遮罩紋理（mask texture）控制光照的強度鹰服，獲得更加細膩的效果，通過遮罩紋理控制光照揽咕。在制作地形材質(zhì)的時候混合多張圖片悲酷，遮罩紋理控制如何混合這些紋理。
通過采樣得到的紋素值與某種表面屬性相乘亲善，來更加精準的控制模型表面的各種屬性设易。
在代碼中添加了BumpMap來進行凹凸紋理效果，通過SpecularMask實現(xiàn)控制高光的光照

Shader "Unlit/MaskTexture"
{
    Properties{
        _Color ("Color Tint",Color) = (1,1,1,1)
        _MainTex("Main　Tex",2D) = "white" {}
        _BumpMap("Normal Map",2D) = "bump"{}
        _BumpScale("Bump Scale",Float) = 1.0
        _SpecularMask("Specular Mask",2D) = "white"{}
        _SpecularScale("Specular Scale",Float) = 1.0
        _Specular("Specular",Color) = (1,1,1,1)
        _Gloss("Gloss",Range(8.0,256)) = 20
    }
        SubShader{
        Pass{
            Tags{ "LightMode" = "ForwardBase"}
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "Lighting.cginc"

            fixed4 _Color;
            sampler2D _MainTex;
            float4 _MainTex_ST;
            sampler2D _BumpMap;
            float _BumpScale;
            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.xy = v.vertex.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 tangentLightDir = normalize(i.lightDir);
                fixed3 tangentViewDir = normalize(i.viewDir);
                fixed3 tangentNormal = UnpackNormal(tex2D(_BumpMap, i.uv));
                tangentNormal.xy *= _BumpScale;
                tangentNormal.z = sqrt(1.0 - saturate(dot(tangentNormal.xy, tangentNormal.xy)));

                fixed3 albedo = tex2D(_MainTex, i.uv).rgb * _Color.rgb;
                fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;
                fixed3 diffuse = _LightColor0.rgb * albedo * max(0, dot(tangentNormal, tangentLightDir));
                fixed3 halfDir = normalize(tangentLightDir + tangentViewDir);

                fixed specularMask = tex2D(_SpecularMask, i.uv).r * _SpecularScale;

                fixed3 specular = _LightColor0.rgb * specularMask * _Specular.rgb * pow(max(0, dot(halfDir, tangentNormal)), _Gloss);

                return fixed4(ambient + diffuse + specular, 1.0);
            }
            ENDCG
        }
        }
}

MaskTexture.PNG