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webgl-draw.html
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webgl-draw.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>webgl入门</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');
const VERTEX_SHADER_SOURCE = `
attribute vec4 aPosition;
void main(){
gl_Position=aPosition;
gl_PointSize=10.0;
}
`; //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
//attribute只传递顶点数量
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);
}
`;
const FRAGMENT_SHADER_SOURCE3 = `
precision mediump float;
uniform float uColor;
void main(){
gl_FragColor=vec4(uColor,0.0,0.0,1.0);
}
`;//这是vec为1的情况
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 uColor = gl.getUniformLocation(program, 'uColor');
// gl.uniform4f(uColor, 1.0, 1.0, 0.0, 1.0);
const points = [];
draw1.onmousemove = (e) => {
const x = e.clientX;
const y = e.clientY;
const { top, left } = e.target.getBoundingClientRect();
const domX = x - left;//点击点距离画布左侧的距离
const domY = y - top;
//计算坐标使其范围（-1，1）
//X先减画布宽度一半，再除以画布宽度一半
//画布高度一半减Y，再除以画布高度一半
const halfW = draw1.offsetWidth / 2;
const halfH = draw1.offsetHeight / 2;
const clickX = (domX - halfW) / halfW;
const clickY = (halfH - domY) / halfH;
// points.push([clickX, clickY]);
// for (const index in points) {
gl.vertexAttrib2f(aPosition, clickX, clickY);
gl.uniform2f(uColor, clickX, clickY);
gl.drawArrays(gl.POINTS, 0, 1);
// }
}
//循环绘制移动点
// let x = 0;
// setInterval(() => {
// x += 0.1;
// if (x > 1.0) {
// x = 0;
// }
// gl.vertexAttrib4f(aPosition, x, 0.0, 0.0, 1.0);
// gl.drawArrays(gl.POINTS, 0, 1);
// }, 200);
</script>