一、webGL简介
什么是webGL
webgl是一种3D绘图协议,衍生于 OpenGL ES2.0,可以结合 Html5 和 JavaScript 在网页上绘制和渲染二/三维图形。
WebGL api 提供三维绘图的方式
图形的绘制主要通过 WebGLRenderingContext 接口完成
WebGL的优势
内嵌在浏览器中,不需要安装任何插件即可运⾏;
只需要⼀个⽂本编辑器和浏览器,就可以编写三维图形程序;
学习和使用比较简单
webgl开源框架
1.Three.js:JavaScript 3D WebGL库
2.Babylon.js:Web3D图形引擎
3.KickJS:Web的开源图形和游戏引擎
4.ClayGL:构建可扩展的Web3D应⽤程序
5.PlayCanvas:网络游戏和3D图形引擎
6.WebGLStudio.js和Litescene.js:开源Web 3D图形编辑器和创建器
7.Luma:Uber的3D WebGL可视化库
8.A-Frame是用于构建VR(虚拟现实)体验的Web框架
二、webGL入门知识
2.1 清空绘图区颜色
- gl.clearColor(r,g,b,a) :指定清空绘图区的颜⾊,接收四个参数(取值区间为 0.0~1.0)
- gl.clear(gl.COLOR_BUFFER_BIT) :使用之前指定的颜色,清空绘图区
- gl.clear 需要和 gl.clearColor 提到的函数搭配使用
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<canvas id="canvas" width="400" height="400">
此浏览器不支持canvas
</canvas>
</body>
</html>
<script>
const ctx = document.getElementById('canvas')
const gl = ctx.getContext('webgl')
// 指定将要用来清空绘图区的颜色 清空颜色缓存
// gl.clearColor(r,g,b,a) 指定清空 <canvas> 的颜⾊,接收四个参数(取值区间为 0.0~1.0)
gl.clearColor(1.0,0.0,0.0,1.0) // red 1.0 green 0.0 blue 0.0 alpha 1.0
// 使用之前指定的颜色,清空绘图区
gl.clear(gl.COLOR_BUFFER_BIT)
</script>
2.2 webGL三维坐标
坐标系概览
绘图区域
2.3 学习使用attribute变量
attribute 变量只能在顶点着色器中使用,不能在片元着色器中使用
变量声明方法如下:
获取attribute变量
给attribute变量赋值
改变顶点位置案例
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script src="../lib/index.js"></script>
</head>
<body>
<canvas id="canvas" width="400" height="400">
此浏览器不支持canvas
</canvas>
</body>
</html>
<script>
const ctx = document.getElementById('canvas')
const gl = ctx.getContext('webgl')
// 创建着色器源码
const VERTEX_SHADER_SOURCE = `
// 只传递顶点数据
attribute vec4 aPosition;
void main() {
gl_Position = aPosition; // vec4(0.0,0.0,0.0,1.0)
gl_PointSize = 30.0;
}
`; // 顶点着色器
const FRAGMENT_SHADER_SOURCE = `
void main() {
gl_FragColor = vec4(1.0,0.0,0.0,1.0);
}
`; // 片元着色器
const program = initShader(gl, VERTEX_SHADER_SOURCE, FRAGMENT_SHADER_SOURCE)
const aPosition = gl.getAttribLocation(program, 'aPosition');
// gl.vertexAttrib4f(aPosition, 0.5,0.5,0.0,1.0)
// gl.vertexAttrib3f(aPosition, 0.5,0.5,0.0)
// gl.vertexAttrib2f(aPosition, 0.5,0.5)
let x = 0;
setInterval(() => {
x += 0.1;
if (x > 1.0) {
x = 0;
}
// 只改变x值
gl.vertexAttrib1f(aPosition, x)
gl.drawArrays(gl.POINTS, 0, 1);
}, 200)
function initShader(gl, VERTEX_SHADER_SOURCE, FRAGMENT_SHADER_SOURCE) {
const vertexShader = gl.createShader(gl.VERTEX_SHADER);
const fragmentShader = gl.createShader(gl.FRAGMENT_SHADER);
gl.shaderSource(vertexShader, VERTEX_SHADER_SOURCE) // 指定顶点着色器的源码
gl.shaderSource(fragmentShader, FRAGMENT_SHADER_SOURCE) // 指定片元着色器的源码
// 编译着色器
gl.compileShader(vertexShader)
gl.compileShader(fragmentShader)
// 创建一个程序对象
const program = gl.createProgram();
gl.attachShader(program, vertexShader)
gl.attachShader(program, fragmentShader)
gl.linkProgram(program)
gl.useProgram(program)
return program;
}
</script>
流程
2.4 学习使用uniform
使用 uniform 变量
添加 uniform 变量,设置到颜色上
获取 uniform 变量存储地址
给uniform 变量赋值
设置精度
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script src="../lib/index.js"></script>
<style>
* {
