还是比较节省性能的,这个还是包含了生成测试数据的性能,实际应用如果是直接通信获得数据应该还能少几毫秒吧!
用了React,但是关系不大
WebGL的基础用法(推荐看一看掘金里的一个教程:WebGL 入门与实践)
有兴趣应该读一读这个的源码GPU.JS,因为一开始偷学了一手flatten2dArrayTo这个方法,后来发现实现上述效果的功能的实现原理和GPU
.JS的加速原理差不多的
需要稍微写一个fragmentShader的代码;因为要把大多数耗时的计算扔到这个里面执行
需要将测试数据生成的matrix二维数组通过flatten2dArrayTo转化为Uint8Array
const size = { width: 1400, height: 600 };
const sourceArr = new Float32Array(size.width * size.height).fill(-999.0);
const matrix = []; // 一个二维数组
setInterval(() => {
const res = [];
// TODO 按某些规则生成一行数据放入res
matrix.unshift(res);
if (matrix.length > size.height) {
matrix.pop();
}
flatten2dArrayTo(matrix, sourceArr);
}, 20);
// 二维数组转一维数组
const flatten2dArrayTo = (array, target) => {
let offset = 0;
for (let y = 0; y < array.length; y += 1) {
target.set(array[y], offset);
offset += array[y].length;
}
};
// ...实际给GL使用再将Float32Array转为Uint8Array
const d = sourceArr;
new Uint8Array(d.buffer);
// ...
需要给GL定义:调色板作为第0个纹理,数据转化为的Uint8Array当作第1个纹理
const drawDance = (palette, data, width, height, l) => {
if (canRef.current) {
const gl = canRef.current.getContext?.('webgl');
if (gl) {
// 这个暂时没用
const lengthHandle = gl.getUniformLocation(gl.program, 'length');
gl.uniform1f(lengthHandle, l);
// 纹理0:一个256*2的调色板
const paletteLoc = gl.getUniformLocation(gl.program, 'u_Palette');
gl.uniform1i(paletteLoc, 0);
// 纹理1:Float32Array转为Uint8Array的数据纹理
const samplerLoc = gl.getUniformLocation(gl.program, 'u_Sampler');
gl.uniform1i(samplerLoc, 1);
// 纹理0放入
gl.activeTexture(gl.TEXTURE0);
const texture1 = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, texture1);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGB, 256 * 2, 1, 0, gl.RGB, gl.UNSIGNED_BYTE, palette);
// 纹理1放入
gl.activeTexture(gl.TEXTURE1);
const texture2 = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, texture2);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, width, height, 0, gl.RGBA, gl.UNSIGNED_BYTE, bvbv(data));
// canvas那么大的一个网格
drawBuffer(gl, [-1.0, 1.0, -1.0, -1.0, 1.0, 1.0, 1.0, -1.0], 'a_Position');
// 释放纹理
gl.deleteTexture(texture1);
gl.deleteTexture(texture2);
}
}
};
canvas尺寸变化的时候告诉GL {width,height} 方便在片元着色器中取到对应点的value
const onResize = useCallback(() => {
const { offsetHeight: height, offsetWidth: width } = containerRef.current || {};
const can = React.createElement('canvas', {
width,
height,
style: { background: '#90202020' },
ref: canRef,
});
containerRef.current && render(can, containerRef.current);
const gl = canRef.current.getContext('webgl');
if (gl) {
// 重新设置gl视口,gl的Oxy在canvas的中心
initShaders(gl, VSHADER_SOURCE, FSHADER_SOURCE);
gl.viewport(0, 0, width, height);
const widthHandle = gl.getUniformLocation(gl.program, 'width');
const heightHandle = gl.getUniformLocation(gl.program, 'height');
gl.uniform1f(widthHandle, width);
gl.uniform1f(heightHandle, height);
// 缩放相关的不重要
const x1H = gl.getUniformLocation(gl.program, 'x1');
const x2H = gl.getUniformLocation(gl.program, 'x2');
gl.uniform1f(x1H, 0);
gl.uniform1f(x2H, width);
}
}, []);
一个fragmentShader,主要是要把通过像素位置获取对应二维的数组中对应的数据值(重点是那个decode32函数,网上找了挺久的How do I convert a vec4 rgba value to a float? ),然后根据最小最大和调色板确定绘制的颜色
precision mediump float;
uniform float width;
uniform float height;
uniform float length;
uniform float x1;
uniform float x2;
uniform sampler2D u_Palette;
uniform sampler2D u_Sampler;
vec2 reslution =vec2(width,height);
highp float decode32(highp vec4 rgba) {
highp float Sign = 1.0 - step(128.0,rgba[0])*2.0;
highp float Exponent = 2.0 * mod(rgba[0],128.0) + step(128.0,rgba[1]) - 127.0;
highp float Mantissa = mod(rgba[1],128.0)65536.0 + rgba[2]256.0 +rgba[3] + float(0x800000);
highp float Result = Sign * exp2(Exponent) * (Mantissa * exp2(-23.0 ));
return Result;
}
void main(){
// gl_FragColor=vec4(gl_FragCoord.xyx/reslution.xyx,1.0);
if(gl_FragCoord.y < 10.0){
// 简单画个调色板示意图
gl_FragColor=texture2D(u_Palette,gl_FragCoord.xy/reslution.xy);
}
else{
// 绘制数据点
float xx=x1+gl_FragCoord.x/reslution.x*(x2-x1);
vec2 pos = vec2(xx,reslution.y-gl_FragCoord.y)/vec2(reslution.x,reslution.y);
vec4 color=texture2D(u_Sampler,pos)*255.0;
float val=decode32(color.abgr);
if(val < -99.0){
gl_FragColor=vec4(0.0,0.0,0.0,1.0);
}
else{
gl_FragColor=texture2D(u_Palette,vec2((val+20.0)/100.0,1.0));
}
}
}
基本上述代码过程就能实现了;直接看源码吧:ctrlcv->AudioDance8 ctrlCV工程师
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