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webgl.js
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webgl.js
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GL_FLOAT_SIZE = 4;
GL_SHORT_SIZE = 2;
function initGL(canvasId){
var canvas = document.getElementById(canvasId);
try{
var gl = canvas.getContext("webgl") || canvas.getContext("experimental-webgl");
gl.aspect = canvas.width/canvas.height;
gl.viewWidth = canvas.width;
gl.viewHeight = canvas.height;
return gl;
}catch(ex){
alert("Unable to create WebGl Context");
}
return gl;
}
function initBuffer(gl, data, bufferType, vertSize, texCoordSize){
var buff = gl.createBuffer();
gl.bindBuffer(bufferType, buff);
if(bufferType == gl.ELEMENT_ARRAY_BUFFER){
gl.bufferData(bufferType, new Uint16Array(data), gl.STATIC_DRAW );
}else if(bufferType == gl.ARRAY_BUFFER){
gl.bufferData(bufferType, new Float32Array(data), gl.STATIC_DRAW);
}else{
return null;
}
var elementSize = texCoordSize + vertSize;
if(data.length % elementSize != 0){
alert("Invalid number of elements in buffer");
return null;
}
buff.vertSize = vertSize;
buff.texCoordSize = texCoordSize;
buff.elmSize = elementSize;
buff.numItems = data.length/buff.elmSize;
return buff;
}
function getShader (gl,shaderName) {
var shaderNode = document.getElementById(shaderName);
if(!shaderNode){
return null;
}
var shaderText = shaderNode.textContent;
if(!shaderText){
return null;
}
var shader;
if(shaderNode.type == "x-shader/x-fragment"){
shader = gl.createShader(gl.FRAGMENT_SHADER)
}else if(shaderNode.type == "x-shader/x-vertex"){
shader = gl.createShader(gl.VERTEX_SHADER)
}else{
return null;
}
gl.shaderSource(shader, shaderText);
gl.compileShader(shader);
if(!gl.getShaderParameter(shader,gl.COMPILE_STATUS)){
alert(gl.getShaderInfoLog(shader));
return null;
}
gl.shaderSource(shader, shaderText);
gl.compileShader(shader);
return shader;
}
function initTexture(gl, textName){
texture = gl.createTexture();
texture.image = new Image();
texture.image.onload = function(){
bindLoadedTexture(gl, texture);
}
texture.image.src = textName;
return texture;
}
function bindLoadedTexture(gl, texture){
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, texture.image);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
gl.bindTexture(gl.TEXTURE_2D, null);
}
function getProgram (gl,fragName, vertName, uniformNames, variableNames) {
var vertShader = getShader(gl, vertName);
var fragShader = getShader(gl, fragName);
var program = gl.createProgram();
gl.attachShader(program, vertShader);
gl.attachShader(program, fragShader);
gl.linkProgram(program);
if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
alert("Could not initialise shaders");
return null;
}
gl.useProgram(program);
for(var i = 0; i < uniformNames.length; i++){
program[uniformNames[i]] = gl.getUniformLocation(program, uniformNames[i]);
}
for(var i = 0; i < variableNames.length; i++){
program[variableNames[i]] = gl.getAttribLocation(program, variableNames[i]);
}
return program;
}
function main(){
var gl = initGL('webglCanvas');
gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.enable(gl.DEPTH_TEST);
