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<title>WebGL - Fundamentals</title>
<style>
#c {
background-color: #fff;
border: 1px solid black;
position: absolute;
left: 100px;
top: 100px;
/* NOTE: This size is changed if in iframe - see below '.iframe canvas' */
width: 400px;
height: 300px;
display: block;
}
#c2 {
background-color: transparent;
border: 1px solid black;
position: absolute;
left: 100px;
top: 100px;
/* NOTE: This size is changed if in iframe - see below '.iframe canvas' */
width: 400px;
height: 300px;
display: block;
}
#c3 {
background-color: transparent;
border: 1px solid black;
position: absolute;
left: 100px;
top: 100px;
/* NOTE: This size is changed if in iframe - see below '.iframe canvas' */
width: 400px;
height: 300px;
display: block;
}
#c4 {
background-color: transparent;
border: 1px solid black;
position: absolute;
left: 100px;
top: 100px;
/* NOTE: This size is changed if in iframe - see below '.iframe canvas' */
width: 400px;
height: 300px;
display: block;
}
</style>
</head>
<body>
<canvas id="c"></canvas>
<canvas id="c2"></canvas><canvas id="c3"></canvas><canvas id="c4"></canvas>
</body>
</html>
<!--
for most samples webgl-utils only provides shader compiling/linking and
canvas resizing because why clutter the examples with code that's the same in every sample.
See http://webglfundamentals.org/webgl/lessons/webgl-boilerplate.html
and http://webglfundamentals.org/webgl/lessons/webgl-resizing-the-canvas.html
for webgl-utils, m3, m4, and webgl-lessons-ui.
-->
<script src="resources/webgl-utils.js"></script>
<script src="resources/webgl-lessons-helper.js"></script> <!-- you can and should delete this script. it is only used on the site to help with errors -->
<script id="2d-vertex-shader" type="notjs">
// an attribute will receive data from a buffer
attribute vec4 a_position;
varying vec4 v_color;
uniform vec2 u_scale;
// all shaders have a main function
void main() {
// gl_Position is a special variable a vertex shader
// is responsible for setting
gl_Position = a_position * vec4(u_scale,1,1);
gl_PointSize = 10.0;
v_color = gl_Position * vec4(1,1,0.5,1);
}
</script>
<script id="2d-vertex-shader2" type="notjs">
// an attribute will receive data from a buffer
attribute vec4 a_position;
varying vec4 v_color;
uniform vec2 u_scale;
// all shaders have a main function
void main() {
// gl_Position is a special variable a vertex shader
// is responsible for setting
gl_Position = a_position * vec4(u_scale,1,1);
gl_PointSize = 10.0;
v_color = gl_Position * vec4(1,1,0.5,1);
}
</script>
<script id="2d-fragment-shader" type="notjs">
// fragment shaders don't have a default precision so we need
// to pick one. mediump is a good default
precision mediump float;
varying vec4 v_color;
void main() {
// gl_FragColor is a special variable a fragment shader
// is responsible for setting
//gl_FragColor = vec4(0, 0, 1, 1); // return redish-purple
gl_FragColor = v_color;
}
</script>
<script id="2d-fragment-shader2" type="notjs">
// fragment shaders don't have a default precision so we need
// to pick one. mediump is a good default
precision mediump float;
varying vec4 v_color;
void main() {
// gl_FragColor is a special variable a fragment shader
// is responsible for setting
gl_FragColor = vec4(0, 0, 1, 1); // return redish-purple
//gl_FragColor = v_color;
}
</script>
<script>
"use strict";
function createShader(gl, type, source) {
var shader = gl.createShader(type);
gl.shaderSource(shader, source);
gl.compileShader(shader);
var success = gl.getShaderParameter(shader, gl.COMPILE_STATUS);
if (success) {
return shader;
}
console.log(gl.getShaderInfoLog(shader));
gl.deleteShader(shader);
}
function createProgram(gl, vertexShader, fragmentShader) {
var program = gl.createProgram();
gl.attachShader(program, vertexShader);
gl.attachShader(program, fragmentShader);
gl.linkProgram(program);
var success = gl.getProgramParameter(program, gl.LINK_STATUS);
if (success) {
return program;
}
console.log(gl.getProgramInfoLog(program));
gl.deleteProgram(program);
}
function main() {
// Get A WebGL context
var canvas = document.getElementById("c");
var gl = canvas.getContext("webgl");
if (!gl) {
return;
}
var scale_x = 1;
var scale_y = 1;
// Get the strings for our GLSL shaders
var vertexShaderSource = document.getElementById("2d-vertex-shader").text;
var fragmentShaderSource = document.getElementById("2d-fragment-shader").text;
// create GLSL shaders, upload the GLSL source, compile the shaders
var vertexShader = createShader(gl, gl.VERTEX_SHADER, vertexShaderSource);
console.log(vertexShader)
var fragmentShader = createShader(gl, gl.FRAGMENT_SHADER, fragmentShaderSource);
// Link the two shaders into a program
var program = createProgram(gl, vertexShader, fragmentShader);
// Create a buffer and put three 2d clip space points in it
var positionBuffer = gl.createBuffer();
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
var ps = []
var positions = [
0, 0,
0, 0.8,
0.7, 0,
];
ps.push(positions);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(positions), gl.STATIC_DRAW);
// code above this line is initialization code.
