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ThreeJS-3D教学十四：ShaderMaterial（length、fract、step）
上面这篇主要是操作 fragmentShader 片元着色器，实现对物体颜色的修改，这次咱们来看下修改 vertexShader 顶点着色器，这个其实就是位移各个顶点的位置。
接下来我们先介绍下 noise 噪声函数（Perlin Noise、Simplex Noise 等）能使相邻的点（一维、二维、三维的点都行）产生相近的数值，而不是 random 随机函数那种每个位置的数值都和附近无关的效果。
noise 函数不是内置函数但有现成的实现可以使用，搜索 glsl noise function，就能找到很多实现。这里我们先演示在三维顶点坐标上使用 noise 的效果，因此先复制粘帖接收 vec3 格式参数的 cnoise() 到 main 函数之前然后进行使用。
vec4 permute(vec4 x){return mod(((x*34.0)+1.0)*x, 289.0);}
vec4 taylorInvSqrt(vec4 r){return 1.79284291400159 - 0.85373472095314 * r;}
vec3 fade(vec3 t) {return t*t*t*(t*(t*6.0-15.0)+10.0);}float cnoise(vec3 P){vec3 Pi0 = floor(P); // Integer part for indexingvec3 Pi1 = Pi0 + vec3(1.0); // Integer part + 1Pi0 = mod(Pi0, 289.0);Pi1 = mod(Pi1, 289.0);vec3 Pf0 = fract(P); // Fractional part for interpolationvec3 Pf1 = Pf0 - vec3(1.0); // Fractional part - 1.0vec4 ix = vec4(Pi0.x, Pi1.x, Pi0.x, Pi1.x);vec4 iy = vec4(Pi0.yy, Pi1.yy);vec4 iz0 = Pi0.zzzz;vec4 iz1 = Pi1.zzzz;vec4 ixy = permute(permute(ix) + iy);vec4 ixy0 = permute(ixy + iz0);vec4 ixy1 = permute(ixy + iz1);vec4 gx0 = ixy0 / 7.0;vec4 gy0 = fract(floor(gx0) / 7.0) - 0.5;gx0 = fract(gx0);vec4 gz0 = vec4(0.5) - abs(gx0) - abs(gy0);vec4 sz0 = step(gz0, vec4(0.0));gx0 -= sz0 * (step(0.0, gx0) - 0.5);gy0 -= sz0 * (step(0.0, gy0) - 0.5);vec4 gx1 = ixy1 / 7.0;vec4 gy1 = fract(floor(gx1) / 7.0) - 0.5;gx1 = fract(gx1);vec4 gz1 = vec4(0.5) - abs(gx1) - abs(gy1);vec4 sz1 = step(gz1, vec4(0.0));gx1 -= sz1 * (step(0.0, gx1) - 0.5);gy1 -= sz1 * (step(0.0, gy1) - 0.5);vec3 g000 = vec3(gx0.x,gy0.x,gz0.x);vec3 g100 = vec3(gx0.y,gy0.y,gz0.y);vec3 g010 = vec3(gx0.z,gy0.z,gz0.z);vec3 g110 = vec3(gx0.w,gy0.w,gz0.w);vec3 g001 = vec3(gx1.x,gy1.x,gz1.x);vec3 g101 = vec3(gx1.y,gy1.y,gz1.y);vec3 g011 = vec3(gx1.z,gy1.z,gz1.z);vec3 g111 = vec3(gx1.w,gy1.w,gz1.w);vec4 norm0 = taylorInvSqrt(vec4(dot(g000, g000), dot(g010, g010), dot(g100, g100), dot(g110, g110)));g000 *= norm0.x;g010 *= norm0.y;g100 *= norm0.z;g110 *= norm0.w;vec4 norm1 = taylorInvSqrt(vec4(dot(g001, g001), dot(g011, g011), dot(g101, g101), dot(g111, g111)));g001 *= norm1.x;g011 *= norm1.y;g101 *= norm1.z;g111 *= norm1.w;float n000 = dot(g000, Pf0);float n100 = dot(g100, vec3(Pf1.x, Pf0.yz));float n010 = dot(g010, vec3(Pf0.x, Pf1.y, Pf0.z));float n110 = dot(g110, vec3(Pf1.xy, Pf0.z));float n001 = dot(g001, vec3(Pf0.xy, Pf1.z));float n101 = dot(g101, vec3(Pf1.x, Pf0.y, Pf1.z));float n011 = dot(g011, vec3(Pf0.x, Pf1.yz));float n111 = dot(g111, Pf1);vec3 fade_xyz = fade(Pf0);vec4 n_z = mix(vec4(n000, n100, n010, n110), vec4(n001, n101, n011, n111), fade_xyz.z);vec2 n_yz = mix(n_z.xy, n_z.zw, fade_xyz.y);float n_xyz = mix(n_yz.x, n_yz.y, fade_xyz.x); return 2.2 * n_xyz;
}
下面我们先看下案例效果：
11111
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title><style>body {width: 100%;height: 100%;}* {margin: 0;padding: 0;}.label {font-size: 20px;color: #000;font-weight: 700;}.circle {width: 20px;height: 20px;border-radius: 10px;position: absolute;left: 0;top: 0;background-color: red;z-index: 1000;}#container {position: relative;width: 100%;height: 100vh;}</style>
</head>
<body>
<div class="circle"></div>
<div id="container"></div>
<script id="vshaderBox" type="x-shader/x-vertex">uniform float uTime;void main() {// sin 0-1之间的数 cos 1-0之间的数vec3 newPos = position * cos(uTime);gl_Position = projectionMatrix * modelViewMatrix * vec4(newPos, 1.0);}
</script>
<scri