clear(gl.COLOR_BUFFER_BIT);
     43    wtu.checkCanvasRect(gl, 0, 0, 1, 1, [0, 0, 0, 255],
     44                        "Alpha channel of clearColor should be ignored");
     45 
     46    wtu.waitForComposite(function() {
     47        // Make a new framebuffer and attach a texture with an alpha channel.
     48        var fbo = gl.createFramebuffer();
     49        gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
     50        var texture = gl.createTexture();
     51        gl.bindTexture(gl.TEXTURE_2D, texture);
     52        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, 1, 1, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);
     53        gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, 0);
     54 
     55        // Clear texture. Note that alpha channel is not 1.0.
     56        gl.clearColor(1.0, 0.0, 0.0, 0.5);
     57        gl.clear(gl.COLOR_BUFFER_BIT);
     58        wtu.checkCanvasRect(gl, 0, 0, 1, 1, [255, 0, 0, 128],
     59                            "Alpha channel of clearColor should be obeyed for FBO with alpha channel",
     60                            1);
     61 
     62        // Bind back buffer and check that its alpha channel is still 1.0.
     63        gl.bindFramebuffer(gl.FRAMEBUFFER, null);
     64        wtu.checkCanvasRect(gl, 0, 0, 1, 1, [0, 0, 0, 255],
     65                            "Alpha channel of back buffer should still be 255");
     66        finishTest();
     67    });
     68 }
     69 
     70 </script>
     71 </head>
     72 <body onload="init()">
     73 <div id="description"></div>
     74 <div id="console"></div>
     75 <canvas width="20" height="20" style="border: 1px solid blue;" id="c"></canvas>
     76 </body>
     77 </html>