Unity Shader學習：皮毛渲染

主要思路：将頂點延法線擠出，一層一層pass往外疊加形成毛發效果。

原文連結：https://blog.csdn.net/qq_24153371/article/details/81742337

噪聲圖：

cginc部分：

#include "Lighting.cginc"
#include "UnityCG.cginc"
#include "AutoLight.cginc"		

float4 _Color;
float4 _Specular;
float _Shininess;
sampler2D _MainTex;
float4 _MainTex_ST;
sampler2D _FurTex;
float4 _FurTex_ST;
float _FurLength;
float _FurDensity;
float _FurThinness;
float _FurShading;
float _RimPower;

struct v2f {
	float4 pos:SV_POSITION;
	float4 uv:TEXCOORD0;
	float3 worldNormal:TEXCOORD1;
	float3 worldPos:TEXCOORD2;
};

v2f vert_surface(appdata_base v) {
	v2f o;
	o.pos = UnityObjectToClipPos(v.vertex);
	o.uv.xy = TRANSFORM_TEX(v.texcoord, _MainTex);
	o.worldNormal = UnityObjectToWorldNormal(v.normal);
	o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
	return o;
}

//lambert+blinn-phone
float4 frag_surface(v2f i) :SV_Target{
	float3 worldNormal = normalize(i.worldNormal);
	float3 worldLight = normalize(_WorldSpaceLightPos0.xyz);
	float3 worldView = normalize(_WorldSpaceCameraPos.xyz - i.worldPos.xyz);
	float3 worldHalf = normalize(worldView + worldLight);
	float3 albedo = tex2D(_MainTex, i.uv.xy).rgb *_Color;	
	float3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;
	float3 diffuse = _LightColor0.rgb*albedo*saturate(dot(worldNormal, worldLight));
	float3 specular = _LightColor0.rgb*_Specular.rgb*pow(saturate(dot(worldNormal, worldHalf)), _Shininess);
	float3 color = ambient + diffuse + specular;
	return float4(color, 1.0);
}

v2f vert_base(appdata_base v) {
	v2f o;
	//每個pass延法線擠出頂點
	float3 P = v.vertex.xyz + v.normal*_FurLength*FURSTEP;
	o.pos = UnityObjectToClipPos(float4(P, 1.0));
	o.uv.xy = TRANSFORM_TEX(v.texcoord, _MainTex);
	o.uv.zw = TRANSFORM_TEX(v.texcoord, _FurTex);
	o.worldNormal = UnityObjectToWorldNormal(v.normal);
	o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
	return o;
}

float4 frag_base(v2f i) :SV_Target{
	float3 worldNormal = normalize(i.worldNormal);
	float3 worldLight = normalize(_WorldSpaceLightPos0.xyz);
	float3 worldView = normalize(_WorldSpaceCameraPos.xyz - i.worldPos.xyz);
	float3 worldHalf = normalize(worldView + worldLight);
	float3 albedo = tex2D(_MainTex, i.uv.xy).rgb*_Color;
	//陰影：靠近根部顔色越暗
	albedo -= (pow(1 - FURSTEP, 3)) * _FurShading;	
	//邊緣光：邊緣毛發可能受油光影響
	float rim = 1.0 - saturate(dot(worldView, worldNormal));
	albedo += float3(1, 1, 1)*pow(rim, _RimPower);
	float3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz*albedo;
	float3 diffuse = _LightColor0.rgb*albedo*saturate(dot(worldNormal, worldLight));
	float3 specular = _LightColor0.rgb*_Specular.rgb*pow(saturate(dot(worldNormal, worldHalf)), _Shininess);
	float3 color = ambient + diffuse + specular;
	//修改tile改變毛發細度
	float3 noise = tex2D(_FurTex, i.uv.zw*_FurThinness).rgb;
	//越到尾部毛發越細越少
	float alpha = clamp(noise - (FURSTEP*FURSTEP)*_FurDensity, 0, 1);
	return float4(color, alpha);
}