margin: 0;
padding: 0;
}
canvas{
margin: 50px auto 0;
display: block;
background: yellow;
}
</style>
</head>
<body>
<canvas id="canvas" width="400" height="400">
此浏览器不支持canvas
</canvas>
</body>
</html>
<script>
const ctx = document.getElementById('canvas')
const gl = ctx.getContext('webgl')
// 创建着色器源码
const VERTEX_SHADER_SOURCE = `
uniform vec4 uPosition;
// 只传递顶点数据
attribute vec4 aPosition;
void main() {
gl_Position = aPosition; // vec4(0.0,0.0,0.0,1.0)
gl_PointSize = 10.0;
}
`; // 顶点着色器
// 顶点着色器需要指定精度,如下指定精度为中级精度
const FRAGMENT_SHADER_SOURCE = `
precision mediump float;
uniform vec2 uColor;
void main() {
gl_FragColor = vec4(uColor.r, uColor.g, 0.0,1.0); // vec4
}
`; // 片元着色器
const program = initShader(gl, VERTEX_SHADER_SOURCE, FRAGMENT_SHADER_SOURCE)
const aPosition = gl.getAttribLocation(program, 'aPosition');
const uColor = gl.getUniformLocation(program, 'uColor')
const points = []
ctx.onclick = function(ev) {
// 坐标
const x = ev.clientX
const y = ev.clientY
const domPosition = ev.target.getBoundingClientRect();
const domx = x - domPosition.left
const domy = y - domPosition.top;
// 当前画布宽度的一半
const halfWidth = ctx.offsetWidth / 2
// 当前画布高度的一半
const halfHeight = ctx.offsetHeight / 2
const clickX = (domx - halfWidth) / halfWidth
const clickY = (halfHeight - domy) / halfHeight
points.push({
clickX, clickY
})
for (let i = 0; i < points.length; i++) {
gl.vertexAttrib2f(aPosition, points[i].clickX, points[i].clickY)
gl.uniform2f(uColor, points[i].clickX, points[i].clickY)
gl.drawArrays(gl.POINTS, 0, 1);
}
}
</script>
流程
三、图形绘制与变换
3.1绘制多个点
3.1.1什么是缓冲区对象
缓冲区对象是WebGL系统中的一块内存区域,可以一次性地向缓冲区对象中填充大量的顶点数据,然后将这些数据保存在其中,供顶点着色器使用。
3.1.2创建顶点数据
3.1.3 类型化数组
3.1.4创建缓冲区对象
3.1.5 gl.bindBuffer(target, buffer)
buffer: 已经创建好的缓冲区对象
target:可以是如下两种
gl.ARRAY_BUFFER: 表示缓冲区存储的是顶点的数据
gl.ELEMENT_ARRAY_BUFFER: 表示缓冲区存储的是顶点的索引值
3.1.6 gl.bufferData(target, data, type)
target: 类型同 gl.bindBuffer 中的 target
data: 写⼊缓冲区的顶点数据,如程序中的 points
type: 表示如何使⽤缓冲区对象中的数据,分为以下⼏类
3.1.7 gl,vertexAttribPointer(location, size, type, normalized, stride, offset) 将缓冲区对象分配给一个attribute变量
location: attribute 变量的存储位置
size: 指定每个顶点所使⽤数据的个数
type: 指定数据格式
normalized: 表示是否将数据归⼀化到 [0, 1] [-1, 1] 这个区间
stride:两个相邻顶点之间的字节数
offset:数据偏移量
3.1.8 gl.enableVertexAttribArray(location) 开启attribute变量
3.1.9 绘制多点案例
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script src="../lib/index.js"></script>
<style>
* {
margin: 0;
padding: 0;
}
canvas{
margin: 50px auto 0;
display: block;
background: yellow;
}
</style>
</head>
<body>
<canvas id="canvas" width="400" height="400">
此浏览器不支持canvas
</canvas>
</body>
</html>
<script>
const ctx = document.getElementById('canvas')
const gl = ctx.getContext('webgl')
// 创建着色器源码
const VERTEX_SHADER_SOURCE = `
// 只传递顶点数据
attribute vec4 aPosition;
void main() {
gl_Position = aPosition; // vec4(0.0,0.0,0.0,1.0)
gl_PointSize = 10.0;
}
`; // 顶点着色器
const FRAGMENT_SHADER_SOURCE = `
void main() {
gl_FragColor = vec4(1.0,0.0,0.0,1.0);
}
`; // 片元着色器
const program = initShader(gl, VERTEX_SHADER_SOURCE, FRAGMENT_SHADER_SOURCE)
