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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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<head>
<meta charset="utf-8">
<title>WebGL WEBGL_draw_buffers Conformance Tests</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>
<script src="../../js/tests/webgl-draw-buffers-utils.js"></script>
</head>
<body>
<div id="description"></div>
<canvas id="canvas" width="64" height="64"> </canvas>
<div id="console"></div>
<script id="fshaderRedWithReturn" type="x-shader/x-fragment">
#extension GL_EXT_draw_buffers : require
precision mediump float;
uniform float u_zero;
void main() {
    gl_FragColor = vec4(1,0,0,1);
    if (u_zero < 1.0) {
        return;
    }
    gl_FragColor = vec4(0,0,1,1);
}
</script>
<script id="fshaderWithDiscard" type="x-shader/x-fragment">
#extension GL_EXT_draw_buffers : require
precision mediump float;
uniform float u_zero;
void main() {
    gl_FragColor = vec4(1,0,0,1);
    if (u_zero < 1.0) {
        discard;
    }
    gl_FragColor = vec4(0,0,1,1);
}
</script>
<script>
"use strict";
description("This test verifies gl_FragColor being broadcasted when using WEBGL_draw_buffers extension, if it is available.");

debug("");

var wtu = WebGLTestUtils;
var canvas = document.getElementById("canvas");
var gl = wtu.create3DContext(canvas);
var ext = null;
var drawBuffersUtils;

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

  // Query the extension and store globally so shouldBe can access it
  ext = gl.getExtension("WEBGL_draw_buffers");
  if (!ext) {
    testPassed("No WEBGL_draw_buffers support -- this is legal");
  } else {
    testPassed("Successfully enabled WEBGL_draw_buffers extension");
    drawBuffersUtils = WebGLDrawBuffersUtils(gl, ext);
    runDrawTests();
  }
}

function runDrawTests() {
  debug("");
  var fb = gl.createFramebuffer();

  var maxUsable = drawBuffersUtils.getMaxUsableColorAttachments();
  var bufs = drawBuffersUtils.makeColorAttachmentArray(maxUsable);

  var width = 64;
  var height = 64;
  var attachments = [];
  for (var ii = 0; ii < maxUsable; ++ii) {
    var tex = gl.createTexture();
    gl.bindTexture(gl.TEXTURE_2D, tex);
    gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, width, height, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);
    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_WRAP_S, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
    gl.bindFramebuffer(gl.FRAMEBUFFER, fb);
    gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0 + ii, gl.TEXTURE_2D, tex, 0);
    attachments.push({
      texture: tex
    });
  }

  debug("test that gl_FragColor broadcasts if extension is enabled in fragment shader and fragment shader main returns in the middle");
  gl.bindFramebuffer(gl.FRAMEBUFFER, fb);
  ext.drawBuffersWEBGL(bufs);
  var redProgramWithReturn = wtu.setupProgram(gl, [wtu.simpleVertexShader, "fshaderRedWithReturn"], ["vPosition"], undefined, true);
  shouldBe("gl.checkFramebufferStatus(gl.FRAMEBUFFER)", "gl.FRAMEBUFFER_COMPLETE");
  gl.clearColor(0, 0, 0, 0);
  gl.clear(gl.COLOR_BUFFER_BIT);
  gl.useProgram(redProgramWithReturn);
  wtu.drawUnitQuad(gl);
  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "after draw");

  drawBuffersUtils.checkAttachmentsForColor(attachments, [255, 0, 0, 255]);

  debug("test that none of the attachments are written in case the fragment shader discards");
  gl.bindFramebuffer(gl.FRAMEBUFFER, fb);
  ext.drawBuffersWEBGL(bufs);
  var programWithDiscard = wtu.setupProgram(gl, [wtu.simpleVertexShader, "fshaderWithDiscard"], ["vPosition"], undefined, true);
  gl.clearColor(0, 0, 0, 0);
  gl.clear(gl.COLOR_BUFFER_BIT);
  gl.useProgram(programWithDiscard);
  wtu.drawUnitQuad(gl);
  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "after draw");

  drawBuffersUtils.checkAttachmentsForColor(attachments, [0, 0, 0, 0]);

  gl.bindTexture(gl.TEXTURE_2D, null);
  gl.bindFramebuffer(gl.FRAMEBUFFER, null);
  gl.deleteFramebuffer(fb);
  attachments.forEach(function(attachment) {
    gl.deleteTexture(attachment.texture);
  });
  gl.deleteProgram(redProgramWithReturn);
  gl.deleteProgram(programWithDiscard);
}

var successfullyParsed = true;

</script>
<script src="../../js/js-test-post.js"></script>
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