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<html>
<head>
<script src="../../../resources/js-test.js"></script>
<script src="resources/webgl-test.js"></script>
<script>
function runTest(gl, width, height)
{
debug('Test whether the WebGL internal buffers have been initialized to 0.');
var totalBytes = width * height * 4;
var buf = new Uint8Array(totalBytes);
gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, buf);
if (gl.getError() != gl.NO_ERROR) {
testFailed('GL error detected after readPixels().');
return false;
}
for (var i = 0; i < totalBytes; ++i) {
if (buf[i] != 0) {
testFailed('WebGL internal buffers are dirty.');
return false;
}
}
testPassed('Buffers have been initialized to 0.');
debug('Test whether user created buffers have been initialized to 0.');
var fbo = gl.createFramebuffer();
gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
var colorbuffer = gl.createRenderbuffer();
gl.bindRenderbuffer(gl.RENDERBUFFER, colorbuffer);
gl.renderbufferStorage(gl.RENDERBUFFER, gl.RGBA4, width, height);
if (gl.getError() != gl.NO_ERROR) {
testFailed('GL error detected after renderbufferStorage(internalformat = RGBA4).');
return false;
}
gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.RENDERBUFFER, colorbuffer);
if (gl.checkFramebufferStatus(gl.FRAMEBUFFER) != gl.FRAMEBUFFER_COMPLETE) {
testFailed('Framebuffer incomplete.');
return false;
}
gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, buf);
if (gl.getError() != gl.NO_ERROR) {
testFailed('GL error detected after readPixels().');
return false;
}
for (var i = 0; i < totalBytes; ++i) {
if (buf[i] != 0) {
testFailed('User created buffers are dirty.');
return false;
}
}
testPassed('Buffers have been initialized to 0.');
return true;
}
</script>
</head>
<body>
<canvas id="testbed" width="400px" height="400px"></canvas>
<div id="description"></div>
<div id="console"></div>
<script>
description('Verify renderbuffers are initialized to 0 before being read in WebGL');
var canvas = document.getElementById("testbed");
var gl = canvas.getContext("webgl");
if (gl) {
runTest(gl, canvas.width, canvas.height);
// Testing that canvas resizing will clear the buffers with 0 instead of the current clear values.
gl.clearColor(1, 0, 0, 1);
canvas.width += 1;
canvas.height += 1;
runTest(gl, canvas.width, canvas.height);
// Testing buffer clearing won't change the clear values.
var clearColor = gl.getParameter(gl.COLOR_CLEAR_VALUE);
shouldBe("clearColor", "[1, 0, 0, 1]");
} else
testFailed('canvas.getContext() failed');
</script>
</body>
</html>
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