const aPosition = gl.getAttribLocation(program, 'aPosition');
const points = new Float32Array([
-0.5, -0.5,
0.5, -0.5,
0.0, 0.5,
])
// 创建缓冲区对象
const buffer = gl.createBuffer();
// gl.ARRAY_BUFFER 缓冲区存储的是顶点数据
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
// 将数据写入缓冲区对象
gl.bufferData(gl.ARRAY_BUFFER, points, gl.STATIC_DRAW);// 写入一次,多次绘制
// 将缓冲区对象分配给一个attribute变量
gl.vertexAttribPointer(aPosition, 2, gl.FLOAT, false, 0, 0);
// 开启attribute变量
gl.enableVertexAttribArray(aPosition)
// gl.vertexAttrib2f(aPosition, 0.0, 0.0)
// 绘制什么图形,从哪个顶点开始绘制,需要绘制几个顶点
gl.drawArrays(gl.POINTS, 0, 3);
</script>
3.1.10 缓冲区使用流程
3.1.11 缓冲区执行过程
3.2 数据偏移
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script src="../lib/index.js"></script>
<style>
* {
margin: 0;
padding: 0;
}
canvas{
margin: 50px auto 0;
display: block;
background: yellow;
}
</style>
</head>
<body>
<canvas id="canvas" width="400" height="400">
此浏览器不支持canvas
</canvas>
</body>
</html>
<script>
const ctx = document.getElementById('canvas')
const gl = ctx.getContext('webgl')
// 创建着色器源码
const VERTEX_SHADER_SOURCE = `
attribute vec4 aPosition;
attribute float aPointSize;
void main() {
gl_Position = aPosition;
gl_PointSize = aPointSize;
}
`; // 顶点着色器
const FRAGMENT_SHADER_SOURCE = `
void main() {
gl_FragColor = vec4(1.0,0.0,0.0,1.0);
}
`; // 片元着色器
const program = initShader(gl, VERTEX_SHADER_SOURCE, FRAGMENT_SHADER_SOURCE)
const aPosition = gl.getAttribLocation(program, 'aPosition');
const aPointSize = gl.getAttribLocation(program, 'aPointSize');
const points = new Float32Array([
-0.5, -0.5, 10.0, // 10.0
0.5, -0.5, 20.0, // 20.0
0.0, 0.5, 30.0, // 30.0
])
const buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, points, gl.STATIC_DRAW);
const BYTES = points.BYTES_PER_ELEMENT;
// 两个数据之间的字节数是3。偏移0个字节取值。
gl.vertexAttribPointer(aPosition, 2, gl.FLOAT, false, BYTES * 3, 0);
gl.enableVertexAttribArray(aPosition)
// 两个数据之间的字节数是3。偏移2个字节取值。
gl.vertexAttribPointer(aPointSize, 1, gl.FLOAT, false, BYTES * 3, BYTES * 2);
gl.enableVertexAttribArray(aPointSize)
gl.drawArrays(gl.POINTS, 0, 3);
</script>
3.3 多图形绘制
gl.drawArrays(mode, first, count)的mode参数其实十分强大,可以按照不同的规则绘制不同的图形,可直接绘制的图形有七种,这七种图形是绘制其它各种复杂图形的基础。
3.4 图形平移
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script src="../lib/index.js"></script>
<style>
* {
margin: 0;
padding: 0;
}
canvas{
margin: 50px auto 0;
display: block;
background: yellow;
}
</style>
</head>
<body>
<canvas id="canvas" width="400" height="400">
此浏览器不支持canvas
</canvas>
</body>
</html>
<script>
const ctx = document.getElementById('canvas')
const gl = ctx.getContext('webgl')
// 创建着色器源码
const VERTEX_SHADER_SOURCE = `
attribute vec4 aPosition;
attribute float aTranslate;
void main() {
gl_Position = vec4(aPosition.x + aTranslate, aPosition.y, aPosition.z, 1.0);
gl_PointSize = 10.0;
}
`; // 顶点着色器
const FRAGMENT_SHADER_SOURCE = `
void main() {
gl_FragColor = vec4(1.0,0.0,0.0,1.0);
}
`; // 片元着色器
const program = initShader(gl, VERTEX_SHADER_SOURCE, FRAGMENT_SHADER_SOURCE)