var model = {
verts :
// Front face
[
-1.0, -1.0, 1.0, 0.0, 0.0,
1.0, -1.0, 1.0, 1.0, 0.0,
1.0, 1.0, 1.0, 1.0, 1.0,
-1.0, 1.0, 1.0, 0.0, 1.0,
// Back face
-1.0, -1.0, -1.0, 1.0, 0.0,
-1.0, 1.0, -1.0, 1.0, 1.0,
1.0, 1.0, -1.0, 0.0, 1.0,
1.0, -1.0, -1.0, 0.0, 0.0,
// Top face
-1.0, 1.0, -1.0, 0.0, 1.0,
-1.0, 1.0, 1.0, 0.0, 0.0,
1.0, 1.0, 1.0, 1.0, 0.0,
1.0, 1.0, -1.0, 1.0, 1.0,
// Bottom face
-1.0, -1.0, -1.0, 1.0, 1.0,
1.0, -1.0, -1.0, 0.0, 1.0,
1.0, -1.0, 1.0, 0.0, 0.0,
-1.0, -1.0, 1.0, 1.0, 0.0,
// Right face
1.0, -1.0, -1.0, 1.0, 0.0,
1.0, 1.0, -1.0, 1.0, 1.0,
1.0, 1.0, 1.0, 0.0, 1.0,
1.0, -1.0, 1.0, 0.0, 0.0,
// Left face
-1.0, -1.0, -1.0, 0.0,0.0,
-1.0, -1.0, 1.0, 1.0, 1.0,
-1.0, 1.0, 1.0, 1.0, 1.0,
-1.0, 1.0, -1.0, 0.0, 1.0],
indicies : [
0, 1, 2, 0, 2, 3, // Front face
4, 5, 6, 4, 6, 7, // Back face
8, 9, 10, 8, 10, 11, // Top face
12, 13, 14, 12, 14, 15, // Bottom face
16, 17, 18, 16, 18, 19, // Right face
20, 21, 22, 20, 22, 23] // Left face]
};
var vertBuff = initBuffer(gl, model.verts, gl.ARRAY_BUFFER , 4, 2);
var indexBuffer = initBuffer(gl, model.indicies, gl.ELEMENT_ARRAY_BUFFER , 1, 0);
var text2d = initTexture(gl, "bline.gif");
var program = getProgram(gl, 'shader-fs', 'shader-vs', ['pMatrix', 'mvMatrix','sampler'], ['VertexPosition', 'TextCoord']);
var model = mat4.create();
mat4.translate(model, model, [0, 0.0, -3.0]);
var perspective = mat4.perspective(mat4.create(), 90, gl.viewWidth/gl.viewHeight, 0.01, 1000);
frame(draw, gl, model, perspective, program, indexBuffer, vertBuff, text2d);
}
function frame (draw, gl, model, perspective, program, indexBuffer, vertBuff, text2d) {
model = animate(model);
draw(gl, model, perspective, program, indexBuffer, vertBuff, text2d);
requestAnimationFrame(function(){frame (draw, gl, model, perspective, program, indexBuffer, vertBuff, text2d);});
}
var lastTime = new Date().getTime();
function animate(model){
var time = new Date().getTime();
var delta = time - lastTime;
lastTime = time;
return mat4.rotate(model, model, (3.14159)*(delta/1000), [0.33, 1.0, -0.48]);
}
function draw(gl, mvMatrix,pMatrix, program, indexBuffer, vertexBuffer, text2d){
gl.viewport(0, 0, gl.viewWidth, gl.viewHeight);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
gl.useProgram(program);
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, text2d);
gl.uniform1i(program['sampler'], 0);
gl.uniformMatrix4fv(program['pMatrix'], false, pMatrix);
gl.uniformMatrix4fv(program['mvMatrix'], false, mvMatrix);
gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
gl.enableVertexAttribArray(program['VertexPosition']);
gl.vertexAttribPointer(program['VertexPosition'], vertexBuffer.vertSize, gl.FLOAT, false, vertexBuffer.elmSize * GL_FLOAT_SIZE, 0);
gl.enableVertexAttribArray(program['TextCoord']);
gl.vertexAttribPointer(program['TextCoord'], vertexBuffer.texCoordSize, gl.FLOAT, false, vertexBuffer.elmSize * GL_FLOAT_SIZE, vertexBuffer.vertSize * GL_FLOAT_SIZE);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
gl.drawElements(gl.TRIANGLES, indexBuffer.numItems,gl.UNSIGNED_SHORT, 0);
}