代码1：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>WebGl 旋转（矩阵变换）</title>
</head>
<body>
<canvas id="myCanvas" width="500" height="300" style="border: 1px solid red"></canvas>
</body>
<script> window.onload = function () { //第1步 - 准备Canvas和获取WebGL的渲染上下文
var canvas = document.getElementById('myCanvas'),
gl = canvas.getContext('webgl'); //第2步 - 定义几何并将其存储在缓冲区对象
var vertices = [
-0.5,0.5,0.0,
0.0,0.5,0.0,
-0.25,0.25,0.0,
],
colors = [
0,0,1,
1,0,0,
0,1,0,],
indices =[0,1,2]; var vertex_buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, vertex_buffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW); var color_buffer = gl.createBuffer ();
gl.bindBuffer(gl.ARRAY_BUFFER, color_buffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW); var index_buffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, index_buffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(indices), gl.STATIC_DRAW); //第3步 - 创建和编译着色器程序
var vertCode =
'attribute vec3 coordinates;' +
'uniform mat4 rotate;'+
'attribute vec3 color;'+
'varying vec3 vColor;'+
'void main(void) {' +
' gl_Position = rotate*vec4(coordinates,1.0);' +
'vColor = color;'+
'}'; var fragCode =
'precision mediump float;'+
'varying vec3 vColor;'+
'void main(void) {' +
' gl_FragColor = vec4(vColor, 1);' +
'}'; var vertShader = gl.createShader(gl.VERTEX_SHADER);
var fragShader = gl.createShader(gl.FRAGMENT_SHADER);
gl.shaderSource(vertShader, vertCode);
gl.shaderSource(fragShader, fragCode);
gl.compileShader(vertShader);
gl.compileShader(fragShader);
var shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertShader);
gl.attachShader(shaderProgram, fragShader);
gl.linkProgram(shaderProgram);
gl.useProgram(shaderProgram); //第4步 - 关联着色器程序到缓冲区对象 gl.bindBuffer(gl.ARRAY_BUFFER, vertex_buffer);
var coord = gl.getAttribLocation(shaderProgram, 'coordinates');
gl.vertexAttribPointer(coord, 3, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(coord); gl.bindBuffer(gl.ARRAY_BUFFER, color_buffer);
var color = gl.getAttribLocation(shaderProgram, "color");
gl.vertexAttribPointer(color, 3, gl.FLOAT, false,0,0) ; //color
gl.enableVertexAttribArray(color); //绕着Z轴旋转
var init_angle = 0.0;//初始角度
var angle_step = 1;//旋转步伐
var current_angle = init_angle;
var radian = Math.PI * (current_angle % 360) / 180.0;
var cosB = Math.cos(radian);
var sinB = Math.sin(radian);
var xformMatrix = new Float32Array([
cosB, sinB, 0.0, 0.0,
-sinB, cosB, 0.0, 0.0,
0.0, 0.0, 1.0, 0.0,
0.0, 0.0, 0.0, 1.0
]);
var rotate = gl.getUniformLocation(shaderProgram, "rotate");
gl.uniformMatrix4fv(rotate, false, xformMatrix); //第5步 - 绘制所需的对象
setInterval(function () {
radian = Math.PI * (current_angle % 360) / 180.0;
cosB = Math.cos(radian);
sinB = Math.sin(radian);
xformMatrix = new Float32Array([
cosB, sinB, 0.0, 0.0,
-sinB, cosB, 0.0, 0.0,
0.0, 0.0, 1.0, 0.0,
0.0, 0.0, 0.0, 1.0
]);
gl.uniformMatrix4fv(rotate, false, xformMatrix); gl.enable(gl.DEPTH_TEST);
gl.depthFunc(gl.LEQUAL);
gl.clearColor(0.5, 0.5, 0.5, 0.9);
gl.clearDepth(1.0);
gl.viewport(0.0, 0.0, canvas.width, canvas.height);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
gl.drawElements(gl.TRIANGLES, indices.length, gl.UNSIGNED_SHORT, 0); //当前角度
current_angle = current_angle + angle_step; },10); } </script>
</html>
代码2：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>WebGl 旋转（矩阵变换）</title>
</head>
<body>
<canvas id="myCanvas" width="500" height="300" style="border: 1px solid red"></canvas>
</body>
<script> window.onload = function () { //第1步 - 准备Canvas和获取WebGL的渲染上下文
var canvas = document.getElementById('myCanvas'),
