Adding some basic color from the last bl.ock to demonstrate the basics of color w/ webgl. Though the author of the tutorial calls it colour. http://learningwebgl.com/blog/?p=134
<html>
<head>
<script type="text/javascript" src="//bl.ocks.org/mpmckenna8/raw/5991cabbde44869c41aa/b8552346660d39acbddee5e29591dc4d77c9abe6/glMatrix-0.9.5.min.js"></script>
<script id="shader-fs" type="x-shader/x-fragment">
precision mediump float;
varying vec4 vColor;
void main(void){
gl_FragColor = vColor;
}
</script>
<script id="shader-vs" type="x-shader/x-vertex">
attribute vec3 aVertexPosition;
attribute vec4 aVertexColor;
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
varying vec4 vColor;
void main(void){
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
vColor = aVertexColor;
}
</script>
<script type="text/javascript">
var gl;
var mvMatrix = mat4.create();
var pMatrix = mat4.create();
var shaderProgram;
function initGL(canvas){
try {
gl = canvas.getContext("experimental-webgl");
gl.viewportWidth = canvas.width;
gl.viewportHeight = canvas.height;
}
catch(e){
console.log('cught', e);
}
if(!gl){
alert("couldnt get webgl initialized")
}
}
function getShader(gl, id){
var shaderScript = document.getElementById(id);
if(!shaderScript){
return null;
}
var str = "";
var k = shaderScript.firstChild;
while(k){
if(k.nodeType == 3){
str += k.textContent;
}
k = k.nextSibling;
}
var shader;
if(shaderScript.type == "x-shader/x-fragment"){
shader = gl.createShader(gl.FRAGMENT_SHADER);
}
else if(shaderScript.type == "x-shader/x-vertex"){
shader = gl.createShader(gl.VERTEX_SHADER);
}
else{
return null;
}
gl.shaderSource(shader, str);
gl.compileShader(shader);
if(!gl.getShaderParameter(shader, gl.COMPILE_STATUS)){
alert('getting shader went wrong', gl.getShaderInfoLog(shader));
return null;
}
return shader;
}
function setMatrixUniforms(){
gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, pMatrix);
gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, mvMatrix);
}
var triangleVertexPositionBuffer;
var triangleVertexColorBuffer;
var squareVertexPositionBuffer;
function initBuffers(){
triangleVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexPositionBuffer);
var vertices = [
0.0, 1.0, 0.0,
-1.0, -1.0, 0.0,
1.0, -1.0, 0.0
];
console.log(vertices)
console.log(vertices)
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
triangleVertexPositionBuffer.itemSize = 3;
triangleVertexPositionBuffer.numItems = 3;
triangleVertexColorBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexColorBuffer);
var colors = [
1.0, 0.0, 0.0, 1.0,
0.0, 1.0, 0.0, 1.0,
0.0, 0.0, 1.0, 1.0
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW);
triangleVertexColorBuffer.itemSize = 4;
triangleVertexColorBuffer.numItems = 3;
squareVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer);
vertices = [
1.0, 1.0, 0.0,
-1.0, 1.0, 0.0,
1.0, -1.0, 0.0,
-1.0, -1.0, 0.0
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
squareVertexPositionBuffer.itemSize = 3;
squareVertexPositionBuffer.numItems = 4;;
squareVertexColorBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexColorBuffer);
colors = [];
for (var i=0; i < 4; i++) {
// colors = colors.concat([0.8, 0.5, 1.0, 1.0]);
if(i == 0 || i ==2){
colors = colors.concat([0.2, .8, 0.1, 1.0])
}
else{
colors = colors.concat([1.0,0.0,0.0,1.0])
}
}
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW);
squareVertexColorBuffer.itemSize = 4;
squareVertexColorBuffer.numItems = 4;
}
function drawScene(){
gl.viewport(0.0, 0.0, gl.viewportWidth,gl.viewportHeight);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
mat4.perspective(45, gl.viewportWidth / gl.viewportHeight, 0.1, 100.0, pMatrix);
mat4.identity(mvMatrix);
mat4.translate(mvMatrix, [-1.5, 0.0, -7.0]);
gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, triangleVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexColorBuffer)
gl.vertexAttribPointer(shaderProgram.vertexColorAttribute, triangleVertexColorBuffer.itemSize, gl.FLOAT, false, 0.0, 0.0)
setMatrixUniforms();
gl.drawArrays(gl.TRIANGLES, 0, triangleVertexPositionBuffer.numItems);
mat4.translate(mvMatrix,[2.0, -1.0, 1.0]);
gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, squareVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexColorBuffer);
gl.vertexAttribPointer(shaderProgram.vertexColorAttribute, squareVertexColorBuffer.itemSize, gl.FLOAT, false, 0, 0);
setMatrixUniforms();
gl.drawArrays(gl.TRIANGLE_STRIP, 0, squareVertexPositionBuffer.numItems);
}
function initShaders(){
var fragmentShader = getShader(gl, "shader-fs");
var vertexShader = getShader(gl, "shader-vs");
shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram(shaderProgram);
if(!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)){
alert('colulnt initialize shaders in initShaders')
}
gl.useProgram(shaderProgram);
shaderProgram.vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition");
gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute);
shaderProgram.vertexColorAttribute = gl.getAttribLocation(shaderProgram, "aVertexColor");
gl.enableVertexAttribArray(shaderProgram.vertexColorAttribute)
shaderProgram.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
}
function webGLStart(){
var canvas = document.getElementById("lesson01-canvas");
initGL(canvas);
initShaders();
initBuffers();
gl.clearColor(0.0, 0.0,0.0,1.0);
gl.enable(gl.DEPTH_TEST);
drawScene();
}
</script>
</head>
<body onload="webGLStart();">
<canvas id="lesson01-canvas" style="border: black;" width="500" height="500">
</canvas>
<br/>
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