三角形平移
image.png
1、公式实现
<!DOCTYPE HTML>
<head>
</head>
<html>
<body onload="main()">
<canvas id="webgl" width="500" height="500" style="border: 1px solid #ff0000;">
</canvas>
<script type="text/javascript">
//顶点着色器程序
var VSHADER_SOURCE =
'attribute vec4 a_Position;\n'+
'uniform vec4 u_Translation;\n'+
'void main(){\n'+
'gl_Position = a_Position + u_Translation;\n'+
'}\n';
//片元着色器程序
var FSHADER_SOURCE =
'void main(){'+
'gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);\n'+
'}\n';
function main(){
//获取<canvas>元素
var canvas = document.getElementById("webgl");
if(!canvas){
console.log('error');
return;
}
//获取绘制三维图形的绘图上下文
var gl = canvas.getContext('webgl');
// 创建着色器对象
const fShader = gl.createShader(gl.FRAGMENT_SHADER);
const vShader = gl.createShader(gl.VERTEX_SHADER);
// 将着色器源码写入对象
gl.shaderSource(vShader, VSHADER_SOURCE);
gl.shaderSource(fShader, FSHADER_SOURCE);
// 编译着色器
// 创建程序
const program = gl.createProgram();
// 程序绑定着色器
gl.attachShader(program, vShader);
gl.attachShader(program, fShader);
// 链接程序
gl.linkProgram(program);
// 使用程序
gl.useProgram(program);
//在x,y,z方向上平移的距离
var Tx = 0.5, Ty = 0.5, Tz = 0.5;
var u_Translation = gl.getUniformLocation(program, 'u_Translation');
gl.uniform4f(u_Translation, Tx, Ty, Tz, 0.0);
var n = initVertexBuffers(gl);
if(n < 0){
console.log('Failed to set positions of vertices');
return;
}
gl.drawArrays(gl.TRIANGLES, 0, n);
function initVertexBuffers(gl){
var vertices = new Float32Array([0.0, 0.5, -0.5, -0.5, 0.5, -0.5]); //坐标点位置
var n = 3; //坐标点个数
//创建缓冲区对象
var vertexBuffer = gl.createBuffer();
if(!vertexBuffer){
console.log('Failed to create the buffer object');
return -1;
}
//将缓冲区对象绑定到目标
gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
//向缓冲区对象中写入数据
gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW);
var a_Position = gl.getAttribLocation(program, 'a_Position');
if(a_Position < 0){
console.log('Failed to get the storage location of a_Position');
return;
}
//将缓冲区对象分配给a_Position变量
gl.vertexAttribPointer(a_Position, 2, gl.FLOAT, false, 0, 0);
//连接a_Position变量与分配给它的缓冲区对象
gl.enableVertexAttribArray(a_Position);
return n;
}
}
</script>
</body>
</html>
2、矩阵实现
<!DOCTYPE HTML>
<head>
</head>
<html>
<body onload="main()">
<canvas id="webgl" width="500" height="500" style="border: 1px solid #ff0000;">
</canvas>
<script type="text/javascript">
//顶点着色器程序
var VSHADER_SOURCE =
'attribute vec4 a_Position;\n'+
'uniform mat4 u_Translation;\n'+
'void main(){\n'+
'gl_Position = u_Translation * a_Position;\n'+
'}\n';
//片元着色器程序
var FSHADER_SOURCE =
'void main(){'+
'gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);\n'+
'}\n';
function main(){
//获取<canvas>元素
var canvas = document.getElementById("webgl");
if(!canvas){
console.log('error');
return;
}
//获取绘制三维图形的绘图上下文
var gl = canvas.getContext('webgl');
// 创建着色器对象
const fShader = gl.createShader(gl.FRAGMENT_SHADER);
const vShader = gl.createShader(gl.VERTEX_SHADER);
// 将着色器源码写入对象
gl.shaderSource(vShader, VSHADER_SOURCE);
gl.shaderSource(fShader, FSHADER_SOURCE);
// 编译着色器
// 创建程序
const program = gl.createProgram();
// 程序绑定着色器
gl.attachShader(program, vShader);
gl.attachShader(program, fShader);
// 链接程序
gl.linkProgram(program);
// 使用程序
gl.useProgram(program);
