<!--
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">
<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 stencil renderbuffers are initialized to 0 before being read in WebGL');

var gl = wtu.create3DContext("testbed");

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

    let c = gl.canvas;
    for (let i = 0; i < 2; ++i) {
        runTest(gl, {alloc1: {w: c.width, h: c.height}, alloc2: null});
        runTest(gl, {alloc1: null, alloc2: {w: c.width, h: c.height}});
        // Tests for initially allocating at the wrong size.
        runTest(gl, {alloc1: {w: 5, h: 5}, alloc2: {w: c.width, h: c.height}});
    }

    // 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 stencil buffer: " + JSON.stringify(params));
    let final = params.alloc2 ? params.alloc2 : params.alloc1;
    gl.viewport(0, 0, final.w, final.h);
    wtu.checkCanvasRect(gl, 0, 0, final.w, final.h,
                        [0, 0, 0, 0],
                        "internal buffers have been initialized to 0");

    gl.disable(gl.STENCIL_TEST);

    // fill the back buffer so we know that reading below happens from
    // the renderbuffer.
    gl.clearStencil(2);
    gl.clear(gl.COLOR_BUFFER_BIT | gl.STENCIL_BUFFER_BIT);

    // Set up (color+stencil) test buffer.
    var fbo = gl.createFramebuffer();
    gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
    var buffer = gl.createRenderbuffer();
    var stencilBuffer = gl.createRenderbuffer();

    if (params.alloc1) {
        gl.bindRenderbuffer(gl.RENDERBUFFER, buffer);
        allocStorage(gl.RGBA4, params.alloc1.w, params.alloc1.h);
        gl.bindRenderbuffer(gl.RENDERBUFFER, stencilBuffer);
        allocStorage(gl.STENCIL_INDEX8, params.alloc1.w, params.alloc1.h);
    }
    gl.bindRenderbuffer(gl.RENDERBUFFER, buffer);
    gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.RENDERBUFFER, buffer);
    gl.bindRenderbuffer(gl.RENDERBUFFER, stencilBuffer);
    gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.STENCIL_ATTACHMENT, gl.RENDERBUFFER, stencilBuffer);
    if (params.alloc2) {
        if (params.alloc1) {
            if (gl.checkFramebufferStatus(gl.FRAMEBUFFER) != gl.FRAMEBUFFER_COMPLETE) {
                debug("Skip: framebuffer is allowed to be incomplete.");
                return;
            }
            // Clear the FBO in order to make sure framebufferRenderbuffer is
            // committed.
            gl.clear(gl.COLOR_BUFFER_BIT | gl.STENCIL_BUFFER_BIT);
        }
        gl.bindRenderbuffer(gl.RENDERBUFFER, buffer);
        allocStorage(gl.RGBA4, params.alloc2.w, params.alloc2.h);
        gl.bindRenderbuffer(gl.RENDERBUFFER, stencilBuffer);
        allocStorage(gl.STENCIL_INDEX8, params.alloc2.w, params.alloc2.h);
    }

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

    if (gl.checkFramebufferStatus(gl.FRAMEBUFFER) != gl.FRAMEBUFFER_COMPLETE) {
        debug("Skip: framebuffer is allowed to be incomplete.");
        return;
    }
    wtu.glErrorShouldBe(gl, gl.NO_ERROR, 'should be no errors');

    // fbo depth should now be the default value of 0.

    // Draw a blue quad (stencil = 1) (should pass the stencil test: 1 > 0)
    gl.stencilFunc(gl.GREATER, 1, 0xffffffff);
    gl.enable(gl.STENCIL_TEST);
    wtu.setupColorQuad(gl);
    wtu.setFloatDrawColor(gl, [0, 0, 1, 1]);
    wtu.drawUnitQuad(gl);
    wtu.checkCanvasRect(gl, 0, 0, final.w, final.h,
                        [0, 0, 255, 255]);

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

    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>
</body>
</html>
