【Unity】ShaderLab-3_4-遮罩纹理

/**********
*
* 作者   :   Quaye
* 时间   :   2018.06.06
*
* 描述   :     遮罩纹理
*
**/
Shader "Quaye/_MaskTexture" 
{
    Properties
    {
        _Color("Color",Color)               = (1,1,1,1)
        _MainTex("MainTex",2D)              = "white"{}
        _BumpScale("NormalMap",float)       =  1
        _BumpMap("BumpMap",2D)              = "bump"{}
        _SpecularMask("SpecularMask",2D)    = "white"{}
        _SpecularScale("SpeculerScale",float)=1
        _Specular("Specular",Color)         = (1,1,1,1)
        _Gloss("Gloss",Range(8,256))        = 20
    }   

    SubShader
    {
        Pass
        {
            Tags{"LightMode" = "ForwardBase"}

            CGPROGRAM
            #pragma vertex      vert 
            #pragma fragment    frag 

            #include "Lighting.cginc"

            fixed4      _Color;
            sampler2D   _MainTex;
            float4      _MainTex_ST;
            float       _BumpScale;
            sampler2D   _BumpMap;
            sampler2D   _SpecularMask;
            float       _SpecularScale;
            fixed4      _Specular;
            float       _Gloss;

            struct a2v
            {
                float4 vertex   : POSITION;
                float3 normal   : NORMAL;
                float4 tangent  : TANGENT;
                float4 texcoord : TEXCOORD0;
            };
            struct v2f
            {
                float4 pos      : SV_POSITION;
                float2 uv       : TEXCOORD0;
                float3 lightDir : TEXCOORD1;
                float3 viewDir  : TEXCOORD2;
            };

            v2f vert (a2v v)
            {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.uv  = v.texcoord.xy * _MainTex_ST.xy + _MainTex_ST.zw;
                TANGENT_SPACE_ROTATION;
                o.lightDir = mul(rotation,ObjSpaceLightDir(v.vertex)).xyz;
                o.viewDir = mul(rotation,ObjSpaceViewDir(v.vertex)).xyz;
                return o;
            }

            fixed4 frag (v2f i) :SV_TARGET
            {
                fixed3 tL = normalize(i.lightDir);
                fixed3 tV = normalize(i.viewDir);
                fixed3 tN ;
                tN.xy = UnpackNormal(tex2D(_BumpMap,i.uv)) * _BumpScale;
                tN.z = sqrt(1 - saturate(dot(tN.xy,tN.xy)));

                fixed3 albedo  = tex2D(_MainTex,i.uv).rgb * _Color.rgb;
                fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;
                fixed3 diffuse = _LightColor0.rgb * albedo * saturate(dot(tL,tN));

                // 遮罩纹理采样，作用于高光反射
                fixed3 h = normalize(tL + tV);
                fixed4 specularMask = tex2D(_SpecularMask,i.uv)*_SpecularScale.r;
                fixed3 specular = _LightColor0.rgb * _Specular * pow(saturate(dot(h,tN)),_Gloss) * specularMask;

                return fixed4(ambient + diffuse + specular,1);
            }

            ENDCG
        }
    }
}