<!--
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 Lots of polygons example.</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="1024" height="1024" style="width: 40px; height: 40px;">
</canvas>
<div id="description"></div>
<div id="console"></div>
<script>
"use strict";
window.onload = init;
debug("Tests a WebGL program that draws a bunch of large polygons");

function init() {
  if (confirm(
      "After clicking OK your machine may become unresponsive or crash.")) {
    main();
  } else {
    debug("cancelled");
  }
}

function main() {
  var wtu = WebGLTestUtils;
  var canvas = document.getElementById("example");
  canvas.addEventListener("webglcontextlost", function(e) { e.preventDefault(); }, false);
  canvas.addEventListener("webglcontextrestored", function(e) { }, false);

  var gl = wtu.create3DContext(canvas);
  var program = wtu.setupTexturedQuad(gl);

  assertMsg(gl.getError() == gl.NO_ERROR, "Should be no errors from setup.");

  var tex = gl.createTexture();
  gl.enable(gl.BLEND);
  gl.disable(gl.DEPTH_TEST);

  wtu.fillTexture(gl, tex, 4096, 4096, [0, 192, 128, 255], 0);
  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "after creating texture");

  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);
  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "after setting texture params");

  var loc = gl.getUniformLocation(program, "tex");
  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "after getting tex locations");
  gl.uniform1i(loc, 0);
  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "after setting tex uniform");

  var numQuads = 100000;
  var indexBuf = new ArrayBuffer(numQuads * 6);
  var indices = new Uint8Array(indexBuf);
  for (var ii = 0; ii < numQuads; ++ii) {
    var offset = ii * 6;
    indices[offset + 0] = 0;
    indices[offset + 1] = 1;
    indices[offset + 2] = 2;
    indices[offset + 3] = 3;
    indices[offset + 4] = 4;
    indices[offset + 5] = 5;
  }
  var indexBuffer = gl.createBuffer();
  gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
  gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, indices, gl.STATIC_DRAW);
  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "after creating index buffer");
  gl.drawElements(gl.TRIANGLES, numQuads * 6, gl.UNSIGNED_BYTE, 0);
  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "after drawing");

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


