矩阵库

• 手写矩阵，其实很麻烦，可以将其模块化
• 市面上已经有许多开源的矩阵库
  • 比如《WebGL 编程指南》里的 cuon-matrix.js
  • three.js 的 Matrix3 和 Matrix4 对象

three.js的 Matrix4 对象的用法

1 ）核心代码

• 1.引入Matrix4对象

  import { Matrix4 } from 'https://unpkg.com/three/build/three.module.js';
  

• 2.实例化矩阵对象，在其中写入旋转信息

  const matrix = new Matrix4()
  matrix.makeRotationZ(Math.PI/6)
  

• 3.基于matrix 对象的elements 属性，修改uniform 变量

  const u_Matrix=gl.getUniformLocation(gl.program,'u_Matrix')
  gl.uniformMatrix4fv(u_Matrix,false,matrix.elements)
  

2 ）完整代码

<canvas id="canvas"></canvas>
<script id="vertexShader" type="x-shader/x-vertex">attribute vec4 a_Position;// 列主序uniform mat4 u_Matrix;void main() {gl_Position = u_Matrix * a_Position;}
</script>
<script id="fragmentShader" type="x-shader/x-fragment">void main() {gl_FragColor = vec4(1.0, 1.0, 0.0, 1.0);}
</script>
<script type="module">import { initShaders } from './utils.js';import { Matrix4 } from 'https://unpkg.com/three/build/three.module.js';const canvas = document.getElementById('canvas');canvas.width = window.innerWidth;canvas.height = window.innerHeight;const gl = canvas.getContext('webgl');const vsSource = document.getElementById('vertexShader').innerText;const fsSource = document.getElementById('fragmentShader').innerText;initShaders(gl, vsSource, fsSource);const vertices = new Float32Array([0.0, 0.1,-0.1, -0.1,0.1, -0.1]);const vertexBuffer = gl.createBuffer();gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW);const a_Position = gl.getAttribLocation(gl.program, 'a_Position');gl.vertexAttribPointer(a_Position, 2, gl.FLOAT, false, 0, 0);gl.enableVertexAttribArray(a_Position);const u_Matrix = gl.getUniformLocation(gl.program, 'u_Matrix');let angle = 0.1;const m4 = new Matrix4();m4.makeRotationZ(angle);gl.uniformMatrix4fv(u_Matrix, false, m4.elements);gl.clearColor(0.0, 0.0, 0.0, 1.0);gl.clear(gl.COLOR_BUFFER_BIT);gl.drawArrays(gl.TRIANGLES, 0, 3);!(function animate() {angle += 0.05;m4.makeRotationZ(angle);gl.uniformMatrix4fv(u_Matrix, false, m4.elements);gl.clear(gl.COLOR_BUFFER_BIT);gl.drawArrays(gl.TRIANGLES, 0, 3);requestAnimationFrame(animate);})()
</script>