Unity shader学习之遮罩纹理

什么是遮罩？

遮罩允许我们可以保护某些区域，使它们奂于某些修改。

例如下面的例子，使用遮罩来控制高光反射。

转载请注明出处：http://www.cnblogs.com/jietian331/p/7149182.html

使用的贴图，法线，遮罩纹理如下：

shader如下：

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

Shader "Custom/Mask Texture"
{
    Properties
    {
        _MainTexture("Main Texture", 2D) = "white" {}
        _NormalMap("Normal Map", 2D) = "bump" {}
        _MaskTexture("Mask Texture", 2D) = "white" {}
        _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 "UnityCG.cginc"
            #include "Lighting.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float4 uv : TEXCOORD0;
                float3 normal : NORMAL;
                float4 tangent : TANGENT;
                float4 color : COLOR;
            };

            struct v2f
            {
                float4 pos : SV_POSITION;
                float4 color : COLOR;
                float4 uv : TEXCOORD0;
                float3 tangentLight : TEXCOORD1;
                float3 tangentView : TEXCOORD2;
            };

            v2f vert(appdata v)
            {
                 v2f o;
                 o.pos = UnityObjectToClipPos(v.vertex);
                 o.uv = v.uv;
                 o.color = v.color;

                 float3 objLightDir = ObjSpaceLightDir(v.vertex);
                 float3 objViewDir = ObjSpaceViewDir(v.vertex);

                 TANGENT_SPACE_ROTATION;
                 o.tangentLight = mul(rotation, objLightDir);
                 o.tangentView = mul(rotation, objViewDir);
                 return o;
            }

            sampler2D _MainTexture;
            sampler2D _NormalMap;
            sampler2D _MaskTexture;
            float4 _Specular;
            float _Gloss;

            fixed4 frag(v2f i) : SV_TARGET
            {
                fixed3 tangentNormal = UnpackNormal(tex2D(_NormalMap, i.uv));
                fixed3 albedo = tex2D(_MainTexture, i.uv).rgb * i.color;
                fixed3 ambient = albedo * UNITY_LIGHTMODEL_AMBIENT.rgb;

                fixed3 diff = albedo * _LightColor0.rgb * max(0, dot(tangentNormal, i.tangentLight));

                fixed4 mask = tex2D(_MaskTexture, i.uv);
                fixed3 halfDir = normalize(i.tangentView + i.tangentLight);
                fixed3 spec = _Specular.rgb * _LightColor0.rgb * pow(max(0, dot(halfDir, tangentNormal)), _Gloss) * mask.r;

                fixed3 col = ambient + diff + spec;
                return fixed4(col, 1);
            }

            ENDCG
        }
    }

    Fallback "Specular"
}

使用和不使用遮罩的效果对比图如下：

使用遮罩：

不使用遮罩：

资源如下：

 http://files.cnblogs.com/files/jietian331/MaskTexture.rar