// code below this line is rendering code.
webglUtils.resizeCanvasToDisplaySize(gl.canvas);
// Tell WebGL how to convert from clip space to pixels
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
// Clear the canvas
gl.clearColor(0, 0, 0, 0);
gl.clear(gl.COLOR_BUFFER_BIT);
// Tell it to use our program (pair of shaders)
gl.useProgram(program);
// look up where the vertex data needs to go.
var positionAttributeLocation = gl.getAttribLocation(program, "a_position");
// Turn on the attribute
gl.enableVertexAttribArray(positionAttributeLocation);
// Bind the position buffer.
//gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// Tell the attribute how to get data out of positionBuffer (ARRAY_BUFFER)
var size = 2; // 2 components per iteration
var type = gl.FLOAT; // the data is 32bit floats
var normalize = false; // don't normalize the data
var stride = 0; // 0 = move forward size * sizeof(type) each iteration to get the next position
var offset = 0; // start at the beginning of the buffer
gl.vertexAttribPointer(
positionAttributeLocation, size, type, normalize, stride, offset)
// look up uniform locations
var resolutionUniformLocation = gl.getUniformLocation(program, "u_scale");
gl.uniform2f(resolutionUniformLocation, scale_x, scale_y);
// draw
//POINTS
//LINES
//LINE_LOOP
//LINE_STRIP
//TRIANGLES
var primitiveType = gl.LINE_STRIP;
var offset = 0;
var count = 3;
gl.drawArrays(primitiveType, offset, count);
}
main();
function main2() {
// Get A WebGL context
var canvas = document.getElementById("c2");
var gl = canvas.getContext("webgl");
if (!gl) {
return;
}
var scale_x = 1;
var scale_y = 1;
// Get the strings for our GLSL shaders
var vertexShaderSource = document.getElementById("2d-vertex-shader").text;
var fragmentShaderSource = document.getElementById("2d-fragment-shader").text;
// create GLSL shaders, upload the GLSL source, compile the shaders
var vertexShader = createShader(gl, gl.VERTEX_SHADER, vertexShaderSource);
console.log(vertexShader)
var fragmentShader = createShader(gl, gl.FRAGMENT_SHADER, fragmentShaderSource);
// Link the two shaders into a program
var program = createProgram(gl, vertexShader, fragmentShader);
// Create a buffer and put three 2d clip space points in it
var positionBuffer = gl.createBuffer();
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
var ps = []
var positions = [
0, 0,
0, -0.8,
0.7, 0,
];
ps.push(positions);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(positions), gl.STATIC_DRAW);
// code above this line is initialization code.
// code below this line is rendering code.
webglUtils.resizeCanvasToDisplaySize(gl.canvas);
// Tell WebGL how to convert from clip space to pixels
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
// Clear the canvas
gl.clearColor(0, 0, 0, 0);
gl.clear(gl.COLOR_BUFFER_BIT);
// Tell it to use our program (pair of shaders)
gl.useProgram(program);
// look up where the vertex data needs to go.
var positionAttributeLocation = gl.getAttribLocation(program, "a_position");
// Turn on the attribute
gl.enableVertexAttribArray(positionAttributeLocation);
// Bind the position buffer.
//gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// Tell the attribute how to get data out of positionBuffer (ARRAY_BUFFER)
var size = 2; // 2 components per iteration
var type = gl.FLOAT; // the data is 32bit floats
var normalize = false; // don't normalize the data
var stride = 0; // 0 = move forward size * sizeof(type) each iteration to get the next position
var offset = 0; // start at the beginning of the buffer
gl.vertexAttribPointer(
positionAttributeLocation, size, type, normalize, stride, offset)
// look up uniform locations
var resolutionUniformLocation = gl.getUniformLocation(program, "u_scale");
gl.uniform2f(resolutionUniformLocation, scale_x, scale_y);
// draw
//POINTS
//LINES
//LINE_LOOP
//LINE_STRIP
//TRIANGLES
var primitiveType = gl.TRIANGLES;
var offset = 0;
var count = 3;
gl.drawArrays(primitiveType, offset, count);
}
main2();
function main3() {
// Get A WebGL context
var canvas = document.getElementById("c3");
var gl = canvas.getContext("webgl");
if (!gl) {
return;
}
var scale_x = 1;
var scale_y = 1;
// Get the strings for our GLSL shaders
var vertexShaderSource = document.getElementById("2d-vertex-shader").text;
var fragmentShaderSource = document.getElementById("2d-fragment-shader").text;
// create GLSL shaders, upload the GLSL source, compile the shaders
var vertexShader = createShader(gl, gl.VERTEX_SHADER, vertexShaderSource);
console.log(vertexShader)
var fragmentShader = createShader(gl, gl.FRAGMENT_SHADER, fragmentShaderSource);
// Link the two shaders into a program
var program = createProgram(gl, vertexShader, fragmentShader);
// Create a buffer and put three 2d clip space points in it
var positionBuffer = gl.createBuffer();
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
var ps = []
var positions = [
0, 0,
0, -0.8,
-0.7, 0,
];
ps.push(positions);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(positions), gl.STATIC_DRAW);
// code above this line is initialization code.