gl = canvas.getContext('webgl'); //第2步 - 定义几何并将其存储在缓冲区对象
var vertices = [
-0.5,0.5,0.0,
0.0,0.5,0.0,
-0.25,0.25,0.0,
],
colors = [
0,0,1,
1,0,0,
0,1,0,],
indices =[0,1,2]; var vertex_buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, vertex_buffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW); var color_buffer = gl.createBuffer ();
gl.bindBuffer(gl.ARRAY_BUFFER, color_buffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW); var index_buffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, index_buffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(indices), gl.STATIC_DRAW); //第3步 - 创建和编译着色器程序
var vertCode =
'attribute vec3 coordinates;' +
'uniform mat4 Pmatrix;'+
'uniform mat4 Vmatrix;'+
'uniform mat4 Mmatrix;'+
'attribute vec3 color;'+
'varying vec3 vColor;'+
'void main(void) {' +
' gl_Position = Pmatrix*Vmatrix*Mmatrix*vec4(coordinates,1.0);' +
'vColor = color;'+
'}'; var fragCode =
'precision mediump float;'+
'varying vec3 vColor;'+
'void main(void) {' +
' gl_FragColor = vec4(vColor, 1);' +
'}'; var vertShader = gl.createShader(gl.VERTEX_SHADER);
var fragShader = gl.createShader(gl.FRAGMENT_SHADER);
gl.shaderSource(vertShader, vertCode);
gl.shaderSource(fragShader, fragCode);
gl.compileShader(vertShader);
gl.compileShader(fragShader);
var shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertShader);
gl.attachShader(shaderProgram, fragShader);
gl.linkProgram(shaderProgram);
gl.useProgram(shaderProgram); //第4步 - 关联着色器程序到缓冲区对象
var Pmatrix = gl.getUniformLocation(shaderProgram, "Pmatrix");
var Vmatrix = gl.getUniformLocation(shaderProgram, "Vmatrix");
var Mmatrix = gl.getUniformLocation(shaderProgram, "Mmatrix"); gl.bindBuffer(gl.ARRAY_BUFFER, vertex_buffer);
var coord = gl.getAttribLocation(shaderProgram, 'coordinates');
gl.vertexAttribPointer(coord, 3, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(coord); gl.bindBuffer(gl.ARRAY_BUFFER, color_buffer);
var color = gl.getAttribLocation(shaderProgram, "color");
gl.vertexAttribPointer(color, 3, gl.FLOAT, false,0,0) ; //color
gl.enableVertexAttribArray(color); //
var proj_matrix = get_projection(40, canvas.width/canvas.height, 1, 100);
var mov_matrix = [1,0,0,0, 0,1,0,0, 0,0,1,0, 0,0,0,1];
var view_matrix = [1,0,0,0, 0,1,0,0, 0,0,1,0, 0,0,0,1]; //translating z
view_matrix[14] = view_matrix[14]-2; //zoom //第5步 - 绘制所需的对象
var time_old = 0;
var animate = function(time) {
var dt = time-time_old;
rotateZ(mov_matrix, dt*0.002);
time_old = time; gl.enable(gl.DEPTH_TEST);
gl.depthFunc(gl.LEQUAL);
gl.clearColor(0.5, 0.5, 0.5, 0.9);
gl.clearDepth(1.0);
gl.viewport(0.0, 0.0, canvas.width, canvas.height);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); // 将旋转矩阵传输给顶点着色器
gl.uniformMatrix4fv(Pmatrix, false, proj_matrix);
gl.uniformMatrix4fv(Vmatrix, false, view_matrix);
gl.uniformMatrix4fv(Mmatrix, false, mov_matrix); gl.drawElements(gl.TRIANGLES, indices.length, gl.UNSIGNED_SHORT, 0);
window.requestAnimationFrame(animate);
} animate(0); /*========================= MATRIX ========================= */ function get_projection(angle, a, zMin, zMax) {
var ang = Math.tan((angle*.5)*Math.PI/180);//angle*.5
return [
0.5/ang, 0 , 0, 0,
0, 0.5*a/ang, 0, 0,
0, 0, -(zMax+zMin)/(zMax-zMin), -1,
0, 0, (-2*zMax*zMin)/(zMax-zMin), 0
];
} //z轴旋转
function rotateZ(m, angle) {
var c = Math.cos(angle);
var s = Math.sin(angle);
var mv0 = m[0], mv4 = m[4], mv8 = m[8]; m[0] = c*m[0]-s*m[1];
m[4] = c*m[4]-s*m[5];
m[8] = c*m[8]-s*m[9];
m[1] = c*m[1]+s*mv0;
m[5] = c*m[5]+s*mv4;
m[9] = c*m[9]+s*mv8;
} } </script>
</html>