| <!DOCTYPE html> |
| <html> |
| <head> |
| <style type="text/css" media="screen"> |
| body { |
| outline: 10px solid transparent; /* affects layer sizes */ |
| } |
| .canvas { |
| margin: 20px; |
| width: 200px; |
| height: 200px; |
| background-color: rgba(0, 0, 128, 0.0); |
| } |
| </style> |
| <script> |
| function initWebGL(canvasName, vshader, fshader, attribs, clearColor, clearDepth, premultAlpha) |
| { |
| var canvas = document.getElementById(canvasName); |
| var gl = canvas.getContext("experimental-webgl", {premultipliedAlpha: premultAlpha}); |
| if (!gl) { |
| alert("No WebGL context found"); |
| return null; |
| } |
| |
| gl.clearColor(clearColor[0], clearColor[1], clearColor[2], clearColor[3]); |
| gl.clearDepth(clearDepth); |
| |
| gl.enable(gl.DEPTH_TEST); |
| gl.enable(gl.BLEND); |
| gl.blendFunc(gl.SRC_ALPHA, gl.ONE); |
| |
| return gl; |
| } |
| |
| function drawCanvas(canvasID, premultAlpha) |
| { |
| var blueColor = 128.0 / 255.0 * (premultAlpha ? 0.5 : 1.0); |
| var gl = initWebGL(canvasID, "", "", [], [ 0, 0, blueColor, 0.5 ], 1, premultAlpha); |
| gl.viewport(0, 0, 200, 200); |
| gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); |
| } |
| |
| function init() |
| { |
| drawCanvas('canvas1', false); |
| drawCanvas('canvas2', true); |
| } |
| </script> |
| </head> |
| <body onload="init()"> |
| |
| <canvas class="canvas" id="canvas1" style="left: 20px" width="200" height="200"></canvas> |
| <canvas class="canvas" id="canvas2" style="left: 20px" width="200" height="200"></canvas> |
| |
| <!-- Both should look the same. --> |
| </body> |
| </html> |
