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<!DOCTYPE HTML>
<title>WebGL test: Hidden alpha on no-alpha contexts</title>
<script src='/tests/SimpleTest/SimpleTest.js'></script>
<link rel='stylesheet' href='/tests/SimpleTest/test.css'>
<script src='driver-info.js'></script>
<script src='webgl-util.js'></script>
<body>
<script id='vs' type='x-shader/x-vertex'>
attribute vec2 aPosCoord;
void main(void) {
gl_Position = vec4(aPosCoord, 0.0, 1.0);
}
</script>
<script id='fs' type='x-shader/x-fragment'>
precision mediump float;
void main(void) {
gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}
</script>
<canvas id='canvas' style='border: none;' width='100' height='100'></canvas>
<script>
var posCoords_arr = new Float32Array(2 * 4);
var posCoords_buff = null;
function DrawQuad(gl, prog, x0, y0, x1, y1) {
gl.useProgram(prog);
if (!posCoords_buff) {
posCoords_buff = gl.createBuffer();
}
gl.bindBuffer(gl.ARRAY_BUFFER, posCoords_buff);
posCoords_arr[0] = x0;
posCoords_arr[1] = y0;
posCoords_arr[2] = x1;
posCoords_arr[3] = y0;
posCoords_arr[4] = x0;
posCoords_arr[5] = y1;
posCoords_arr[6] = x1;
posCoords_arr[7] = y1;
gl.bufferData(gl.ARRAY_BUFFER, posCoords_arr, gl.STREAM_DRAW);
gl.enableVertexAttribArray(prog.aPosCoord);
gl.vertexAttribPointer(prog.aPosCoord, 2, gl.FLOAT, false, 0, 0);
gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
}
function DrawSquare(gl, prog, size) {
DrawQuad(gl, prog, -size, -size, size, size);
}
function Reset(gl) {
gl.canvas.width += 1;
gl.canvas.width -= 1;
}
function ReadCenterPixel(gl) {
var w = gl.drawingbufferWidth;
var h = gl.drawingbufferHeight;
var ret = new Uint8Array(4);
gl.readPixels(w/2, h/2, 1, 1, gl.RGBA, gl.UNSIGNED_BYTE, ret);
return ret;
}
function Test(gl, prog) {
gl.enable(gl.BLEND);
gl.blendFunc(gl.ZERO, gl.DST_ALPHA);
var iColor = 64;
var fColor = iColor / 255.0;
//////////////////
ok(true, 'clear(R,G,B,0)');
Reset(gl);
gl.clearColor(fColor, fColor, fColor, 0.0);
gl.clear(gl.COLOR_BUFFER_BIT);
var dataURL_pre = gl.canvas.toDataURL();
//console.log('Before blending: ' + dataURL_pre);
DrawSquare(gl, prog, 0.7);
var pixel = ReadCenterPixel(gl);
ok(pixel[0] == iColor &&
pixel[1] == iColor &&
pixel[2] == iColor, 'Color should be the same.');
ok(pixel[3] == 255, 'No-alpha should always readback as 1.0 alpha.');
var dataURL_post = gl.canvas.toDataURL();
//console.log('After blending: ' + dataURL_post);
ok(dataURL_post == dataURL_pre,
'toDataURL should be unchanged after blending.');
//////////////////
ok(true, 'mask(R,G,B,0), clear(R,G,B,1)');
Reset(gl);
gl.colorMask(true, true, true, false);
gl.clearColor(fColor, fColor, fColor, 1.0);
gl.clear(gl.COLOR_BUFFER_BIT);
gl.colorMask(true, true, true, true);
dataURL_pre = gl.canvas.toDataURL();
//console.log('Before blending: ' + dataURL_pre);
DrawSquare(gl, prog, 0.7);
var pixel = ReadCenterPixel(gl);
ok(pixel[0] == iColor &&
pixel[1] == iColor &&
pixel[2] == iColor, 'Color should be the same.');
ok(pixel[3] == 255, 'No-alpha should always readback as 1.0 alpha.');
ok(gl.getError() == 0, 'Should have no errors.');
dataURL_post = gl.canvas.toDataURL();
//console.log('After blending: ' + dataURL_post);
ok(dataURL_post == dataURL_pre,
'toDataURL should be unchanged after blending.');
ok(true, 'Test complete.');
SimpleTest.finish();
}
(function(){
var canvas = document.getElementById('canvas');
var attribs = {
alpha: false,
antialias: false,
premultipliedAlpha: false,
};
var gl = canvas.getContext('experimental-webgl', attribs);
ok(gl, 'WebGL should work.');
ok(gl.getParameter(gl.ALPHA_BITS) == 0, 'Shouldn\'t have alpha bits.');
var prog = WebGLUtil.createProgramByIds(gl, 'vs', 'fs');
ok(prog, 'Program should link.');
prog.aPosCoord = gl.getAttribLocation(prog, 'aPosCoord');
SimpleTest.waitForExplicitFinish();
SimpleTest.requestFlakyTimeout("untriaged");
setTimeout(function(){ Test(gl, prog); }, 500);
})();
</script>
</body>