遮罩纹理(mask texture)
遮罩允许我们可以保护某些区域,使他们免于修改。一般流程是:通过采样得到遮罩纹理的素纹值,然后使用其中一个或几个通道的值(如r)和某种表面属性相乘,这样当该通道的值为0时,可以保证表面不受这种属性的影响。遮罩纹理可以像素级别的控制模型表面的各种性质。
例如控制表面高光:
Shader "Unlit/MaskTexure"
{
Properties
{
_Color("Color",Color)=(1.0,1.0,1.0,1.0) //用来控制漫反射
_Specular("Specular",Color)=(1.0,1.0,1.0,1.0)
_Gloss("Gloss",Range(30.0,100.0)) = 30.0
_MainTex("Main Tex",2D)="white"{}
_BumpTex("Bump Tex",2D)="Bump"{}
_BumpTexScale("Bump Scale",float) = -0.8
_SpecularMaskTex("Specular Mask Tex",2D)="white"{}
_SpecularMaskScale("Specular Mask Scale",float) = 1.0
}
SubShader
{
Pass
{
Tags{"LightModel"="ForwardBase"}
CGPROGRAM
#include "Lighting.cginc"
#include "UnityCG.cginc"
#pragma vertex vert
#pragma fragment frag
fixed4 _Color;
fixed4 _Specular;
float _Gloss;
sampler2D _MainTex;
float4 _MainTex_ST;
sampler2D _BumpTex;
float4 _BumpTex_ST;
float _BumpTexScale;
sampler2D _SpecularMaskTex;
float _SpecularMaskScale;
/*
#define MODEL_2_TANGENT_ROTATION \
fixed3 binormal = cross(normalize(v.normal),normalize(v.tangent.xyz)) * v.tangent.w; \
float3x3 rotation = float3x3(v.tangent.xyz,binormal,v.noraml)
*/
struct a2v
{
float4 vertex:POSITION;
float3 normal:NORMAL;
float4 tangent:TANGENT;
float4 texcoord:TEXCOORD0;
};
struct v2f
{
float4 pos:SV_POSITION;
float3 tangentLightDir:TEXCOORD0;
float3 tangentViewDir:TEXCOORD1;
float4 uv:TEXCOORD2;
};
v2f vert(a2v v)
{
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);
o.uv.xy = v.texcoord.xy * _MainTex_ST.xy + _MainTex_ST.zw;
o.uv.zw = v.texcoord.xy * _BumpTex_ST.xy + _BumpTex_ST.zw;
TANGENT_SPACE_ROTATION;
o.tangentLightDir = mul(rotation,ObjSpaceLightDir(v.vertex));
o.tangentViewDir = mul(rotation,ObjSpaceViewDir(v.vertex));
return o;
}
fixed4 frag(v2f i):SV_TARGET
{
float3 tangentLightDir = normalize(i.tangentLightDir);
float3 tangentViewDir = normalize(i.tangentViewDir);
fixed3 packedNormal = UnpackNormal(tex2D(_BumpTex,i.uv.zw));
packedNormal.xy *= _BumpTexScale;
packedNormal.z = sqrt(1-saturate(dot(packedNormal.xy,packedNormal.xy)));
float albedo = tex2D(_MainTex,i.uv.xy).rgb * _Color.rgb;
fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.rgb * albedo;
fixed3 diffuse = _LightColor0.rgb * albedo * saturate(dot(packedNormal,tangentLightDir));
fixed specuarlMask = tex2D(_SpecularMaskTex,i.uv.xy).r * _SpecularMaskScale;
fixed halfNormal = normalize(tangentLightDir+tangentViewDir);
fixed3 specular = _LightColor0.rgb * _Specular * pow(saturate(dot(packedNormal,halfNormal)),_Gloss)*specuarlMask;
return fixed4(ambient+diffuse+specular,1.0);
}
ENDCG
}
}
Fallback "specular"
}
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