代码1：
1 <!DOCTYPE html> 2 <html lang="en"> 3 <head> 4 <meta charset="UTF-8"> 5 <title>WebGl 旋转（矩阵变换）</title> 6 </head> 7 <body> 8 <canvas id="myCanvas" width="500" height="300" style="border: 1px solid red"></canvas> 9 </body> 10 <script> 11 12 window.onload = function () { 13 14 //第1步 - 准备Canvas和获取WebGL的渲染上下文 15 var canvas = document.getElementById(\'myCanvas\'), 16 gl = canvas.getContext(\'webgl\'); 17 18 //第2步 - 定义几何并将其存储在缓冲区对象 19 var vertices = [ 20 -0.5,0.5,0.0, 21 0.0,0.5,0.0, 22 -0.25,0.25,0.0, 23 ], 24 colors = [ 25 0,0,1, 26 1,0,0, 27 0,1,0,], 28 indices =[0,1,2]; 29 30 var vertex_buffer = gl.createBuffer(); 31 gl.bindBuffer(gl.ARRAY_BUFFER, vertex_buffer); 32 gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW); 33 34 var color_buffer = gl.createBuffer (); 35 gl.bindBuffer(gl.ARRAY_BUFFER, color_buffer); 36 gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW); 37 38 var index_buffer = gl.createBuffer(); 39 gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, index_buffer); 40 gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(indices), gl.STATIC_DRAW); 41 42 //第3步 - 创建和编译着色器程序 43 var vertCode = 44 \'attribute vec3 coordinates;\' + 45 \'uniform mat4 rotate;\'+ 46 \'attribute vec3 color;\'+ 47 \'varying vec3 vColor;\'+ 48 \'void main(void) {\' + 49 \' gl_Position = rotate*vec4(coordinates,1.0);\' + 50 \'vColor = color;\'+ 51 \'}\'; 52 53 var fragCode = 54 \'precision mediump float;\'+ 55 \'varying vec3 vColor;\'+ 56 \'void main(void) {\' + 57 \' gl_FragColor = vec4(vColor, 1);\' + 58 \'}\'; 59 60 var vertShader = gl.createShader(gl.VERTEX_SHADER); 61 var fragShader = gl.createShader(gl.FRAGMENT_SHADER); 62 gl.shaderSource(vertShader, vertCode); 63 gl.shaderSource(fragShader, fragCode); 64 gl.compileShader(vertShader); 65 gl.compileShader(fragShader); 66 var shaderProgram = gl.createProgram(); 67 gl.attachShader(shaderProgram, vertShader); 68 gl.attachShader(shaderProgram, fragShader); 69 gl.linkProgram(shaderProgram); 70 gl.useProgram(shaderProgram); 71 72 73 //第4步 - 关联着色器程序到缓冲区对象 74 75 76 gl.bindBuffer(gl.ARRAY_BUFFER, vertex_buffer); 77 var coord = gl.getAttribLocation(shaderProgram, \'coordinates\'); 78 gl.vertexAttribPointer(coord, 3, gl.FLOAT, false, 0, 0); 79 gl.enableVertexAttribArray(coord); 80 81 gl.bindBuffer(gl.ARRAY_BUFFER, color_buffer); 82 var color = gl.getAttribLocation(shaderProgram, "color"); 83 gl.vertexAttribPointer(color, 3, gl.FLOAT, false,0,0) ; //color 84 gl.enableVertexAttribArray(color); 85 86 //绕着Z轴旋转 87 var init_angle = 0.0;//初始角度 88 var angle_step = 1;//旋转步伐 89 var current_angle = init_angle; 90 var radian = Math.PI * (current_angle % 360) / 180.0; 91 var cosB = Math.cos(radian); 92 var sinB = Math.sin(radian); 93 var xformMatrix = new Float32Array([ 94 