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webgl-utils.js
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webgl-utils.js
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window.onerror = function(msg, url, lineno) {
alert(url + '(' + lineno + '): ' + msg);
}
function createShader(str, type) {
var shader = gl.createShader(type);
gl.shaderSource(shader, str);
gl.compileShader(shader);
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
throw gl.getShaderInfoLog(shader);
}
return shader;
}
function createProgram(vstr, fstr) {
var program = gl.createProgram();
var vshader = createShader(vstr, gl.VERTEX_SHADER);
var fshader = createShader(fstr, gl.FRAGMENT_SHADER);
gl.attachShader(program, vshader);
gl.attachShader(program, fshader);
gl.linkProgram(program);
if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
throw gl.getProgramInfoLog(program);
}
return program;
}
function screenQuad() {
var vertexPosBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, vertexPosBuffer);
var vertices = [-1, -1, 1, -1, -1, 1, 1, 1];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
vertexPosBuffer.itemSize = 2;
vertexPosBuffer.numItems = 4;
/*
2___3
|\ |
| \ |
|__\|
0 1
*/
return vertexPosBuffer;
}
function linkProgram(program) {
var vshader = createShader(program.vshaderSource, gl.VERTEX_SHADER);
var fshader = createShader(program.fshaderSource, gl.FRAGMENT_SHADER);
gl.attachShader(program, vshader);
gl.attachShader(program, fshader);
gl.linkProgram(program);
if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
throw gl.getProgramInfoLog(program);
}
}
function loadFile(file, callback, noCache, isJson) {
var request = new XMLHttpRequest();
request.onreadystatechange = function() {
if (request.readyState == 1) {
if (isJson) {
request.overrideMimeType('application/json');
}
request.send();
} else if (request.readyState == 4) {
if (request.status == 200) {
callback(request.responseText);
} else if (request.status == 404) {
throw 'File "' + file + '" does not exist.';
} else {
throw 'XHR error ' + request.status + '.';
}
}
};
var url = file;
if (noCache) {
url += '?' + (new Date()).getTime();
}
request.open('GET', url, true);
}
function loadProgram(vs, fs, callback) {
var program = gl.createProgram();
function vshaderLoaded(str) {
program.vshaderSource = str;
if (program.fshaderSource) {
linkProgram(program);
callback(program);
}
}
function fshaderLoaded(str) {
program.fshaderSource = str;
if (program.vshaderSource) {
linkProgram(program);
callback(program);
}
}
loadFile(vs, vshaderLoaded, true);
loadFile(fs, fshaderLoaded, true);
return program;
}
(function() {
var lastTime = 0;
var vendors = ['ms', 'moz', 'webkit', 'o'];
for(var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x) {
window.requestAnimationFrame = window[vendors[x]+'RequestAnimationFrame'];
window.cancelRequestAnimationFrame = window[vendors[x]+
'CancelRequestAnimationFrame'];
}
if (!window.requestAnimationFrame)
window.requestAnimationFrame = function(callback, element) {
var currTime = new Date().getTime();
var timeToCall = Math.max(0, 16 - (currTime - lastTime));
var id = window.setTimeout(function() { callback(currTime + timeToCall); },
timeToCall);
lastTime = currTime + timeToCall;
return id;
};
if (!window.cancelAnimationFrame)
window.cancelAnimationFrame = function(id) {
clearTimeout(id);
};
}())