//在x,y,z方向上平移的距离
var Tx = 0.5, Ty = 0.5, Tz = 0.5;
var translation = 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,
Tx, Ty, Tz, 1.0
]);
var u_Translation = gl.getUniformLocation(program, 'u_Translation');
gl.uniformMatrix4fv(u_Translation, false, translation);
var n = initVertexBuffers(gl);
if(n < 0){
console.log('Failed to set positions of vertices');
return;
}
gl.drawArrays(gl.TRIANGLES, 0, n);
function initVertexBuffers(gl){
var vertices = new Float32Array([0.0, 0.5, -0.5, -0.5, 0.5, -0.5]); //坐标点位置
var n = 3; //坐标点个数
//创建缓冲区对象
var vertexBuffer = gl.createBuffer();
if(!vertexBuffer){
console.log('Failed to create the buffer object');
return -1;
}
//将缓冲区对象绑定到目标
gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
//向缓冲区对象中写入数据
gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW);
var a_Position = gl.getAttribLocation(program, 'a_Position');
if(a_Position < 0){
console.log('Failed to get the storage location of a_Position');
return;
}
//将缓冲区对象分配给a_Position变量
gl.vertexAttribPointer(a_Position, 2, gl.FLOAT, false, 0, 0);
//连接a_Position变量与分配给它的缓冲区对象
gl.enableVertexAttribArray(a_Position);
return n;
}
}
</script>
</body>
</html>
image.png
三角形旋转
image.png
image.png
image.png
1、公式代码实现：
<!DOCTYPE HTML>
<head>
</head>
<html>
<body onload="main()">
<canvas id="webgl" width="500" height="500" style="border: 1px solid #ff0000;">
</canvas>
<script type="text/javascript">
//顶点着色器程序
var VSHADER_SOURCE =
'attribute vec4 a_Position;\n'+
'uniform float u_CosB, u_SinB;\n'+
'void main(){\n'+
'gl_Position.x = a_Position.x * u_CosB - a_Position.y * u_SinB;\n'+
'gl_Position.y = a_Position.x * u_SinB + a_Position.y * u_CosB;\n'+
'gl_Position.z = a_Position.z;\n'+
'gl_Position.w = 1.0;\n'+
'}\n';
//片元着色器程序
var FSHADER_SOURCE =
'void main(){'+
'gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);\n'+
'}\n';
function main(){
//获取<canvas>元素
var canvas = document.getElementById("webgl");
if(!canvas){
console.log('error');
return;
}
//获取绘制三维图形的绘图上下文
var gl = canvas.getContext('webgl');
// 创建着色器对象
const fShader = gl.createShader(gl.FRAGMENT_SHADER);
const vShader = gl.createShader(gl.VERTEX_SHADER);
// 将着色器源码写入对象
gl.shaderSource(vShader, VSHADER_SOURCE);
gl.shaderSource(fShader, FSHADER_SOURCE);
// 编译着色器
// 创建程序
const program = gl.createProgram();
// 程序绑定着色器
gl.attachShader(program, vShader);
gl.attachShader(program, fShader);
// 链接程序
gl.linkProgram(program);
// 使用程序
gl.useProgram(program);
//绕z轴旋转
var ANGLE = 45.0;
var radian = Math.PI * ANGLE / 180.0;
var cosB = Math.cos(radian);
var sinB = Math.sin(radian);
var u_CosB = gl.getUniformLocation(program, 'u_CosB');
var u_SinB = gl.getUniformLocation(program, 'u_SinB');
gl.uniform1f(u_CosB, cosB);
gl.uniform1f(u_SinB, sinB);
var n = initVertexBuffers(gl);
if(n < 0){
console.log('Failed to set positions of vertices');
return;
}
gl.drawArrays(gl.TRIANGLES, 0, n);
function initVertexBuffers(gl){
var vertices = new Float32Array([0.0, 0.5, -0.5, -0.5, 0.5, -0.5]); //坐标点位置
var n = 3; //坐标点个数
//创建缓冲区对象
var vertexBuffer = gl.createBuffer();
if(!vertexBuffer){
console.log('Failed to create the buffer object');
return -1;
}
//将缓冲区对象绑定到目标
gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
//向缓冲区对象中写入数据
gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW);
var a_Position = gl.getAttribLocation(program, 'a_Position');
if(a_Position < 0){
console.log('Failed to get the storage location of a_Position');
return;
}
//将缓冲区对象分配给a_Position变量
gl.vertexAttribPointer(a_Position, 2, gl.FLOAT, false, 0, 0);
//连接a_Position变量与分配给它的缓冲区对象
gl.enableVertexAttribArray(a_Position);
return n;
}
}
</script>
</body>
</html>
image.png
image.png
2、变换矩阵代码实现：
<!DOCTYPE HTML>
<head>
</head>
<html>
<body onload="main()">
<canvas id="webgl" width="500" height="500" style="border: 1px solid #ff0000;">
</canvas>
<script type="text/javascript">
//顶点着色器程序
var VSHADER_SOURCE =
'attribute vec4 a_Position;\n'+
'uniform mat4 u_xformMatrix;\n'+
'void main(){\n'+
'gl_Position = u_xformMatrix * a_Position;\n'+
'}\n';
//片元着色器程序
var FSHADER_SOURCE =
'void main(){'+
'gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);\n'+
'}\n';
function main(){
//获取<canvas>元素
var canvas = document.getElementById("webgl");
if(!canvas){
console.log('error');
return;
}
//获取绘制三维图形的绘图上下文
var gl = canvas.getContext('webgl');
// 创建着色器对象
const fShader = gl.createShader(gl.FRAGMENT_SHADER);
const vShader = gl.createShader(gl.VERTEX_SHADER);
// 将着色器源码写入对象
gl.shaderSource(vShader, VSHADER_SOURCE);
gl.shaderSource(fShader, FSHADER_SOURCE);
// 编译着色器
// 创建程序
const program = gl.createProgram();
// 程序绑定着色器
gl.attachShader(program, vShader);
gl.attachShader(program, fShader);
// 链接程序
gl.linkProgram(program);
// 使用程序
gl.useProgram(program);
//绕z轴旋转
var ANGLE = 45.0;
var radian = Math.PI * ANGLE / 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 u_xformMatrix = gl.getUniformLocation(program, 'u_xformMatrix');
gl.uniformMatrix4fv(u_xformMatrix, false, xformMatrix);;
var n = initVertexBuffers(gl);
if(n < 0){
console.log('Failed to set positions of vertices');
return;
}
gl.drawArrays(gl.TRIANGLES, 0, n);
function initVertexBuffers(gl){
var vertices = new Float32Array([0.0, 0.5, -0.5, -0.5, 0.5, -0.5]); //坐标点位置
var n = 3; //坐标点个数
//创建缓冲区对象
var vertexBuffer = gl.createBuffer();
if(!vertexBuffer){
console.log('Failed to create the buffer object');
return -1;
}
//将缓冲区对象绑定到目标
gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
//向缓冲区对象中写入数据
gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW);
var a_Position = gl.getAttribLocation(program, 'a_Position');
if(a_Position < 0){
console.log('Failed to get the storage location of a_Position');
return;
}
//将缓冲区对象分配给a_Position变量
gl.vertexAttribPointer(a_Position, 2, gl.FLOAT, false, 0, 0);
//连接a_Position变量与分配给它的缓冲区对象
gl.enableVertexAttribArray(a_Position);
return n;
}
}
</script>
</body>
</html>
image.png
三角形缩放
image.png
1、公式实现
<!DOCTYPE HTML>
<head>
</head>
<html>
<body onload="main()">
<canvas id="webgl" width="500" height="500" style="border: 1px solid #ff0000;">
</canvas>
<script type="text/javascript">
//顶点着色器程序
var VSHADER_SOURCE =
'attribute vec4 a_Position;\n'+
'uniform float u_Sx, u_Sy, u_Sz;\n'+
'void main(){\n'+
'gl_Position.x = u_Sx * a_Position.x;\n'+
'gl_Position.y = u_Sy * a_Position.y;\n'+
'gl_Position.z = u_Sz * a_Position.z;\n'+
'gl_Position.w = 1.0;\n'+
'}\n';
//片元着色器程序
var FSHADER_SOURCE =
'void main(){'+
'gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);\n'+