cosB, sinB, 0.0, 0.0, 95 -sinB, cosB, 0.0, 0.0, 96 0.0, 0.0, 1.0, 0.0, 97 0.0, 0.0, 0.0, 1.0 98 ]); 99 var rotate = gl.getUniformLocation(shaderProgram, "rotate"); 100 gl.uniformMatrix4fv(rotate, false, xformMatrix); 101 102 //第5步 - 绘制所需的对象 103 setInterval(function () { 104 radian = Math.PI * (current_angle % 360) / 180.0; 105 cosB = Math.cos(radian); 106 sinB = Math.sin(radian); 107 xformMatrix = new Float32Array([ 108 cosB, sinB, 0.0, 0.0, 109 -sinB, cosB, 0.0, 0.0, 110 0.0, 0.0, 1.0, 0.0, 111 0.0, 0.0, 0.0, 1.0 112 ]); 113 gl.uniformMatrix4fv(rotate, false, xformMatrix); 114 115 gl.enable(gl.DEPTH_TEST); 116 gl.depthFunc(gl.LEQUAL); 117 gl.clearColor(0.5, 0.5, 0.5, 0.9); 118 gl.clearDepth(1.0); 119 gl.viewport(0.0, 0.0, canvas.width, canvas.height); 120 gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); 121 gl.drawElements(gl.TRIANGLES, indices.length, gl.UNSIGNED_SHORT, 0); 122 123 124 //当前角度 125 current_angle = current_angle + angle_step; 126 127 },10); 128 129 130 131 132 133 } 134 135 </script> 136 </html>
代码2：
1 <!DOCTYPE html> 2 <html lang="en"> 3 <head> 4 <meta charset="UTF-8"> 5 <title>WebGl 旋转（矩阵变换）</title> 6 </head> 7 <body> 8 <canvas id="myCanvas" width="500" height="300" style="border: 1px solid red"></canvas> 9 </body> 10 <script> 11 12 window.onload = function () { 13 14 //第1步 - 准备Canvas和获取WebGL的渲染上下文 15 var canvas = document.getElementById(\'myCanvas\'), 16 gl = canvas.getContext(\'webgl\'); 17 18 //第2步 - 定义几何并将其存储在缓冲区对象 19 var vertices = [ 20 -0.5,0.5,0.0, 21 0.0,0.5,0.0, 22 -0.25,0.25,0.0, 23 ], 24 colors = [ 25 0,0,1, 26 1,0,0, 27 0,1,0,], 28 indices =[0,1,2]; 29 30 var vertex_buffer = gl.createBuffer(); 31 gl.bindBuffer(gl.ARRAY_BUFFER, vertex_buffer); 32 gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW); 33 34 var color_buffer = gl.createBuffer (); 35 gl.bindBuffer(gl.ARRAY_BUFFER, color_buffer); 36 gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW); 37 38 var index_buffer = gl.createBuffer(); 39 gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, index_buffer); 40 gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(indices), gl.STATIC_DRAW); 41 42 //第3步 - 创建和编译着色器程序 43 var vertCode = 44 \'attribute vec3 coordinates;\' + 45 \'uniform mat4 Pmatrix;\'+ 46 \'uniform mat4 Vmatrix;\'+ 47 \'uniform mat4 Mmatrix;\'+ 48 \'attribute vec3 color;\'+ 49 \'varying vec3 vColor;\'+ 50 \'void main(void) {\' + 51 \' gl_Position = Pmatrix*Vmatrix*Mmatrix*vec4(coordinates,1.0);\' + 52 \'vColor = color;\'+ 53 \'}\'; 54 55 var fragCode = 56 \'precision mediump float;\'+ 57 \'varying vec3 vColor;\'+ 58 \'void main(void) {\' + 59 \' gl_FragColor = vec4(vColor, 1);\' + 60 \'}\'; 61 62 var vertShader = gl.createShader(gl.VERTEX_SHADER); 63 var fragShader = gl.createShader(gl.FRAGMENT_SHADER); 