| <!-- |
| 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>Draw WebGL to Canvas2D Repeatedly</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> |
| "use strict"; |
| const wtu = WebGLTestUtils; |
| |
| const sz = 256; |
| |
| function drawTo2DCanvas(c2, webGLCanvas) { |
| // Always clear 2D canvas to solid green first. |
| c2.clearRect(0, 0, sz, sz); |
| c2.fillStyle = 'rgb(0,255,0)'; |
| c2.fillRect(0, 0, sz, sz); |
| // Draw WebGL canvas to this canvas. |
| c2.drawImage(webGLCanvas, 0, 0); |
| } |
| |
| function runTest() { |
| description(); |
| debug('Repeatedly drawing a WebGL canvas to a 2D canvas should only draw the most recently rendered WebGL content.'); |
| debug('Regression test for <a href="http://crbug.com/894021">http://crbug.com/894021</a>'); |
| |
| let c2 = document.getElementById('canvas-2d').getContext('2d'); |
| let webGLCanvas = document.getElementById('canvas-webgl'); |
| let gl = wtu.create3DContext(webGLCanvas, { alpha: true, antialias: false, premultipliedAlpha: true }); |
| let tolerance = 2; |
| |
| // Clear left half of WebGL canvas to red and right half to |
| // transparent black. |
| gl.disable(gl.SCISSOR_TEST); |
| gl.clearColor(0.0, 0.0, 0.0, 0.0); |
| gl.clear(gl.COLOR_BUFFER_BIT); |
| gl.scissor(0, 0, sz / 2, sz); |
| gl.enable(gl.SCISSOR_TEST); |
| gl.clearColor(1.0, 0.0, 0.0, 1.0); |
| gl.clear(gl.COLOR_BUFFER_BIT); |
| // Draw to 2D canvas. |
| drawTo2DCanvas(c2, webGLCanvas); |
| |
| // Clear right half of WebGL canvas to red and left half to |
| // transparent black. |
| gl.disable(gl.SCISSOR_TEST); |
| gl.clearColor(0.0, 0.0, 0.0, 0.0); |
| gl.clear(gl.COLOR_BUFFER_BIT); |
| gl.scissor(sz / 2, 0, sz / 2, sz); |
| gl.enable(gl.SCISSOR_TEST); |
| gl.clearColor(1.0, 0.0, 0.0, 1.0); |
| gl.clear(gl.COLOR_BUFFER_BIT); |
| // Draw to 2D canvas. |
| drawTo2DCanvas(c2, webGLCanvas); |
| |
| // Clear WebGL canvas to transparent black. |
| gl.disable(gl.SCISSOR_TEST); |
| gl.clearColor(0.0, 0.0, 0.0, 0.0); |
| gl.clear(gl.COLOR_BUFFER_BIT); |
| // Draw to 2D canvas. |
| drawTo2DCanvas(c2, webGLCanvas); |
| |
| // 2D canvas should be green. |
| // In the error case, the rendering results from earlier draws were |
| // being accumulated, so the 2D canvas was ultimately red. |
| wtu.checkCanvasRect(c2, 0, 0, sz, sz, |
| [ 0, 255, 0, 255 ], |
| "should be green", |
| tolerance); |
| |
| finishTest(); |
| } |
| |
| requestAnimationFrame(runTest); |
| </script> |
| </head> |
| <body> |
| <div id="description"></div> |
| <div id="console"></div> |
| <canvas id="canvas-webgl" width="256" height="256"></canvas> |
| <canvas id="canvas-2d" width="256" height="256"></canvas> |
| </body> |
| </html> |