const aPosition = gl.getAttribLocation(program, 'aPosition');
const aTranslate = gl.getAttribLocation(program, 'aTranslate');
const points = new Float32Array([
-0.5, -0.5,
0.5, -0.5,
0.0, 0.5,
])
const buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, points, gl.STATIC_DRAW);
gl.vertexAttribPointer(aPosition, 2, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(aPosition)
let x = -1;
setInterval(() => {
x += 0.01;
if (x > 1) {
x = -1;
}
gl.vertexAttrib1f(aTranslate, x);
gl.drawArrays(gl.TRIANGLES, 0, 3);
}, 60)
</script>
3.5 图形缩放
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script src="../lib/index.js"></script>
<style>
* {
margin: 0;
padding: 0;
}
canvas{
margin: 50px auto 0;
display: block;
background: yellow;
}
</style>
</head>
<body>
<canvas id="canvas" width="400" height="400">
此浏览器不支持canvas
</canvas>
</body>
</html>
<script>
const ctx = document.getElementById('canvas')
const gl = ctx.getContext('webgl')
// 创建着色器源码
const VERTEX_SHADER_SOURCE = `
attribute vec4 aPosition;
attribute float aScale;
void main() {
gl_Position = vec4(aPosition.x * aScale, aPosition.y * aScale, aPosition.z * aScale, 1.0);
gl_PointSize = 10.0;
}
`; // 顶点着色器
const FRAGMENT_SHADER_SOURCE = `
void main() {
gl_FragColor = vec4(1.0,0.0,0.0,1.0);
}
`; // 片元着色器
const program = initShader(gl, VERTEX_SHADER_SOURCE, FRAGMENT_SHADER_SOURCE)
const aPosition = gl.getAttribLocation(program, 'aPosition');
const aScale = gl.getAttribLocation(program, 'aScale');
const points = new Float32Array([
-0.5, -0.5,
0.5, -0.5,
0.0, 0.5,
])
const buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, points, gl.STATIC_DRAW);
gl.vertexAttribPointer(aPosition, 2, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(aPosition)
let x = 1;
setInterval(() => {
x += 0.1;
if (x > 2) {
x = 1;
}
gl.vertexAttrib1f(aScale, x);
gl.drawArrays(gl.TRIANGLES, 0, 3);
}, 60)
</script>
3.6 图形平移-平移矩阵
// 平移矩阵
function getTranslateMatrix(x = 0,y = 0,z = 0) {
return new Float32Array([
1.0,0.0,0.0,0.0,
0.0,1.0,0.0,0.0,
0.0,0.0,1.0,0.0,
x ,y ,z , 1,
])
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script src="../lib/index.js"></script>
<style>
* {
margin: 0;
padding: 0;
}
canvas{
margin: 50px auto 0;
display: block;
background: yellow;
}
</style>
</head>
<body>
<canvas id="canvas" width="400" height="400">
此浏览器不支持canvas
</canvas>
</body>
</html>
<script>
const ctx = document.getElementById('canvas')
const gl = ctx.getContext('webgl')
// 创建着色器源码
const VERTEX_SHADER_SOURCE = `
attribute vec4 aPosition;
uniform mat4 mat;
void main() {
gl_Position = mat * aPosition;
gl_PointSize = 10.0;
}
`; // 顶点着色器
const FRAGMENT_SHADER_SOURCE = `
void main() {
gl_FragColor = vec4(1.0,0.0,0.0,1.0);
}
`; // 片元着色器
const program = initShader(gl, VERTEX_SHADER_SOURCE, FRAGMENT_SHADER_SOURCE)
const aPosition = gl.getAttribLocation(program, 'aPosition');
const mat = gl.getUniformLocation(program, 'mat');
const points = new Float32Array([
-0.5, -0.5,
0.5, -0.5,
0.0, 0.5,
])
const buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, points, gl.STATIC_DRAW);
gl.vertexAttribPointer(aPosition, 2, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(aPosition)
let x = -1;
function animation() {
x += 0.01;
if (x > 1) {
x = -1;
}
// getTranslateMatrix的x和y参数是x轴和y轴的偏移量
const matrix = getTranslateMatrix(x,x);
// gl.vertexAttrib1f(aTranslate, x);
gl.uniformMatrix4fv(mat, false, matrix);
gl.drawArrays(gl.TRIANGLES, 0, 3);
requestAnimationFrame(animation);
}
animation()
</script>
平移矩阵函数推导过程
3.7缩放矩阵-图形缩放
// 缩放矩阵
function getScaleMatrix(x = 1,y = 1,z = 1) {
return new Float32Array([
x ,0.0,0.0,0.0,
0.0,y ,0.0,0.0,
0.0,0.0,z ,0.0,
0.0,0.0,0.0, 1,
])
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script src="../lib/index.js"></script>
<style>
* {
margin: 0;
padding: 0;
}
canvas{
margin: 50px auto 0;
display: block;
background: yellow;
}
</style>
</head>
<body>
<canvas id="canvas" width="400" height="400">
此浏览器不支持canvas
</canvas>
</body>
</html>
<script>
// 矩阵在数学中是按行,在webgl中是按列的,所以把数学中的矩阵沿着对角线做翻转
const ctx = document.getElementById('canvas')
const gl = ctx.getContext('webgl')
// 创建着色器源码
// uniform对所有变量生效
const VERTEX_SHADER_SOURCE = `
attribute vec4 aPosition;
uniform mat4 mat;
void main() {
gl_Position = mat * aPosition;
gl_PointSize = 10.0;
}
`; // 顶点着色器
const FRAGMENT_SHADER_SOURCE = `
void main() {
gl_FragColor = vec4(1.0,0.0,0.0,1.0);
}
`; // 片元着色器
const program = initShader(gl, VERTEX_SHADER_SOURCE, FRAGMENT_SHADER_SOURCE)
const aPosition = gl.getAttribLocation(program, 'aPosition');
const mat = gl.getUniformLocation(program, 'mat');
const points = new Float32Array([
-0.5, -0.5,
0.5, -0.5,
0.0, 0.5,
])
const buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, points, gl.STATIC_DRAW);
gl.vertexAttribPointer(aPosition, 2, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(aPosition)
let x = 0.1;
function animation() {
x += 0.01;
if (x > 1.5) {
x = 0.1;
}
// getScaleMatrix 的参数 x,y是x轴坐标和y轴坐标分别放大多少倍数;
const matrix = getScaleMatrix(x,x);
// gl.vertexAttrib1f(aTranslate, x);
gl.uniformMatrix4fv(mat, false, matrix);
gl.drawArrays(gl.TRIANGLES, 0, 3);
requestAnimationFrame(animation);
}
animation()
</script>
缩放矩阵推导过程
3.8 旋转矩阵
// 绕z轴旋转的旋转矩阵
function getRotateMatrix(deg) {
return new Float32Array([
Math.cos(deg) ,Math.sin(deg) ,0.0,0.0,
-Math.sin(deg) ,Math.cos(deg) ,0.0,0.0,
0.0, 0.0, 1.0,0.0,
0.0, 0.0, 0.0, 1,
])
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script src="../lib/index.js"></script>
<style>
* {
margin: 0;
padding: 0;
}
canvas{
margin: 50px auto 0;
display: block;
background: yellow;
}
</style>
</head>
<body>
<canvas id="canvas" width="400" height="400">
此浏览器不支持canvas
</canvas>
</body>
</html>
<script>
// 矩阵在数学中是按行,在webgl中是按列的,所以把数学中的矩阵沿着对角线做翻转
const ctx = document.getElementById('canvas')
const gl = ctx.getContext('webgl')
// 创建着色器源码
// uniform对所有变量生效
const VERTEX_SHADER_SOURCE = `
attribute vec4 aPosition;
uniform mat4 mat;
void main() {
gl_Position = mat * aPosition;
gl_PointSize = 10.0;
}
`; // 顶点着色器
