毛绒绒的效果

https://www.freesion.com/article/20771238845/

核心的算法通过多个pass，从里到外一层一层的糊上一层透明diffuse，越靠外面的地方层次越少看起来越稀疏，越模糊

FurHelper.cginc

struct v2f {
    float4 pos : SV_POSITION;
    half2 uv : TEXCOORD0;
    half2 uv1 : TEXCOORD1;
    fixed4 diff : COLOR;
};
 
float _FurLength;
sampler2D _MainTex;
float4 _MainTex_ST;
sampler2D _FurTex;
float4 _FurTex_ST;
float _Blur;
 
v2f vert(appdata_base v) {
    v2f o;
    v.vertex.xyz += v.normal * _FurLength * FURSTEP;
    o.pos = UnityObjectToClipPos(v.vertex);
    o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
    o.uv1 = TRANSFORM_TEX(v.texcoord, _FurTex);
    float3 worldNormal = normalize(mul(v.normal, (float3x3) unity_WorldToObject));
    o.diff = LambertDiffuse(worldNormal);
    o.diff.a = 1 - (FURSTEP * FURSTEP);
    float4 worldPos = mul(unity_ObjectToWorld ,v.vertex);
    o.diff.a += dot(normalize(_WorldSpaceCameraPos.xyz- v.vertex), worldNormal) - _Blur;
    return o;
}
 
float _CutOff;
float _Thickness;
 
fixed4 frag(v2f i) : SV_Target {
    fixed4 col = tex2D(_MainTex, i.uv);
    fixed alpha = tex2D(_FurTex, i.uv1).r;
    col *= i.diff;
    col.a *= step(lerp(_CutOff, _CutOff + _Thickness, FURSTEP), alpha);
    return col;
}

FurShader.shader

Shader "Custom/FurShader"
{
    Properties
    {
        _MainTex("Texture", 2D) = "white" {}
    _FurTex("Fur pattern", 2D) = "white" {}
    _Diffuse("Diffuse value", Range(0, 3)) = 1
 
        _FurLength("Fur length", Range(0.0, 1)) = 0.5
        _CutOff("Alpha cutoff", Range(0, 1)) = 0.5
        _Blur("Blur", Range(0, 1)) = 0.5
        _Thickness("Thickness", Range(0, 0.5)) = 0
    }
 
        CGINCLUDE
 
        fixed _Diffuse;
    inline fixed4 LambertDiffuse(float3 worldNormal)
    {
        float3 lightDir = normalize(_WorldSpaceLightPos0.xyz);
        float NdotL = max(0.2, dot(worldNormal, lightDir));
        return NdotL*  _Diffuse;
    }
    
 
    ENDCG
 
        SubShader
    {
        Tags{ "RenderType" = "Transparent"   "Queue" = "Transparent"  "LightMode" = "ForwardBase" }
        ZWrite Off
        Blend SrcAlpha OneMinusSrcAlpha
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.05
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.10
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.15
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.20
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.25
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.30
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.35
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.40
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.45
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.50
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.55
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.60
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.65
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.70
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.75
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.80
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.85
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.90
#include "FurHelper.cginc"
        ENDCG
    }
 
        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define FURSTEP 0.95
#include "FurHelper.cginc"
        ENDCG
    }
    }
}