'}\n';
function main(){
//获取<canvas>元素
var canvas = document.getElementById("webgl");
if(!canvas){
console.log('error');
return;
}
//获取绘制三维图形的绘图上下文
var gl = canvas.getContext('webgl');
// 创建着色器对象
const fShader = gl.createShader(gl.FRAGMENT_SHADER);
const vShader = gl.createShader(gl.VERTEX_SHADER);
// 将着色器源码写入对象
gl.shaderSource(vShader, VSHADER_SOURCE);
gl.shaderSource(fShader, FSHADER_SOURCE);
// 编译着色器
// 创建程序
const program = gl.createProgram();
// 程序绑定着色器
gl.attachShader(program, vShader);
gl.attachShader(program, fShader);
// 链接程序
gl.linkProgram(program);
// 使用程序
gl.useProgram(program);
//在x,y,z方向上缩放的比例
var Sx=1.0, Sy=1.5, Sz=1.0;
var u_Sx = gl.getUniformLocation(program, 'u_Sx');
var u_Sy = gl.getUniformLocation(program, 'u_Sy');
var u_Sz = gl.getUniformLocation(program, 'u_Sz');
gl.uniform1f(u_Sx,Sx);
gl.uniform1f(u_Sy,Sy);
gl.uniform1f(u_Sz,Sz);
var n = initVertexBuffers(gl);
if(n < 0){
console.log('Failed to set positions of vertices');
return;
}
gl.drawArrays(gl.TRIANGLES, 0, n);
function initVertexBuffers(gl){
var vertices = new Float32Array([0.0, 0.5, -0.5, -0.5, 0.5, -0.5]); //坐标点位置
var n = 3; //坐标点个数
//创建缓冲区对象
var vertexBuffer = gl.createBuffer();
if(!vertexBuffer){
console.log('Failed to create the buffer object');
return -1;
}
//将缓冲区对象绑定到目标
gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
//向缓冲区对象中写入数据
gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW);
var a_Position = gl.getAttribLocation(program, 'a_Position');
if(a_Position < 0){
console.log('Failed to get the storage location of a_Position');
return;
}
//将缓冲区对象分配给a_Position变量
gl.vertexAttribPointer(a_Position, 2, gl.FLOAT, false, 0, 0);
//连接a_Position变量与分配给它的缓冲区对象
gl.enableVertexAttribArray(a_Position);
return n;
}
}
</script>
</body>
</html>
2、矩阵实现
<!DOCTYPE HTML>
<head>
</head>
<html>
<body onload="main()">
<canvas id="webgl" width="500" height="500" style="border: 1px solid #ff0000;">
</canvas>
<script type="text/javascript">
//顶点着色器程序
var VSHADER_SOURCE =
'attribute vec4 a_Position;\n'+
'uniform mat4 u_Translation;\n'+
'void main(){\n'+
'gl_Position = u_Translation * a_Position;\n'+
'}\n';
//片元着色器程序
var FSHADER_SOURCE =
'void main(){'+
'gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);\n'+
'}\n';
function main(){
//获取<canvas>元素
var canvas = document.getElementById("webgl");
if(!canvas){
console.log('error');
return;
}
//获取绘制三维图形的绘图上下文
var gl = canvas.getContext('webgl');
// 创建着色器对象
const fShader = gl.createShader(gl.FRAGMENT_SHADER);
const vShader = gl.createShader(gl.VERTEX_SHADER);
// 将着色器源码写入对象
gl.shaderSource(vShader, VSHADER_SOURCE);
gl.shaderSource(fShader, FSHADER_SOURCE);
// 编译着色器
// 创建程序
const program = gl.createProgram();
// 程序绑定着色器
gl.attachShader(program, vShader);
gl.attachShader(program, fShader);
// 链接程序
gl.linkProgram(program);
// 使用程序
gl.useProgram(program);
//在x,y,z方向上缩放的比例
var Sx=1.0, Sy=1.5, Sz=1.0;
var translation = new Float32Array([
Sx, 0.0, 0.0, 0.0,
0.0, Sy, 0.0, 0.0,
0.0, 0.0, Sz, 0.0,
0.0, 0.0, 0.0, 1.0
]);
var u_Translation = gl.getUniformLocation(program, 'u_Translation');
gl.uniformMatrix4fv(u_Translation, false, translation);
var n = initVertexBuffers(gl);
if(n < 0){