64 gl.shaderSource(vertShader, vertCode); 65 gl.shaderSource(fragShader, fragCode); 66 gl.compileShader(vertShader); 67 gl.compileShader(fragShader); 68 var shaderProgram = gl.createProgram(); 69 gl.attachShader(shaderProgram, vertShader); 70 gl.attachShader(shaderProgram, fragShader); 71 gl.linkProgram(shaderProgram); 72 gl.useProgram(shaderProgram); 73 74 75 //第4步 - 关联着色器程序到缓冲区对象 76 var Pmatrix = gl.getUniformLocation(shaderProgram, "Pmatrix"); 77 var Vmatrix = gl.getUniformLocation(shaderProgram, "Vmatrix"); 78 var Mmatrix = gl.getUniformLocation(shaderProgram, "Mmatrix"); 79 80 gl.bindBuffer(gl.ARRAY_BUFFER, vertex_buffer); 81 var coord = gl.getAttribLocation(shaderProgram, \'coordinates\'); 82 gl.vertexAttribPointer(coord, 3, gl.FLOAT, false, 0, 0); 83 gl.enableVertexAttribArray(coord); 84 85 gl.bindBuffer(gl.ARRAY_BUFFER, color_buffer); 86 var color = gl.getAttribLocation(shaderProgram, "color"); 87 gl.vertexAttribPointer(color, 3, gl.FLOAT, false,0,0) ; //color 88 gl.enableVertexAttribArray(color); 89 90 91 // 92 var proj_matrix = get_projection(40, canvas.width/canvas.height, 1, 100); 93 var mov_matrix = [1,0,0,0, 0,1,0,0, 0,0,1,0, 0,0,0,1]; 94 var view_matrix = [1,0,0,0, 0,1,0,0, 0,0,1,0, 0,0,0,1]; 95 96 //translating z 97 view_matrix[14] = view_matrix[14]-2; //zoom 98 99 //第5步 - 绘制所需的对象 100 var time_old = 0; 101 var animate = function(time) { 102 var dt = time-time_old; 103 rotateZ(mov_matrix, dt*0.002); 104 time_old = time; 105 106 gl.enable(gl.DEPTH_TEST); 107 gl.depthFunc(gl.LEQUAL); 108 gl.clearColor(0.5, 0.5, 0.5, 0.9); 109 gl.clearDepth(1.0); 110 gl.viewport(0.0, 0.0, canvas.width, canvas.height); 111 gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); 112 113 // 将旋转矩阵传输给顶点着色器 114 gl.uniformMatrix4fv(Pmatrix, false, proj_matrix); 115 gl.uniformMatrix4fv(Vmatrix, false, view_matrix); 116 gl.uniformMatrix4fv(Mmatrix, false, mov_matrix); 117 118 gl.drawElements(gl.TRIANGLES, indices.length, gl.UNSIGNED_SHORT, 0); 119 window.requestAnimationFrame(animate); 120 } 121 122 animate(0); 123 124 /*========================= MATRIX ========================= */ 125 126 function get_projection(angle, a, zMin, zMax) { 127 var ang = Math.tan((angle*.5)*Math.PI/180);//angle*.5 128 return [ 129 0.5/ang, 0 , 0, 0, 130 0, 0.5*a/ang, 0, 0, 131 0, 0, -(zMax+zMin)/(zMax-zMin), -1, 132 0, 0, (-2*zMax*zMin)/(zMax-zMin), 0 133 ]; 134 } 135 136 137 138 //z轴旋转 139 function rotateZ(m, angle) { 140 var c = Math.cos(angle); 141 var s = Math.sin(angle); 142 var mv0 = m[0], mv4 = m[4], mv8 = m[8]; 143 144 m[0] = c*m[0]-s*m[1]; 145 m[4] = c*m[4]-s*m[5]; 146 m[8] = c*m[8]-s*m[9]; 147 m[1] = c*m[1]+s*mv0; 148 m[5] = c*m[5]+s*mv4; 149 m[9] = c*m[9]+s*mv8; 150 } 151 152 153 154 155 } 156 157 </script> 158 </html>