// 案例 20.2 / 20.3：完整的三平面映射——颜色 + 法线（四种法线混合方式可切换）
Shader "Cookbook/Ch20/Triplanar"
{
    Properties
    {
        _BaseMap ("Albedo", 2D) = "white" {}
        _BaseColor ("Tint", Color) = (1,1,1,1)
        [NoScaleOffset][Normal] _BumpMap ("Normal Map", 2D) = "bump" {}
        _BumpScale ("Normal Scale", Range(0, 2)) = 1
        _Tiling ("Tiling (1/m)", Float) = 0.5
        _Sharpness ("Blend Sharpness", Range(1, 32)) = 6
        [Enum(Swizzle,0,UDN,1,Whiteout,2,RNM,3)] _NormalMode ("Normal Blend", Float) = 3
        _Smoothness ("Smoothness", Range(0, 1)) = 0.3
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" "RenderPipeline"="UniversalPipeline" "Queue"="Geometry" }

        HLSLINCLUDE
        #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
        CBUFFER_START(UnityPerMaterial)
            float4 _BaseMap_ST;
            half4 _BaseColor;
            half _BumpScale;
            float _Tiling;
            float _Sharpness;
            float _NormalMode;
            half _Smoothness;
        CBUFFER_END
        ENDHLSL

        Pass
        {
            Name "ForwardLit"
            Tags { "LightMode"="UniversalForwardOnly" }   // 自定义表面混合，没有 GBuffer Pass：Deferred 下也走前向
            HLSLPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma multi_compile _ _MAIN_LIGHT_SHADOWS _MAIN_LIGHT_SHADOWS_CASCADE _MAIN_LIGHT_SHADOWS_SCREEN
            #pragma multi_compile _ _ADDITIONAL_LIGHTS_VERTEX _ADDITIONAL_LIGHTS
            #pragma multi_compile_fragment _ _ADDITIONAL_LIGHT_SHADOWS
            #pragma multi_compile_fragment _ _SHADOWS_SOFT _SHADOWS_SOFT_LOW _SHADOWS_SOFT_MEDIUM _SHADOWS_SOFT_HIGH
            #pragma multi_compile _ _FORWARD_PLUS
            #pragma multi_compile_fog
            #pragma multi_compile_instancing

            #include "Assets/Cookbook/Ch20/TerrainCommon.hlsl"

            TEXTURE2D(_BaseMap); SAMPLER(sampler_BaseMap);
            TEXTURE2D(_BumpMap); SAMPLER(sampler_BumpMap);

            struct Attributes
            {
                float4 positionOS : POSITION;
                float3 normalOS   : NORMAL;
                UNITY_VERTEX_INPUT_INSTANCE_ID
            };
            struct Varyings
            {
                float4 positionCS : SV_POSITION;
                float3 positionWS : TEXCOORD0;
                half3  normalWS   : TEXCOORD1;
                half   fogFactor  : TEXCOORD2;
            };

            Varyings vert(Attributes v)
            {
                Varyings o;
                UNITY_SETUP_INSTANCE_ID(v);
                VertexPositionInputs p = GetVertexPositionInputs(v.positionOS.xyz);
                o.positionCS = p.positionCS;
                o.positionWS = p.positionWS;
                o.normalWS = TransformObjectToWorldNormal(v.normalOS);
                o.fogFactor = ComputeFogFactor(p.positionCS.z);
                return o;
            }

            half4 frag(Varyings i) : SV_Target
            {
                half3 n = normalize(i.normalWS);
                float3 w = TriplanarWeights(n, _Sharpness);
                TriplanarUV uv = GetTriplanarUV(i.positionWS, n, _Tiling);

                half3 albedo = SampleTriplanar(TEXTURE2D_ARGS(_BaseMap, sampler_BaseMap), uv, w).rgb * _BaseColor.rgb;
                half3 normalWS = TriplanarNormalWS(TEXTURE2D_ARGS(_BumpMap, sampler_BumpMap), uv, w, n, _BumpScale, (int)_NormalMode);

                return Ch20ShadePBR(i.positionWS, normalWS, i.positionCS, albedo, 0, _Smoothness, 1, i.fogFactor);
            }
            ENDHLSL
        }

        Pass
        {
            Name "ShadowCaster"
            Tags { "LightMode"="ShadowCaster" }
            ZWrite On ZTest LEqual ColorMask 0
            HLSLPROGRAM
            #pragma vertex Ch20ShadowVert
            #pragma fragment Ch20EmptyFrag
            #pragma multi_compile_instancing
            #pragma multi_compile_vertex _ _CASTING_PUNCTUAL_LIGHT_SHADOW
            #include "Assets/Cookbook/Ch20/ShadowDepthPasses.hlsl"
            ENDHLSL
        }
        Pass
        {
            Name "DepthOnly"
            Tags { "LightMode"="DepthOnly" }
            ZWrite On ColorMask R
            HLSLPROGRAM
            #pragma vertex Ch20DepthVert
            #pragma fragment Ch20EmptyFrag
            #pragma multi_compile_instancing
            #include "Assets/Cookbook/Ch20/ShadowDepthPasses.hlsl"
            ENDHLSL
        }
        Pass
        {
            Name "DepthNormals"
            Tags { "LightMode"="DepthNormals" }
            ZWrite On
            HLSLPROGRAM
            #pragma vertex Ch20DepthVert
            #pragma fragment Ch20DepthNormalsFrag
            #pragma multi_compile_instancing
            #include "Assets/Cookbook/Ch20/ShadowDepthPasses.hlsl"
            ENDHLSL
        }
    }
}