console.log('Failed to set positions of vertices');
return;
}
gl.drawArrays(gl.TRIANGLES, 0, n);
function initVertexBuffers(gl){
var vertices = new Float32Array([0.0, 0.5, -0.5, -0.5, 0.5, -0.5]); //坐标点位置
var n = 3; //坐标点个数
//创建缓冲区对象
var vertexBuffer = gl.createBuffer();
if(!vertexBuffer){
console.log('Failed to create the buffer object');
return -1;
}
//将缓冲区对象绑定到目标
gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
//向缓冲区对象中写入数据
gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW);
var a_Position = gl.getAttribLocation(program, 'a_Position');
if(a_Position < 0){
console.log('Failed to get the storage location of a_Position');
return;
}
//将缓冲区对象分配给a_Position变量
gl.vertexAttribPointer(a_Position, 2, gl.FLOAT, false, 0, 0);
//连接a_Position变量与分配给它的缓冲区对象
gl.enableVertexAttribArray(a_Position);
return n;
}
}
</script>
</body>
</html>
image.png
示例：旋转的三角形动画
<!DOCTYPE HTML>
<head>
</head>
<html>
<body onload="main()">
<canvas id="webgl" width="500" height="500" style="border: 1px solid #ff0000;">
</canvas>
<script type="text/javascript">
//顶点着色器程序
var VSHADER_SOURCE =
'attribute vec4 a_Position;\n'+
'uniform mat4 u_xformMatrix;\n'+
'void main(){\n'+
'gl_Position = u_xformMatrix * a_Position;\n'+
'}\n';
//片元着色器程序
var FSHADER_SOURCE =
'void main(){'+
'gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);\n'+
'}\n';
function main(){
//获取<canvas>元素
var canvas = document.getElementById("webgl");
if(!canvas){
console.log('error');
return;
}
//获取绘制三维图形的绘图上下文
var gl = canvas.getContext('webgl');
// 创建着色器对象
const fShader = gl.createShader(gl.FRAGMENT_SHADER);
const vShader = gl.createShader(gl.VERTEX_SHADER);
// 将着色器源码写入对象
gl.shaderSource(vShader, VSHADER_SOURCE);
gl.shaderSource(fShader, FSHADER_SOURCE);
// 编译着色器
// 创建程序
const program = gl.createProgram();
// 程序绑定着色器
gl.attachShader(program, vShader);
gl.attachShader(program, fShader);
// 链接程序
gl.linkProgram(program);
// 使用程序
gl.useProgram(program);
//绕z轴旋转
var init_angle = 0.0;
var angle_step = 0.1;
var current_angle = init_angle;
setInterval(function(){
gl.clear(gl.COLOR_BUFFER_BIT);
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 u_xformMatrix = gl.getUniformLocation(program, 'u_xformMatrix');
gl.uniformMatrix4fv(u_xformMatrix, false, xformMatrix);;
var n = initVertexBuffers(gl);
if(n < 0){
console.log('Failed to set positions of vertices');
return;
}
gl.drawArrays(gl.TRIANGLES, 0, n);
current_angle = current_angle + angle_step;
}, 10);
function initVertexBuffers(gl){
var vertices = new Float32Array([0.0, 0.3, -0.1, -0.1, 0.7, -0.7]); //坐标点位置
var n = 3; //坐标点个数
//创建缓冲区对象
var vertexBuffer = gl.createBuffer();
if(!vertexBuffer){
console.log('Failed to create the buffer object');
return -1;
}
//将缓冲区对象绑定到目标
gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
//向缓冲区对象中写入数据
gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW);
var a_Position = gl.getAttribLocation(program, 'a_Position');
if(a_Position < 0){
console.log('Failed to get the storage location of a_Position');
return;
}
//将缓冲区对象分配给a_Position变量
gl.vertexAttribPointer(a_Position, 2, gl.FLOAT, false, 0, 0);
//连接a_Position变量与分配给它的缓冲区对象
gl.enableVertexAttribArray(a_Position);
return n;
}
}
</script>
</body>
</html>
不同时刻的动画截图
image.png
image.png