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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">
<title>WebGL Rendering and Sampling Feedback Loop Tests for Depth/Stencil Buffer</title>
<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="example" width="8" height="8"></canvas>
<div id="description"></div>
<div id="console"></div>

<script id="vshader" type="x-shader/x-vertex">#version 300 es
in highp vec4 aPosition;
in vec2 aTexCoord;
out vec2 texCoord;
void main() {
    gl_Position = aPosition;
    texCoord = aTexCoord;
}
</script>

<script id="fshader" type="x-shader/x-fragment">#version 300 es
precision mediump float;
uniform sampler2D tex;
in vec2 texCoord;
out vec4 oColor;
void main() {
    oColor = texture(tex, texCoord);
}
</script>

<script>
"use strict";

var wtu = WebGLTestUtils;
description("This test verifies the functionality of rendering to the same texture where it samples from.");

var gl = wtu.create3DContext("example", undefined, 2);

var width = 8;
var height = 8;
var tex0;
var tex1;
var tex2;
var fbo;
var program;
var positionLoc;
var texCoordLoc;

if (!gl) {
    testFailed("WebGL context does not exist");
} else {
    testPassed("WebGL context exists");

    init();
    detect_depth_stencil_feedback_loop();
    deinit();
}

function init() {
    // Setup program
    program = wtu.setupProgram(gl, ['vshader', 'fshader'], ['aPosition', 'aTexCoord'], [0, 1]);
    positionLoc = gl.getAttribLocation(program, "aPosition");
    texCoordLoc = gl.getAttribLocation(program, "aTexCoord");
    if (!program || positionLoc < 0 || texCoordLoc < 0) {
        testFailed("Set up program failed");
        return;
    }
    testPassed("Set up program succeeded");

    wtu.setupUnitQuad(gl, 0, 1);
    gl.viewport(0, 0, width, height);

    var texLoc = gl.getUniformLocation(program, "tex");
    gl.uniform1i(texLoc, 0);

    // Create textures and allocate storage
    tex0 = gl.createTexture();
    tex1 = gl.createTexture();
    tex2 = gl.createTexture();
    wtu.fillTexture(gl, tex0, width, height, [0x0, 0xff, 0x0, 0xff], 0, gl.RGBA, gl.UNSIGNED_BYTE, gl.RGBA);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
    wtu.fillTexture(gl, tex1, width, height, [0x80], 0, gl.DEPTH_COMPONENT, gl.UNSIGNED_INT, gl.DEPTH_COMPONENT16);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_COMPARE_MODE, gl.COMPARE_REF_TO_TEXTURE);
    wtu.fillTexture(gl, tex2, width, height, [0x40], 0, gl.DEPTH_STENCIL, gl.UNSIGNED_INT_24_8, gl.DEPTH24_STENCIL8);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_COMPARE_MODE, gl.COMPARE_REF_TO_TEXTURE);
    wtu.glErrorShouldBe(gl, gl.NO_ERROR, "Succeed to create textures.");

    fbo = gl.createFramebuffer();
    gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
    gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, tex0, 0);
}

function detect_depth_stencil_feedback_loop() {
    // Test rendering and sampling feedback loop for depth buffer
    gl.bindTexture(gl.TEXTURE_2D, tex1);
    gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.TEXTURE_2D, tex1, 0);
    if (gl.checkFramebufferStatus(gl.FRAMEBUFFER) != gl.FRAMEBUFFER_COMPLETE) {
        testFailed("Framebuffer incomplete.");
        return;
    }
    gl.enable(gl.DEPTH_TEST);
    wtu.clearAndDrawUnitQuad(gl);
    wtu.glErrorShouldBe(gl, gl.INVALID_OPERATION, "The test samples from a image. The same image is used as depth buffer during rendering.");

    gl.depthMask(gl.FALSE);
    wtu.clearAndDrawUnitQuad(gl);
    wtu.glErrorShouldBe(gl, gl.INVALID_OPERATION, "The test samples from a image. The same image is used as depth buffer. A feedback loop is formed regardless of the status of depth mask.");

    gl.depthMask(gl.TRUE);
    gl.disable(gl.DEPTH_TEST);
    wtu.clearAndDrawUnitQuad(gl);
    wtu.glErrorShouldBe(gl, gl.INVALID_OPERATION, "The test samples from a image. The same image is used as depth buffer. A feedback loop is formed regardless of whether the depth test is enabled.");

    // Test rendering and sampling feedback loop for stencil buffer
    gl.bindTexture(gl.TEXTURE_2D, tex2);
    gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.TEXTURE_2D, null, 0);
    gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.STENCIL_ATTACHMENT, gl.TEXTURE_2D, tex2, 0);
    if (gl.checkFramebufferStatus(gl.FRAMEBUFFER) != gl.FRAMEBUFFER_COMPLETE) {
        testFailed("Framebuffer incomplete.");
        return;
    }

    gl.enable(gl.STENCIL_TEST);
    wtu.clearAndDrawUnitQuad(gl);
    wtu.glErrorShouldBe(gl, gl.INVALID_OPERATION, "The test samples from a image. The same image is used as stencil buffer during rendering.");

    gl.stencilMask(0x0);
    wtu.clearAndDrawUnitQuad(gl);
    wtu.glErrorShouldBe(gl, gl.INVALID_OPERATION, "The test sampls from a image. The same image is used as stencil buffer. A feedback loop is formed regardless of the status of stencil mask.");

    gl.stencilMask(0xffff);
    gl.disable(gl.STENCIL_TEST);
    wtu.clearAndDrawUnitQuad(gl);
    wtu.glErrorShouldBe(gl, gl.INVALID_OPERATION, "The test samples from a image. The same image is used as stencil buffer. A feedback loop is formed regardless of whether the stencil test is enabled.");
}

function deinit() {
    gl.bindTexture(gl.TEXTURE_2D, null);
    gl.bindFramebuffer(gl.FRAMEBUFFER, null);
    gl.deleteTexture(tex0);
    gl.deleteTexture(tex1);
    gl.deleteTexture(tex2);
    gl.deleteFramebuffer(fbo);
}

var successfullyParsed = true;
</script>
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