CG代码 雪景补充

Shader "Custom/snowMaterial"
{
    Properties
    {
        _Color ("Color", Color) = (1,1,1,1)
        _MainTex ("Albedo (RGB)", 2D) = "white" {}   
        _NormalTex("NormalTex",2D)="bump"{}
        _SnowTex("SnowTex",2D)="white"{}
        _SnowDir("SnowDir",vector)=(0,1,0,0)
        _SnowAmount("SnowAmount",Range(0,2))=1
        _SnowNormal("SnowNormal",2D)="bump"{}

        
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 200

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

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

        sampler2D _MainTex;
        sampler2D _NormalTex;
        sampler2D _SnowTex;
        sampler2D _SnowNormal;
         struct Input
        {
            float2 uv_MainTex;
            float2 uv_NormalTex;
            float2 uv_SnowTex;
            float2 uv_SnowNormal;
            float3 worldNormal;
            INTERNAL_DATA
        };

        half _Glossiness;
        half _Metallic;
        half _SnowAmount;
        fixed4 _Color;
        float4 _SnowDir;
        // 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)
        {   
            float3 normalTex=UnpackNormal(tex2D(_NormalTex,IN.uv_NormalTex));
            float3 SnowNormal=UnpackNormal(tex2D(_SnowNormal,IN.uv_SnowNormal));
            fixed3 wNormal=WorldNormalVector(IN,(0,0,1));//计算顶点的世界法线
            // Albedo comes from a texture tinted by color
            fixed3 finalNoraml=lerp(normalTex,SnowNormal,saturate(dot(wNormal,_SnowDir.xyz))*_SnowAmount);
            o.Normal=finalNoraml;
           
            fixed3 fwNormal=WorldNormalVector(IN,finalNoraml);
            float lerpVal=saturate(dot(fwNormal,_SnowDir.xyz ));

            fixed4 c =lerp( tex2D (_MainTex, IN.uv_MainTex) * _Color,tex2D(_SnowTex,IN.uv_SnowTex),lerpVal*_SnowAmount);

            o.Albedo = c.rgb;
            // Metallic and smoothness come from slider variables
           
            o.Smoothness = _Glossiness;
            o.Alpha = c.a;
        }
        ENDCG
    }
    FallBack "Diffuse"
}