// code below this line is rendering code.
webglUtils.resizeCanvasToDisplaySize(gl.canvas);
// Tell WebGL how to convert from clip space to pixels
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
// Clear the canvas
gl.clearColor(0, 0, 0, 0);
gl.clear(gl.COLOR_BUFFER_BIT);
// Tell it to use our program (pair of shaders)
gl.useProgram(program);
// look up where the vertex data needs to go.
var positionAttributeLocation = gl.getAttribLocation(program, "a_position");
// Turn on the attribute
gl.enableVertexAttribArray(positionAttributeLocation);
// Bind the position buffer.
//gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// Tell the attribute how to get data out of positionBuffer (ARRAY_BUFFER)
var size = 2; // 2 components per iteration
var type = gl.FLOAT; // the data is 32bit floats
var normalize = false; // don't normalize the data
var stride = 0; // 0 = move forward size * sizeof(type) each iteration to get the next position
var offset = 0; // start at the beginning of the buffer
gl.vertexAttribPointer(
positionAttributeLocation, size, type, normalize, stride, offset)
// look up uniform locations
var resolutionUniformLocation = gl.getUniformLocation(program, "u_scale");
gl.uniform2f(resolutionUniformLocation, scale_x, scale_y);
// draw
//POINTS
//LINES
//LINE_LOOP
//LINE_STRIP
//TRIANGLES
var primitiveType = gl.LINE_STRIP;
var offset = 0;
var count = 3;
gl.drawArrays(primitiveType, offset, count);
}
main3();
function main4() {
// Get A WebGL context
var canvas = document.getElementById("c4");
var gl = canvas.getContext("webgl");
if (!gl) {
return;
}
var scale_x = 1;
var scale_y = 1;
// Get the strings for our GLSL shaders
var vertexShaderSource = document.getElementById("2d-vertex-shader").text;
var fragmentShaderSource = document.getElementById("2d-fragment-shader").text;
// create GLSL shaders, upload the GLSL source, compile the shaders
var vertexShader = createShader(gl, gl.VERTEX_SHADER, vertexShaderSource);
console.log(vertexShader)
var fragmentShader = createShader(gl, gl.FRAGMENT_SHADER, fragmentShaderSource);
// Link the two shaders into a program
var program = createProgram(gl, vertexShader, fragmentShader);
// Create a buffer and put three 2d clip space points in it
var positionBuffer = gl.createBuffer();
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
var ps = []
var positions = [
0, 0,
0, 0.8,
-0.7, 0,
];
ps.push(positions);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(positions), gl.STATIC_DRAW);
// code above this line is initialization code.
// code below this line is rendering code.
webglUtils.resizeCanvasToDisplaySize(gl.canvas);
// Tell WebGL how to convert from clip space to pixels
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
// Clear the canvas
gl.clearColor(0, 0, 0, 0);
gl.clear(gl.COLOR_BUFFER_BIT);
// Tell it to use our program (pair of shaders)
gl.useProgram(program);
// look up where the vertex data needs to go.
var positionAttributeLocation = gl.getAttribLocation(program, "a_position");
// Turn on the attribute
gl.enableVertexAttribArray(positionAttributeLocation);
// Bind the position buffer.
//gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// Tell the attribute how to get data out of positionBuffer (ARRAY_BUFFER)
var size = 2; // 2 components per iteration
var type = gl.FLOAT; // the data is 32bit floats
var normalize = false; // don't normalize the data
var stride = 0; // 0 = move forward size * sizeof(type) each iteration to get the next position
var offset = 0; // start at the beginning of the buffer
gl.vertexAttribPointer(
positionAttributeLocation, size, type, normalize, stride, offset)
// look up uniform locations
var resolutionUniformLocation = gl.getUniformLocation(program, "u_scale");
gl.uniform2f(resolutionUniformLocation, scale_x, scale_y);
// draw
//POINTS
//LINES
//LINE_LOOP
//LINE_STRIP
//TRIANGLES
var primitiveType = gl.TRIANGLES;
var offset = 0;
var count = 3;
gl.drawArrays(primitiveType, offset, count);
var flag = false;
document.onclick = function(){
if (!flag){
gl.clearColor(0, 0, 0, 0);
gl.clear(gl.COLOR_BUFFER_BIT);
flag = true;
}else{
gl.drawArrays(primitiveType, offset, count);
flag = false;
}
}
}
main4();
</script>
