// SimpleWeaponHighlight.shader
// 基于URP/Lit的简化版，仅添加自发光强度控制
Shader "URP/Weapon/SimpleHighlight"
{
    Properties
    {
        // 基础属性
        [MainTexture] _BaseMap("Base Texture", 2D) = "white" {}
        [MainColor] _BaseColor("Base Color", Color) = (1,1,1,1)
        
        // 材质属性
        _Metallic("Metallic", Range(0, 1)) = 0.5
        _Smoothness("Smoothness", Range(0, 1)) = 0.5
        
        // 核心：自发光强度控制
        [HDR] _EmissionColor("Emission Color", Color) = (1,1,1,1)
        _EmissionStrength("Emission Strength", Range(0, 10)) = 0.0
    }
    
    SubShader
    {
        Tags 
        { 
            "RenderType"="Opaque" 
            "RenderPipeline"="UniversalPipeline"
            "Queue"="Geometry"
        }
        
        // 主光照通道
        Pass
        {
            Name "ForwardLit"
            Tags { "LightMode" = "UniversalForward" }
            
            HLSLPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            
            // URP核心库
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"
            #include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Color.hlsl"
            
            // 纹理和采样器
            TEXTURE2D(_BaseMap);
            SAMPLER(sampler_BaseMap);
            
            // 材质属性缓冲区
            CBUFFER_START(UnityPerMaterial)
                float4 _BaseMap_ST;
                float4 _BaseColor;
                float _Metallic;
                float _Smoothness;
                float4 _EmissionColor;
                float _EmissionStrength;
            CBUFFER_END
            
            // 顶点输入结构
            struct Attributes
            {
                float4 positionOS : POSITION;
                float3 normalOS : NORMAL;
                float2 texcoord : TEXCOORD0;
            };
            
            // 顶点输出结构
            struct Varyings
            {
                float2 uv : TEXCOORD0;
                float3 normalWS : TEXCOORD1;
                float3 viewDirWS : TEXCOORD2;
                float4 positionHCS : SV_POSITION;
            };
            
            // 顶点着色器
            Varyings vert(Attributes input)
            {
                Varyings output;
                
                // 顶点位置变换
                VertexPositionInputs vertexInput = GetVertexPositionInputs(input.positionOS.xyz);
                output.positionHCS = vertexInput.positionCS;
                
                // 法线变换
                VertexNormalInputs normalInput = GetVertexNormalInputs(input.normalOS);
                output.normalWS = normalInput.normalWS;
                
                // 视线方向
                output.viewDirWS = GetWorldSpaceViewDir(vertexInput.positionWS);
                
                // 纹理坐标
                output.uv = TRANSFORM_TEX(input.texcoord, _BaseMap);
                
                return output;
            }
            
            // 片元着色器
            half4 frag(Varyings input) : SV_Target
            {
                // 采样基础纹理
                half4 baseColor = SAMPLE_TEXTURE2D(_BaseMap, sampler_BaseMap, input.uv) * _BaseColor;
                
                // 获取主光源
                Light mainLight = GetMainLight();
                
                // 基础光照计算（Lambert漫反射）
                float3 normalWS = normalize(input.normalWS);
                float NdotL = saturate(dot(normalWS, mainLight.direction));
                float3 diffuse = baseColor.rgb * NdotL * mainLight.color;
                
                // 高光计算（简化版Blinn-Phong）
                float3 viewDirWS = normalize(input.viewDirWS);
                float3 halfDir = normalize(mainLight.direction + viewDirWS);
                float NdotH = saturate(dot(normalWS, halfDir));
                float specular = pow(NdotH, _Smoothness * 128.0) * _Metallic;
                float3 specularColor = specular * mainLight.color;
                
                // 自发光计算（核心）
                float3 emission = _EmissionColor.rgb * _EmissionStrength;
                
                // 最终颜色合成：基础光照 + 高光 + 自发光
                float3 finalColor = diffuse + specularColor + emission;
                
                return half4(finalColor, baseColor.a);
            }
            ENDHLSL
        }
        
        // 使用URP Lit的阴影和深度Pass，保持兼容性
        UsePass "Universal Render Pipeline/Lit/ShadowCaster"
        UsePass "Universal Render Pipeline/Lit/DepthOnly"
    }
    
    FallBack "Universal Render Pipeline/Lit"
}