           

shader部分：

Shader "Unlit/Fur"
{
	Properties
	{
		_Color("Color",Color)=(1,1,1,1)
		_Specular("Specular",Color)=(1,1,1,1)
		_Shininess("Shininess",Range(0,20))=0.0
		_MainTex("MainTex",2D)="white"{}
	    _FurTex("FurTex",2D)="white"{}
		_FurLength("FurLength",float)=0.0
		_FurDensity("FurDensity",Range(0,2))=0.11
		_FurThinness("FurThinness",Range(0.01,10))=1
		_FurShading("FurShading",Range(0.0,1))=0.25
		_RimPower("RimPower",Range(0,20))=1
	}

	SubShader{

			Tags {"RenderType" = "Transparent" "Queue" = "Transparent"}
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass {
				CGPROGRAM
				#define FURSTEP 0.00
				#pragma	vertex vert_surface
				#pragma fragment frag_surface
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags {"RenderType" = "Transparent" "Queue" = "Transparent"}
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass {
				CGPROGRAM
				#define FURSTEP 0.05
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags {"RenderType" = "Transparent" "Queue" = "Transparent"}
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass {
				CGPROGRAM
				#define FURSTEP 0.10
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags {"RenderType" = "Transparent" "Queue" = "Transparent"}
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass {
				CGPROGRAM
				#define FURSTEP 0.15
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags {"RenderType" = "Transparent" "Queue" = "Transparent"}
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass {
				CGPROGRAM
				#define FURSTEP 0.20
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags {"RenderType" = "Transparent" "Queue" = "Transparent"}
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass {
				CGPROGRAM
				#define FURSTEP 0.25
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags {"RenderType" = "Transparent" "Queue" = "Transparent"}
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass {
				CGPROGRAM
				#define FURSTEP 0.30
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags {"RenderType" = "Transparent" "Queue" = "Transparent"}
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass {
				CGPROGRAM
				#define FURSTEP 0.35
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags{ "RenderType" = "Transparent" "Queue" = "Transparent" }
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass{
				CGPROGRAM
				#define FURSTEP 0.40
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags{ "RenderType" = "Transparent" "Queue" = "Transparent" }
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass{
				CGPROGRAM
				#define FURSTEP 0.45
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags{ "RenderType" = "Transparent" "Queue" = "Transparent" }
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass{
				CGPROGRAM
				#define FURSTEP 0.50
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags{ "RenderType" = "Transparent" "Queue" = "Transparent" }
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass{
				CGPROGRAM
				#define FURSTEP 0.55
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags{ "RenderType" = "Transparent" "Queue" = "Transparent" }
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass{
				CGPROGRAM
				#define FURSTEP 0.60
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags{ "RenderType" = "Transparent" "Queue" = "Transparent" }
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass{
				CGPROGRAM
				#define FURSTEP 0.65
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags{ "RenderType" = "Transparent" "Queue" = "Transparent" }
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass{
				CGPROGRAM
				#define FURSTEP 0.70
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags{ "RenderType" = "Transparent" "Queue" = "Transparent" }
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass{
				CGPROGRAM
				#define FURSTEP 0.75
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags{ "RenderType" = "Transparent" "Queue" = "Transparent" }
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass{
				CGPROGRAM
				#define FURSTEP 0.80
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags{ "RenderType" = "Transparent" "Queue" = "Transparent" }
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass{
				CGPROGRAM
				#define FURSTEP 0.85
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags{ "RenderType" = "Transparent" "Queue" = "Transparent" }
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass{
				CGPROGRAM
				#define FURSTEP 0.90
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags{ "RenderType" = "Transparent" "Queue" = "Transparent" }
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass{
				CGPROGRAM
				#define FURSTEP 0.95
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}

			Tags{ "RenderType" = "Transparent" "Queue" = "Transparent" }
			Cull Off
			Blend SrcAlpha OneMinusSrcAlpha
			Pass{
				CGPROGRAM
				#define FURSTEP 0.1
				#pragma	vertex vert_base
				#pragma fragment frag_base
				#include "FurCGInclude.cginc"
				ENDCG
			}
	}
}