//Created by Wans Wu
//2025,05,08
Shader "WansShader/Decal/Unlit"
{
    Properties
    {
        [Enum(UnityEngine.Rendering.CullMode)]_CullMode("剔除模式", Float) = 2.0
        [Enum(UnityEngine.Rendering.CompareFunction)]_ZTes("Ztest", Float) = 4.0
        _Tiliing ("全局Tiliing", vector) = (1, 1, 0, 0)
        [Main(PBRIntput, _, off, off)] _PBRIntput ("基础属性", Float) = 1
        [Tex(PBRIntput,_BaseColor)][MainTexture] _BaseMap("Base贴图", 2D) = "white" {}
        [HideInInspector][MainColor][HDR] _BaseColor("Base颜色", Color) = (1,1,1,1)
        [Sub(PBRIntput)] _AddColor("叠加 颜色", Color) = (0,0,0,0)
        [Sub(PBRIntput)] _Intensity("亮度", Float) =1.0
        [Sub(PBRIntput)] _Opacity("透明度", Range(0.0, 1.0)) =1.0
        [Sub(PBRIntput)] _Fade("Fade", Range(0.0, 1.0)) =1.0
        [Main(Emission, _EMISSION, off)] _Emission ("发光", Float) = 0
        [Tex(Emission,_EmissionColor)]_EmissionMap("发光贴图", 2D) = "white" {}
        [HideInInspector][HDR]_EmissionColor("发光颜色", Color) = (0,0,0,1)
        [Sub(Emission)]_EmissionStrength("发光强度", Range(0.0, 1.0)) =1.0
    }

    SubShader
    {
        Tags{"RenderType" = "Transparent" "Queue"="Transparent" "RenderPipeline" = "UniversalPipeline" }
        Pass
        {
            Tags{"LightMode" = "UniversalForward"}
            Cull[_CullMode]
            ZWrite Off
            ZTest [_ZTes]
            
            Blend SrcAlpha OneMinusSrcAlpha
            HLSLPROGRAM
            #pragma target 3.5
            #pragma shader_feature_local _EMISSION
            #pragma multi_compile_fog

            #pragma vertex LitPassVertex
            #pragma fragment LitPassFragment
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/UnityInput.hlsl"
            #include  "Packages/com.unity.render-pipelines.universal/ShaderLibrary/DeclareDepthTexture.hlsl"
            struct Attributes
            {
                float4 positionOS   : POSITION;
                float2 texcoord     : TEXCOORD0;
                UNITY_VERTEX_INPUT_INSTANCE_ID
            };
            struct Varyings
            {
                float2 uv                       : TEXCOORD0;
                float3 positionWS               : TEXCOORD1;
                float4 positionCS               : SV_POSITION;
                float4 positionOS               :TEXCOORD2;
                UNITY_VERTEX_OUTPUT_STEREO 
            };
            
            TEXTURE2D(_BaseMap);
            SAMPLER(sampler_BaseMap);
            #if defined (_EMISSION)
            TEXTURE2D(_EmissionMap);
            SAMPLER(sampler_EmissionMap);
            #endif
            CBUFFER_START(UnityPerMaterial)
            float4 _ReflectionCubeMap_HDR;
            half4 _BaseColor;
            half4 _AddColor;
            half4 _EmissionColor;
            half _EmissionStrength;
            half4 _Tiliing;
            half _Opacity;
            half _Fade;
            half _Intensity;
            CBUFFER_END
            float3 ReconstructWorldPos( float2 ScreenUV, float rawdepth )
			{
				#if UNITY_REVERSED_Z
                real depth = rawdepth;
                #else
                real depth = lerp(UNITY_NEAR_CLIP_VALUE, 1, rawdepth);
                #endif
                float3 worldPos = ComputeWorldSpacePosition(ScreenUV, depth, UNITY_MATRIX_I_VP);
                return worldPos;
			}

            float LinearStep(float Min,float Max,float Value)
            {
                return clamp((Value - Min) / (Max  - Min),0,1);
            }

            
            Varyings LitPassVertex(Attributes input)
            {
                Varyings output = (Varyings)0;
                UNITY_SETUP_INSTANCE_ID(input); 
                UNITY_TRANSFER_INSTANCE_ID(input, output); 
                UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(output); 
                VertexPositionInputs vertexInput = GetVertexPositionInputs(input.positionOS.xyz);
                output.uv = input.texcoord;
                output.positionWS = vertexInput.positionWS;
                output.positionCS = vertexInput.positionCS;
                output.positionOS = input.positionOS;
                return output;
            }
            
            float4 LitPassFragment(Varyings input) : SV_Target
            {
                UNITY_SETUP_INSTANCE_ID(input);
                UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(input);
                
                float4 posCS = TransformObjectToHClip(float4(input.positionOS.xyz,0));
            	float4 positionCSNDC = float4(posCS.xyz/ posCS.w,1.0);
                float4 screenPos =  ComputeScreenPos(positionCSNDC);
            	float screenDepth =  SampleSceneDepth(screenPos.xy);
                float3 ReconstPos = ReconstructWorldPos(screenPos.xy,screenDepth);
                float3 ReconstPosOS = TransformWorldToObject(float4(ReconstPos,0));
                
                float3 ReconstPosOSOffset = ReconstPosOS + half3(0,0.5,0);
                float3 PosStep = step(-0.5,ReconstPosOSOffset) * (1 - step(0.5,ReconstPosOSOffset));
                float BoundingBox = PosStep.x * PosStep.y * PosStep.z;

                
                float2 decaluv = (ReconstPosOS.xz + 0.5 ) *  _Tiliing.xy + _Tiliing.zw;
              
                half decalFade = LinearStep(0,_Fade,-ReconstPosOS.y);
                
                float4 BaseColorAlpha = SAMPLE_TEXTURE2D(_BaseMap,sampler_BaseMap,decaluv) ;
                float3 BaseColor = BaseColorAlpha.rgb *_BaseColor.rgb * _Intensity + _AddColor.rgb;
                  float4 EmissonMap = 0;
                #if defined (_EMISSION)
                   EmissonMap = (SAMPLE_TEXTURE2D(_EmissionMap,sampler_EmissionMap,decaluv)* _EmissionColor  )* _EmissionStrength;
                #else
                   EmissonMap = half4(0,0,0,0);
                #endif
                float4 EmissonColor = EmissonMap;
                float csz = input.positionCS.z * input.positionCS.w; 
                real fogFactor = ComputeFogFactor(csz);
                half finalAlpha = saturate(BaseColorAlpha.a  * _Opacity * BoundingBox * decalFade);
                float4 color = half4(BaseColor + EmissonColor.rgb ,finalAlpha);
                color.rgb = MixFog(color.rgb,fogFactor) ;
               return color;
                
            }
             ENDHLSL
            }
    }
    FallBack "Hidden/Universal Render Pipeline/FallbackError"
    CustomEditor "LWGUI.LWGUI"
}