<!--
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">
<title>WebGL Framebuffer state restoration Test</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="50" height="50">
</canvas>
<div id="description"></div>
<div id="console"></div>
<script>
"use strict";
var wtu = WebGLTestUtils;
description();

function test() {
  var gl = wtu.create3DContext("example", {preserveDrawingBuffer: true});
  if (!gl) {
    testFailed("context does not exist");
    finishTest();
    return;
  }
  var program = wtu.setupColorQuad(gl);
  var colorLoc = gl.getUniformLocation(program, "u_color");
  gl.enable(gl.DEPTH_TEST);
  gl.depthFunc(gl.LESS);

  var testDrawToBackBuffer = function(label) {
    debug("");
    debug("drawing to backbuffer " + label);
    gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
    // Draw in green
    gl.uniform4fv(colorLoc, [0, 1, 0, 1]);
    gl.drawArrays(gl.TRIANGLES, 0, 6);
    wtu.checkCanvas(gl, [0, 255, 0, 255], "should be green");
    // Draw in red, should not draw because of depth test.
    gl.uniform4fv(colorLoc, [1, 0, 0, 1]);
    gl.drawArrays(gl.TRIANGLES, 0, 6);
    wtu.checkCanvas(gl, [0, 255, 0, 255], "should still be green");
  }

  var testDrawToFBO = function(label ) {
    debug("");
    debug("drawing to framebuffer " + label);
    // Draw in green
    gl.uniform4fv(colorLoc, [0, 1, 0, 1]);
    gl.drawArrays(gl.TRIANGLES, 0, 6);
    wtu.checkCanvas(gl, [0, 255, 0, 255], "should be green");
    // Draw in red as there is not depth buffer.
    gl.uniform4fv(colorLoc, [1, 0, 0, 1]);
    gl.drawArrays(gl.TRIANGLES, 0, 6);
    wtu.checkCanvas(gl, [255, 0, 0, 255], "should be red");
  }

  testDrawToBackBuffer("start");

  var fbo = gl.createFramebuffer();
  var tex = gl.createTexture();
  gl.bindTexture(gl.TEXTURE_2D, tex);
  gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, 50, 50, 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, fbo);
  gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, tex, 0);
  if (gl.checkFramebufferStatus(gl.FRAMEBUFFER) != gl.FRAMEBUFFER_COMPLETE) {
    finishTest();
    return;
  }

  wtu.checkCanvas(gl, [0, 0, 0, 0], "should be zero");
  testDrawToFBO("start");

  gl.bindFramebuffer(gl.FRAMEBUFFER, null);
  testDrawToBackBuffer("after drawing to framebuffer");

  gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
  testDrawToFBO("after drawing to backbuffer");

  gl.bindFramebuffer(gl.FRAMEBUFFER, null);
  wtu.waitForComposite(function() {
    testDrawToBackBuffer("after composite");
    gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
    testDrawToFBO("after drawing to backbuffer after composite");
    wtu.waitForComposite(function() {
      testDrawToFBO("after composite");
      gl.bindFramebuffer(gl.FRAMEBUFFER, null);
      testDrawToBackBuffer("after drawing to framebuffer after composite");

      wtu.glErrorShouldBe(gl, gl.NO_ERROR, "should be no errors");
      finishTest();
    });
  });
}
test();

var successfullyParsed = true;
</script>
</body>
</html>