const FRAGMENT_SHADER_SOURCE = `
void main() {
gl_FragColor = vec4(1.0,0.0,0.0,1.0);
}
`; // 片元着色器
const program = initShader(gl, VERTEX_SHADER_SOURCE, FRAGMENT_SHADER_SOURCE)
const aPosition = gl.getAttribLocation(program, 'aPosition');
const mat = gl.getUniformLocation(program, 'mat');
const points = new Float32Array([
-0.5, -0.5,
0.5, -0.5,
0.0, 0.5,
])
const buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, points, gl.STATIC_DRAW);
gl.vertexAttribPointer(aPosition, 2, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(aPosition)
let x = 0.1;
function animation() {
x += 0.01;
if (x > 1.5) {
x = 0.1;
}
// getScaleMatrix 的参数 x,y是x轴坐标和y轴坐标分别放大多少倍数;
const matrix = getScaleMatrix(x,x);
// gl.vertexAttrib1f(aTranslate, x);
gl.uniformMatrix4fv(mat, false, matrix);
gl.drawArrays(gl.TRIANGLES, 0, 3);
requestAnimationFrame(animation);
}
animation()
</script>
旋转矩阵推导过程
3.9 复合图形变换-矩阵组合
// 矩阵复合函数
function mixMatrix(A, B) {
const result = new Float32Array(16);
for (let i = 0; i < 4; i++) {
result[i] = A[i] * B[0] + A[i + 4] * B[1] + A[i + 8] * B[2] + A[i + 12] * B[3]
result[i + 4] = A[i] * B[4] + A[i + 4] * B[5] + A[i + 8] * B[6] + A[i + 12] * B[7]
result[i + 8] = A[i] * B[8] + A[i + 4] * B[9] + A[i + 8] * B[10] + A[i + 12] * B[11]
result[i + 12] = A[i] * B[12] + A[i + 4] * B[13] + A[i + 8] * B[14] + A[i + 12] * B[15]
}
return result;
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script src="../lib/index.js"></script>
<style>
* {
margin: 0;
padding: 0;
}
canvas{
margin: 50px auto 0;
display: block;
background: yellow;
}
</style>
</head>
<body>
<canvas id="canvas" width="400" height="400">
此浏览器不支持canvas
</canvas>
</body>
</html>
<script>
const ctx = document.getElementById('canvas')
const gl = ctx.getContext('webgl')
// 创建着色器源码
const VERTEX_SHADER_SOURCE = `
attribute vec4 aPosition;
uniform mat4 mat;
void main() {
gl_Position = mat * aPosition;
}
`; // 顶点着色器
const FRAGMENT_SHADER_SOURCE = `
void main() {
gl_FragColor = vec4(1.0,0.0,0.0,1.0);
}
`; // 片元着色器
const program = initShader(gl, VERTEX_SHADER_SOURCE, FRAGMENT_SHADER_SOURCE)
const aPosition = gl.getAttribLocation(program, 'aPosition');
const mat = gl.getUniformLocation(program, 'mat');
const points = new Float32Array([
-0.5, -0.5,
0.5, -0.5,
0.0, 0.5,
])
const buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, points, gl.STATIC_DRAW);
gl.vertexAttribPointer(aPosition, 2, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(aPosition)
let deg = 0;
let translateX = -1;
let scaleX = 0.1;
function animation() {
deg += 0.01;
translateX += 0.01;
scaleX += 0.01;
if (translateX > 1) {
translateX = -1;
}
if (scaleX > 1.5) {
scaleX = 0.1;
}
const translate = getTranslateMatrix(translateX);
const scale = getScaleMatrix(scaleX);
const rotate = getRotateMatrix(deg);
const matrix = mixMatrix(mixMatrix(translate, scale), rotate)
// gl.vertexAttrib1f(aTranslate, x);
gl.uniformMatrix4fv(mat, false, matrix);
gl.drawArrays(gl.TRIANGLES, 0, 3);
requestAnimationFrame(animation);
}
animation()
</script>