window.onload = main;

function main() {
  var canvas = document.getElementById("canvas");
  var gl = getWebGLContext(canvas);
  if (!gl) {
    return;
  }
  vertexShader = createShaderFromScriptElement(gl, "2d-vertex-shader");
  fragmentShader = createShaderFromScriptElement(gl, "2d-fragment-shader");
  program = createProgram(gl, [vertexShader, fragmentShader]);
  gl.useProgram(program);
  var positionLocation = gl.getAttribLocation(program, "a_position");
  var buffer = gl.createBuffer();
  gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([-1.0, -1.0, 1.0, -1.0, -1.0, 1.0, -1.0, 1.0, 1.0, -1.0, 1.0, 1.0]), gl.STATIC_DRAW);
  gl.enableVertexAttribArray(positionLocation);
  gl.vertexAttribPointer(positionLocation, 2, gl.FLOAT, false, 0, 0);
  gl.drawArrays(gl.TRIANGLES, 0, 6);
}
var setupWebGL = function (canvas, opt_attribs) {
  function showLink(str) {
    var container = canvas.parentNode;
    if (container) {
      container.innerHTML = makeFailHTML(str);
    }
  };
  if (!window.WebGLRenderingContext) {
    showLink(GET_A_WEBGL_BROWSER);
    return null;
  }
  var context = create3DContext(canvas, opt_attribs);
  if (!context) {
    showLink(OTHER_PROBLEM);
  }
  return context;
};
var create3DContext = function (canvas, opt_attribs) {
  var names = ["webgl", "experimental-webgl"];
  var context = null;
  for (var ii = 0; ii < names.length; ++ii) {
    try {
      context = canvas.getContext(names[ii], opt_attribs);
    } catch (e) {}
    if (context) {
      break;
    }
  }
  return context;
}
var updateCSSIfInIFrame = function () {
  if (isInIFrame()) {
    document.body.className = "iframe";
  }
};
var getWebGLContext = function (canvas) {
  if (isInIFrame()) {
    updateCSSIfInIFrame();
    canvas.width = canvas.clientWidth;
    canvas.height = canvas.clientHeight;
  } else {
    var title = document.getElementsByTagName("title")[0].innerText;
    var h1 = document.createElement("h1");
    h1.innerText = title;
    document.body.insertBefore(h1, document.body.children[0]);
  }
  var gl = setupWebGL(canvas);
  return gl;
};
var loadShader = function (gl, shaderSource, shaderType, opt_errorCallback) {
  var errFn = opt_errorCallback || error;
  var shader = gl.createShader(shaderType);
  gl.shaderSource(shader, shaderSource);
  gl.compileShader(shader);
  var compiled = gl.getShaderParameter(shader, gl.COMPILE_STATUS);
  if (!compiled) {
    lastError = gl.getShaderInfoLog(shader);
    errFn("*** Error compiling shader '" + shader + "':" + lastError);
    gl.deleteShader(shader);
    return null;
  }
  return shader;
}
var loadProgram = function (gl, shaders, opt_attribs, opt_locations) {
  var program = gl.createProgram();
  for (var ii = 0; ii < shaders.length; ++ii) {
    gl.attachShader(program, shaders[ii]);
  }
  if (opt_attribs) {
    for (var ii = 0; ii < opt_attribs.length; ++ii) {
      gl.bindAttribLocation(program, opt_locations ? opt_locations[ii] : ii, opt_attribs[ii]);
    }
  }
  gl.linkProgram(program);
  var linked = gl.getProgramParameter(program, gl.LINK_STATUS);
  if (!linked) {
    lastError = gl.getProgramInfoLog(program);
    error("Error in program linking:" + lastError);
    gl.deleteProgram(program);
    return null;
  }
  return program;
};
var createShaderFromScript = function (gl, scriptId, opt_shaderType, opt_errorCallback) {
  var shaderSource = "";
  var shaderType;
  var shaderScript = document.getElementById(scriptId);
  if (!shaderScript) {
    throw ("*** Error: unknown script element" + scriptId);
  }
  shaderSource = shaderScript.text;
  if (!opt_shaderType) {
    if (shaderScript.type == "x-shader/x-vertex") {
      shaderType = gl.VERTEX_SHADER;
    } else if (shaderScript.type == "x-shader/x-fragment") {
      shaderType = gl.FRAGMENT_SHADER;
    } else if (shaderType != gl.VERTEX_SHADER && shaderType != gl.FRAGMENT_SHADER) {
      throw ("*** Error: unknown shader type");
      return null;
    }
  }
  return loadShader(gl, shaderSource, opt_shaderType ? opt_shaderType : shaderType, opt_errorCallback);
};
this.createProgram = loadProgram;
this.createShaderFromScriptElement = createShaderFromScript;
this.getWebGLContext = getWebGLContext;
this.updateCSSIfInIFrame = updateCSSIfInIFrame;
window.requestAnimFrame = (function () {
  return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame || function (callback, element) {
    return window.setTimeout(callback, 1000 / 60);
  };
})();
window.cancelRequestAnimFrame = (function () {
  return window.cancelCancelRequestAnimationFrame || window.webkitCancelRequestAnimationFrame || window.mozCancelRequestAnimationFrame || window.oCancelRequestAnimationFrame || window.msCancelRequestAnimationFrame || window.clearTimeout;
})();