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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.
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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<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>
</head>
<body>
<canvas id="testbed" width="40" height="40" style="width: 40px; height: 40px;"></canvas>
<div id="description"></div>
<div id="console"></div>
<script>
"use strict";
var wtu = WebGLTestUtils;
description('Verify multisampled renderbuffers are initialized to 0 before being read in WebGL');

var gl = wtu.create3DContext("testbed", null, 2);

if (!gl) {
    testFailed('canvas.getContext() failed');
} else {
    // Set the clear color to green. It should never show up.
    gl.clearColor(0, 1, 0, 1);

    let c = gl.canvas;
    var maxSamples = gl.getInternalformatParameter(
        gl.RENDERBUFFER, gl.RGBA8, gl.SAMPLES)[0];
    for (let i = 0; i < 2; ++i) {
        runTest(gl, {alloc1: {w: c.width, h: c.height, s: maxSamples}, alloc2: null});
        runTest(gl, {alloc1: null, alloc2: {w: c.width, h: c.height, s: maxSamples}});

        // Tests for initially allocating at the wrong size.
        // This is caused by a Qualcomm driver bug: http://crbug.com/696126
        runTest(gl, {alloc1: {w: 5, h: 5, s: maxSamples}, alloc2: {w: c.width, h: c.height, s: maxSamples}});
        runTest(gl, {alloc1: {w: 5, h: 5, s: maxSamples}, alloc2: {w: c.width, h: c.height, s: 0}});
        runTest(gl, {alloc1: {w: 5, h: 5, s: 0}, alloc2: {w: c.width, h: c.height, s: maxSamples}});
    }

    // Testing buffer clearing won't change the clear values.
    var clearColor = gl.getParameter(gl.COLOR_CLEAR_VALUE);
    shouldBe("clearColor", "[0, 1, 0, 1]");
    wtu.glErrorShouldBe(gl, gl.NO_ERROR, 'should be no errors');
}

function runTest(gl, params) {
    debug("Test for color buffer: " + JSON.stringify(params));
    let resolve = params.alloc2 ? params.alloc2 : params.alloc1;
    wtu.checkCanvasRect(gl, 0, 0, resolve.w, resolve.h,
                        [0, 0, 0, 0],
                        "internal buffers have been initialized to 0");

    // fill the back buffer so we know that reading below happens from
    // the renderbuffer.
    gl.clear(gl.COLOR_BUFFER_BIT);

    // Set up non-multisampled buffer to blit to and read back from.
    var fbo = gl.createFramebuffer();
    gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
    var buffer = gl.createRenderbuffer();
    gl.bindRenderbuffer(gl.RENDERBUFFER, buffer);
    gl.renderbufferStorage(gl.RENDERBUFFER, gl.RGBA8, resolve.w, resolve.h);
    attachBuffer(buffer);
    shouldBe("gl.checkFramebufferStatus(gl.FRAMEBUFFER)",
             "gl.FRAMEBUFFER_COMPLETE");
    wtu.glErrorShouldBe(gl, gl.NO_ERROR, 'should be no errors');
    gl.clear(gl.COLOR_BUFFER_BIT);
    wtu.checkCanvasRect(gl, 0, 0, resolve.w, resolve.h,
                        [0, 255, 0, 255],
                        "user buffer has been cleared to green");

    // Set up multisampled buffer to test.
    var fbo_m = gl.createFramebuffer();
    gl.bindFramebuffer(gl.FRAMEBUFFER, fbo_m);
    var buffer_m = gl.createRenderbuffer();
    gl.bindRenderbuffer(gl.RENDERBUFFER, buffer_m);

    if (params.alloc1) {
        allocStorage(params.alloc1.w, params.alloc1.h, params.alloc1.s);
    }
    attachBuffer(buffer_m);
    if (params.alloc2) {
        if (params.alloc1) {
            // Clear the FBO in order to make sure framebufferRenderbuffer is
            // committed. (In Firefox, framebufferRenderbuffer is deferred, so
            // this is needed to trigger the bug.)
            gl.clear(gl.COLOR_BUFFER_BIT);
        }
        allocStorage(params.alloc2.w, params.alloc2.h, params.alloc2.s);
    }

    function allocStorage(width, height, samples) {
        gl.renderbufferStorageMultisample(
            gl.RENDERBUFFER, samples, gl.RGBA8, width, height);
        wtu.glErrorShouldBe(gl, gl.NO_ERROR,
            "should be no error after renderbufferStorageMultisample(RGBA8).");
    }

    function attachBuffer(buffer) {
        gl.framebufferRenderbuffer(
            gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.RENDERBUFFER, buffer);
        wtu.glErrorShouldBe(gl, gl.NO_ERROR,
            "should be no error after framebufferRenderbuffer.");
    }

    shouldBe("gl.checkFramebufferStatus(gl.FRAMEBUFFER)",
             "gl.FRAMEBUFFER_COMPLETE");
    wtu.glErrorShouldBe(gl, gl.NO_ERROR, 'should be no errors');

    // Blit from multisampled buffer to non-multisampled buffer.
    gl.bindFramebuffer(gl.READ_FRAMEBUFFER, fbo_m);
    gl.bindFramebuffer(gl.DRAW_FRAMEBUFFER, fbo);
    // Blit color from fbo_m (should be black) to fbo (should be green)
    gl.blitFramebuffer(0, 0, resolve.w, resolve.h,
                       0, 0, resolve.w, resolve.h,
                       gl.COLOR_BUFFER_BIT, gl.NEAREST);
    wtu.glErrorShouldBe(gl, gl.NO_ERROR, 'should be no errors');

    gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
    wtu.checkCanvasRect(gl, 0, 0, resolve.w, resolve.h,
                        [0, 0, 0, 0],
                        "user buffer has been initialized to 0");

    gl.deleteFramebuffer(fbo_m);
    gl.deleteRenderbuffer(buffer_m);
    gl.deleteFramebuffer(fbo);
    gl.deleteRenderbuffer(buffer);

    // this clear should not matter we are about to resize
    gl.clear(gl.COLOR_BUFFER_BIT);

    gl.canvas.width += 1;
    gl.canvas.height += 1;

    wtu.glErrorShouldBe(gl, gl.NO_ERROR, 'should be no errors');
    debug('');
}

var successfullyParsed = true;
</script>
<script src="../../js/js-test-post.js"></script>
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