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webgl-pointer.html
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webgl-pointer.html
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>合并属性和图形绘制</title>
<script src="./js/initShader.js"></script>
<style>
html,
body {
width: 100vw;
height: 100vh;
padding: 0;
margin: 0;
display: flex;
justify-content: center;
align-items: center;
}
body::after {
content: '';
display: block;
width: 1px;
height: 500px;
background-color: aqua;
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
}
body::before {
content: '';
display: block;
width: 500px;
height: 1px;
background-color: darkviolet;
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
}
</style>
</head>
<body>
<canvas id="draw1" width="400" height="400" style="background: pink;">浏览器不支持canvas</canvas>
</body>
</html>
<script type="module">
const draw1 = document.getElementById('draw1');
const gl = draw1.getContext('webgl');
//attribute只传递顶点数量
const VERTEX_SHADER_SOURCE = `
attribute vec4 aPosition;
attribute float aPointSize;
void main(){
gl_Position=aPosition;
gl_PointSize=aPointSize;
}
`; //顶点
//默认vec4（0.0，0.0，0.0，1.0）(x,y,z,w),w齐次坐标，最终的三维坐标为（x/w,y/w,z/w），当w无限接近0说明坐标越远
const FRAGMENT_SHADER_SOURCE = `
precision mediump float;
uniform vec4 uColor;
void main(){
gl_FragColor=uColor;
}
`; //片元 (rgba)
const FRAGMENT_SHADER_SOURCE2 = `
precision mediump float;
uniform vec2 uColor;
void main(){
gl_FragColor=vec4(uColor.r,uColor.g,0.0,1.0);
}
`;//uniform统一声明，所有点颜色一样
const program = initShader(gl, VERTEX_SHADER_SOURCE, FRAGMENT_SHADER_SOURCE2);
const aPosition = gl.getAttribLocation(program, 'aPosition');//第二个参数是源码里attribute声明的变量名
const aPointSize = gl.getAttribLocation(program, 'aPointSize');//第二个参数是源码里attribute声明的变量名
const uColor = gl.getUniformLocation(program, 'uColor');
gl.uniform2f(uColor, 1.0, 1.0);
//用类型化数组创建顶点数据，合并顶点location和size
const points = new Float32Array([
-0.5, -0.5, 10.0,
0.5, -0.5, 20.0,
// 0.0, 0.5, 30.0,
-0.5, 0.5, 30.0,
0.5, 0.5, 20.0,
// 0.5, 0.8, 10.0,
// 0.8, 0.5, 10.0
])
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//获取属性字节数
gl.vertexAttribPointer(aPosition, 2, gl.FLOAT, false, BYTES * 3, 0);
void gl.enableVertexAttribArray(aPosition);
gl.vertexAttribPointer(aPointSize, 1, gl.FLOAT, false, BYTES * 3, BYTES * 2);
void gl.enableVertexAttribArray(aPointSize);
// gl.drawArrays(gl.POINTS, 0, 3);//size属性只在点类型下有效
// gl.drawArrays(gl.LINES, 0, 3);
// gl.drawArrays(gl.LINE_STRIP, 0, 3);//绘制连续线段
// gl.drawArrays(gl.LINE_LOOP, 0, 3);//绘制闭合
// gl.drawArrays(gl.TRIANGLES, 0, 3);//绘制三角形
// gl.drawArrays(gl.TRIANGLES, 0, 6);
// gl.drawArrays(gl.TRIANGLE_FAN, 0, 4);
gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
</script>