如何在此 splat 贴图着色器 (Unity3D) 中为每个通道添加单独的凹凸贴图？

如何解决如何在此 splat 贴图着色器 (Unity3D) 中为每个通道添加单独的凹凸贴图？

我有这个着色器，用于 Unity3D 中的 splat 贴图。这是一个弗兰肯斯坦式的怪物，我发现我终于开始工作了。问题是它没有在纹理上进行凹凸贴图的能力。

如果有人能告诉我要更改/添加到此着色器代码的哪些内容，使其能够为每个 RGBA 通道纹理提供单独的凹凸贴图，我将不胜感激。

Shader "Custom/Texture Splatting" {

Properties {
    _MainTex ("Splat Map",2D) = "white" {}
    [NoScaleOffset] _Texture1 ("R",2D) = "white" {}
    [NoScaleOffset] _Texture2 ("G",2D) = "white" {}
    [NoScaleOffset] _Texture3 ("B",2D) = "white" {}
    [NoScaleOffset] _Texture4 ("A",2D) = "white" {}
    _BumpMap1 ("BumpMapR",2D) = "bump" {}
    _BumpMap2 ("BumpMapG",2D) = "bump" {}
    _BumpMap3 ("BumpMapB",2D) = "bump" {}
    _BumpMap4 ("BumpMapA",2D) = "bump" {}
}

SubShader {

    Pass {
        CGPROGRAM

        #pragma vertex MyVertexProgram
        #pragma fragment MyFragmentProgram

        #include "UnityCG.cginc"

        sampler2D _MainTex;
        float4 _MainTex_ST;

        sampler2D _Texture1,_Texture2,_Texture3,_Texture4;

        struct VertexData {
            float4 position : POSITION;
            float2 uv : TEXCOORD0;
        };

        struct Interpolators {
            float4 position : SV_POSITION;
            float2 uv : TEXCOORD0;
            float2 uvSplat : TEXCOORD1;
        };

        Interpolators MyVertexProgram (VertexData v) {
            Interpolators i;
            i.position = UnityObjectToClipPos(v.position);
            i.uv = TRANSFORM_TEX(v.uv,_MainTex);
            i.uvSplat = v.uv;
            return i;
        }

        float4 MyFragmentProgram (Interpolators i) : SV_TARGET {
            float4 splat = tex2D(_MainTex,i.uvSplat);

            return
                tex2D(_Texture1,i.uv) * splat.r +
                tex2D(_Texture2,i.uv) * splat.g +
                tex2D(_Texture3,i.uv) * splat.b +
                tex2D(_Texture4,i.uv) * (1 - splat.r - splat.g - splat.b);
        }

        ENDCG
    }
}

}

解决方法

凹凸贴图通常用于影响光照在表面上的表现，增加表面不平坦的印象。然而，你上面的例子是一个没有光照的顶点着色器，它没有任何光照模拟，所以你不能只添加凹凸贴图，你首先需要把着色器变成一个光照着色器。我建议改用表面着色器。

如果您仍想使用顶点着色器进行照明，那是完全不同的研究。您可以在此 Unity thread 中看到有关此的一些解释，但除非您确实需要，否则我不会推荐它：

也就是说，这是我制作的一个 splat 表面着色器，它使用 splat 贴图来混合两个纹理并包括一个凹凸贴图。我建议您根据需要调整它（使用 4 个通道而不是 2 个），而不是尝试从头开始构建一个光照着色器。

Shader "Custom/TerrainTwoTexturesBlend" {
    Properties {
        _Color("Tint",Color) = (0.5,0.5,1)
        _MainTex("Albedo",2D) = "white" {}
        _BumpMap("Normal Map",2D) = "bump" {}

        _MainTex2("Albedo 2",2D) = "white" {}
        _BumpMap2("Normal Map 2",2D) = "bump" {}

        _Mask("Mask",2D) = "white" {}

        _Glossiness ("Smoothness",Range(0,1)) = 0.5
        _Specular ("Specular",1)) = 0.0
    }

    SubShader {
        Tags { 
            "Queue" = "Geometry-4"
            "RenderType" = "Opaque" 
            "PreviewType" = "Plane" 
            "ForceNoShadowCasting" = "True"
        }
        LOD 200

        ZWrite Off

        CGPROGRAM
        // Physically based Standard lighting model,and enable shadows on all light types
        #pragma surface surf StandardSpecular

        // Use shader model 3.0 target,to get nicer looking lighting
        #pragma target 3.0

        sampler2D _MainTex;
        sampler2D _BumpMap;

        sampler2D _MainTex2;
        sampler2D _BumpMap2;

        sampler2D _Mask;

        struct Input {
            float2 uv_MainTex: TEXCOORD0;
            float2 uv2_MainTex2: TEXCOORD2;
            float2 uv3_Mask: TEXCOORD1;
        };

        half _Glossiness;
        half _Specular;
        fixed4 _Color;

        // Add instancing support for this shader. You need to check 'Enable Instancing' on materials that use the shader.
        // See https://docs.unity3d.com/Manual/GPUInstancing.html for more information about instancing.
        // #pragma instancing_options assumeuniformscaling
        UNITY_INSTANCING_BUFFER_START(Props)
            // put more per-instance properties here
        UNITY_INSTANCING_BUFFER_END(Props)

        void surf (Input IN,inout SurfaceOutputStandardSpecular o) {
            float2 uvterrain1 = IN.uv_MainTex;
            float2 uvterrain2 = IN.uv2_MainTex2;
            float2 uvmask = IN.uv3_Mask;

            fixed4 c1 = tex2D(_MainTex,uvterrain1);
            fixed4 n1 = tex2D(_BumpMap,uvterrain1);

            fixed4 c2 = tex2D(_MainTex2,uvterrain2);
            fixed4 n2 = tex2D(_BumpMap2,uvterrain2);

            fixed4 m = tex2D(_Mask,uvmask);

            o.Albedo = _Color * (c1 * m.r + c2 * (1 - m.r));

            float3 fn1 = UnpackScaleNormal(n1,_BumpScale);
            float3 fn2 = UnpackScaleNormal(n2,_BumpScale2);
            o.Normal = fn1 * m.r + fn2 * (1 - m.r);

            // Metallic and smoothness come from slider variables
            o.Specular = _Specular;
            o.Smoothness = _Glossiness;
            o.Alpha = 1;
        }
        ENDCG
    }
    FallBack "Diffuse"
}