<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
</head>
<body>
<canvas id="canvas" width="600" height="600"></canvas>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/gl-matrix/2.3.2/gl-matrix-min.js"></script>
<script id="shader-vs" type="x-shader/x-vertex">
attribute vec4 coords;
attribute float pointSize;
uniform mat4 transformMatrix;
uniform mat4 perspectiveMatrix;
attribute vec4 colors;
varying vec4 varyingColors;
void main(void) {
gl_Position = perspectiveMatrix * transformMatrix * coords;
gl_PointSize = pointSize;
varyingColors = colors;
}
</script>
<script id="shader-fs" type="x-shader/x-fragment">
precision mediump float;
uniform vec4 color;
varying vec4 varyingColors;
void main(void) {
gl_FragColor = varyingColors;
}
</script>
<script src="lib/script.js"></script>
</body>
</html>
var gl,
shaderProgram,
vertices,
matrix = mat4.create(),
vertexCount = 36;
initGL();
createShaders();
createVertices();
draw();
function initGL() {
var canvas = document.getElementById("canvas");
gl = canvas.getContext("webgl");
gl.enable(gl.DEPTH_TEST);
gl.viewport(0, 0, canvas.width, canvas.height);
gl.clearColor(1, 1, 1, 1);
}
function createShaders() {
var vertexShader = getShader(gl, "shader-vs");
var fragmentShader = getShader(gl, "shader-fs");
shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram(shaderProgram);
gl.useProgram(shaderProgram);
}
function createVertices() {
vertices = [
0.88, -0.25, -0.18, 1, 0, 0, 1,
0.9, 0.25, 0, 1, 0, 0, 1,
0.88, -0.25, 0.18, 1, 0, 0, 1,
0.85, -0.25, 0.29, 1, 1, 0, 1,
0.78, 0.25, 0.45, 1, 1, 0, 1,
0.67, -0.25, 0.6, 1, 1, 0, 1,
0.6, -0.25, 0.67, 0, 1, 0, 1,
0.45, 0.25, 0.78, 0, 1, 0, 1,
0.29, -0.25, 0.85, 0, 1, 0, 1,
0.18, -0.25, 0.88, 0, 1, 1, 1,
0, 0.25, 0.9, 0, 1, 1, 1,
-0.18, -0.25, 0.88, 0, 1, 1, 1,
-0.29, -0.25, 0.85, 0, 0, 1, 1,
-0.45, 0.25, 0.78, 1, 1, 0, 1,
-0.6, -0.25, 0.67, 0, 0, 1, 1,
-0.67, -0.25, 0.6, 1, 0, 1, 1,
-0.78, 0.25, 0.45, 1, 0, 1, 1,
-0.85, -0.25, 0.29, 1, 0, 1, 1,
-0.88, -0.25, 0.18, 1, 0.5, 0, 1,
-0.9, 0.25, 0, 1, 0.5, 0, 1,
-0.88, -0.25, -0.18, 1, 0.5, 0, 1,
-0.85, -0.25, -0.29, 0, 0.5, 1, 1,
-0.78, 0.25, -0.45, 0, 0.5, 1, 1,
-0.67, -0.25, -0.6, 0, 0.5, 1, 1,
-0.6, -0.25, -0.67, 0, 1, 0.5, 1,
-0.45, 0.25, -0.78, 0, 1, 0.5, 1,
-0.29, -0.25, -0.85, 0, 1, 0.5, 1,
-0.18, -0.25, -0.88, 1, 0, 0.5, 1,
0, 0.25, -0.9, 1, 0, 0.5, 1,
0.18, -0.25, -0.88, 1, 0, 0.5, 1,
0.29, -0.25, -0.85, 0.5, 1, 0, 1,
0.45, 0.25, -0.78, 0.5, 1, 0, 1,
0.6, -0.25, -0.67, 0.5, 1, 0, 1,
0.67, -0.25, -0.6, 0.5, 0, 1, 1,
0.78, 0.25, -0.45, 0.5, 0, 1, 1,
0.85, -0.25, -0.29, 0.5, 0, 1, 1
];
var buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
var coords = gl.getAttribLocation(shaderProgram, "coords");
gl.vertexAttribPointer(coords, 3, gl.FLOAT, false, Float32Array.BYTES_PER_ELEMENT * 7, 0);
gl.enableVertexAttribArray(coords);
var colorsLocation = gl.getAttribLocation(shaderProgram, "colors");
gl.vertexAttribPointer(colorsLocation, 4, gl.FLOAT, false, Float32Array.BYTES_PER_ELEMENT * 7, Float32Array.BYTES_PER_ELEMENT * 3);
gl.enableVertexAttribArray(colorsLocation);
gl.bindBuffer(gl.ARRAY_BUFFER, null);
var pointSize = gl.getAttribLocation(shaderProgram, "pointSize");
gl.vertexAttrib1f(pointSize, 20);
var perspectiveMatrix = mat4.create();
mat4.perspective(perspectiveMatrix, 1, canvas.width / canvas.height, 0.1, 11);
var perspectiveLoc = gl.getUniformLocation(shaderProgram, "perspectiveMatrix");
gl.uniformMatrix4fv(perspectiveLoc, false, perspectiveMatrix);
mat4.translate(matrix, matrix, [0, 0, -2]);
}
function draw() {
mat4.rotateX(matrix, matrix, -0.007);
mat4.rotateY(matrix, matrix, 0.013);
mat4.rotateZ(matrix, matrix, 0.01);
var transformMatrix = gl.getUniformLocation(shaderProgram, "transformMatrix");
gl.uniformMatrix4fv(transformMatrix, false, matrix);
gl.clear(gl.COLOR_BUFFER_BIT);
gl.drawArrays(gl.TRIANGLES, 0, vertexCount);
requestAnimationFrame(draw);
}
/*
* https://developer.mozilla.org/en-US/docs/Web/API/WebGL_API/Tutorial/Adding_2D_content_to_a_WebGL_context
*/
function getShader(gl, id) {
var shaderScript, theSource, currentChild, shader;
shaderScript = document.getElementById(id);
if (!shaderScript) {
return null;
}
theSource = "";
currentChild = shaderScript.firstChild;
while (currentChild) {
if (currentChild.nodeType == currentChild.TEXT_NODE) {
theSource += currentChild.textContent;
}
currentChild = currentChild.nextSibling;
}
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 {
// Unknown shader type
return null;
}
gl.shaderSource(shader, theSource);
// Compile the shader program
gl.compileShader(shader);
// See if it compiled successfully
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
alert("An error occurred compiling the shaders: " + gl.getShaderInfoLog(shader));
return null;
}
return shader;
}