Unity Shader Example 27 (Noise)

Shader "TestNoise"{Properties{_DissolveDirectTex ("Dissolve Direct Texture", 2D) = "white" {}_NoiseWidth("Noise Width",  Range(0, 2)) = 1_NoisePow("Noise Pow", Range(0, 2)) = 1_Percent("Dissolve Percent", Range(0, 2)) = 0.1}SubShader{Tags { "RenderType"="Opaque" }Pass{CGPROGRAM#pragma vertex vert#pragma fragment frag// make fog work//#pragma multi_compile_fog#include "UnityCG.cginc"struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;float2 uv2 : TEXCOORD1;};struct v2f{float2 uv : TEXCOORD0;float2 uv2 : TEXCOORD1;//UNITY_FOG_COORDS(1)float4 vertex : SV_POSITION;};sampler2D _DissolveDirectTex;float4 _DissolveDirectTex_ST;float _NoiseWidth;float _NoisePow;float _Percent;float2 hash22(float2 p){p = float2(dot(p, float2(127.1, 311.7)),dot(p, float2(269.5, 183.3)));return -1.0 + 2.0 * frac( sin(p) * 43758.5453123);}float noise(float2 p){float2 i = floor(p.xy);float2 f = frac(p.xy);// Ease Curve  //vec2 u = f*f*(3.0-2.0*f);  float2 u = f*f*f*(6.0*f*f - 15.0*f + 10.0);return lerp(lerp(dot(hash22(i + float2(0.0, 0.0)), f - float2(0.0, 0.0)),dot(hash22(i + float2(1.0, 0.0)), f - float2(1.0, 0.0)), u.x),lerp(dot(hash22(i + float2(0.0, 1.0)), f - float2(0.0, 1.0)),dot(hash22(i + float2(1.0, 1.0)), f - float2(1.0, 1.0)), u.x), u.y);}float noise_fractal(float2 p){p *= 5.0;float2x2 m = float2x2(1.6, 1.2, -1.2, 1.6);float f = 0.5000 * noise(p); p = mul(m,p);f += 0.2500*noise(p); p = mul(m, p);f += 0.1250*noise(p); p = mul(m, p);f += 0.0625*noise(p); p = mul(m, p);return f;}float noise_sum_abs(float2 p){float f = 0.0;p = p * 7.0;f += 1.0000 * abs(noise(p)); p = 2.0 * p;f += 0.5000 * abs(noise(p)); p = 2.0 * p;f += 0.2500 * abs(noise(p)); p = 2.0 * p;f += 0.1250 * abs(noise(p)); p = 2.0 * p;f += 0.0625 * abs(noise(p)); p = 2.0 * p;return f;}float hash21(float2 p){return frac(sin(dot(p, float2(12.9898, 78.233))) * 43758.5453);//vec3 p3  = fract(vec3(p.xyx) * .1931);  //p3 += dot(p3, p3.yzx + 19.19);  //return fract((p3.x + p3.y) * p3.z);  }float value_noise(float2 p){p *= 56.0;float2 pi = floor(p);//vec2 pf = p - pi;  float2 pf = frac(p);float2 w = pf * pf * (3.0 - 2.0 * pf);// 它把原来的梯度替换成了一个简单的伪随机值，我们也不需要进行点乘操作，  // 而直接把晶格顶点处的随机值按权重相加即可。  return lerp(lerp(hash21(pi + float2(0.0, 0.0)), hash21(pi + float2(1.0, 0.0)), w.x),lerp(hash21(pi + float2(0.0, 1.0)), hash21(pi + float2(1.0, 1.0)), w.x),w.y);}float simplex_noise(float2 p){const float K1 = 0.366025404; // (sqrt(3)-1)/2;  const float K2 = 0.211324865; // (3-sqrt(3))/6;    // 变换到新网格的(0, 0)点  float2 i = floor(p + (p.x + p.y) * K1);// i - (i.x+i.y)*K2换算到旧网格点  // a:变形前输入点p到该网格点的距离  float2 a = p - (i - (i.x + i.y) * K2);float2 o = (a.x < a.y) ? float2(0.0, 1.0) : float2(1.0, 0.0);// 新网格(1.0, 0.0)或(0.0, 1.0)  // b = p - (i+o - (i.x + i.y + 1.0)*K2);  float2 b = a - o + K2;// 新网格(1.0, 1.0)  // c = p - (i+vec2(1.0, 1.0) - (i.x+1.0 + i.y+1.0)*K2);  float2 c = a - 1.0 + 2.0 * K2;// 计算每个顶点的权重向量，r^2 = 0.5  float2 h = max(0.5 - float3(dot(a, a), dot(b, b), dot(c, c)), 0.0);// 每个顶点的梯度向量和距离向量的点乘，然后再乘上权重向量  float2 n = h * h * h * h * float3(dot(a, hash22(i)), dot(b, hash22(i + o)), dot(c, hash22(i + 1.0)));// 之所以乘上70，是在计算了n每个分量的和的最大值以后得出的，这样才能保证将n各个分量相加以后的结果在[-1, 1]之间  return dot(float3(70.0, 70.0, 70.0), n);}v2f vert (appdata v){v2f o;o.vertex = UnityObjectToClipPos(v.vertex);o.uv = TRANSFORM_TEX(v.uv, _DissolveDirectTex);o.uv2 = v.uv2;return o;}fixed4 frag (v2f i) : SV_Target{fixed4 col = tex2D(_DissolveDirectTex, i.uv2);float factor = _Percent - col.r - value_noise(_NoisePow * i.uv2) * _NoiseWidth;float factorRes = ceil(factor);col = lerp(fixed4(1, 1, 1, 1), fixed4(0, 0, 0, 1), factorRes);return col;/*//return fixed4(noise(_pow * i.uv2), 0, 0, 1);//return fixed4(noise_fractal(_pow * i.uv2), 0, 0, 1);return fixed4(noise_sum_abs(_pow * i.uv2), 0, 0, 1);//return fixed4(value_noise(_pow * i.uv2), 0, 0, 1);//return fixed4(simplex_noise(_pow * i.uv2), 0, 0, 1);*/}ENDCG}}}

参考：

Shader特效——实现“噪声”【基于ShaderToy】【GLSL】

http://blog.csdn.net/panda1234lee/article/details/52085375