// Created by Wans Wu
// Modified: Convert to Lit, support darker blending, alpha mask
Shader "WansShader/Decal/Lit_test"
{
    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(PBRInput, _, off, off)] _PBRInput("基础属性", Float) = 1
        [Tex(PBRInput,_BaseColor)][MainTexture]_BaseMap("Base贴图", 2D) = "white" {}
        [HideInInspector][MainColor][HDR]_BaseColor("Base颜色", Color) = (1,1,1,1)
        [Sub(PBRInput)]_AddColor("叠加颜色", Color) = (0,0,0,0)
        [Sub(PBRInput)]_Opacity("透明度", Range(0.0, 1.0)) = 1.0
        [Sub(PBRInput)]_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
        _AlphaMask("遮罩贴图", 2D) = "white" {}
    }

        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);
            TEXTURE2D(_AlphaMask); SAMPLER(sampler_AlphaMask);
            #if defined (_EMISSION)
            TEXTURE2D(_EmissionMap); SAMPLER(sampler_EmissionMap);
            #endif

            CBUFFER_START(UnityPerMaterial)
            float4 _BaseColor;
            float4 _AddColor;
            float4 _EmissionColor;
            float4 _Tiliing;
            float _Opacity;
            float _Fade;
            float _EmissionStrength;
            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
                return ComputeWorldSpacePosition(ScreenUV, depth, UNITY_MATRIX_I_VP);
            }

            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 screenPos = ComputeScreenPos(posCS / posCS.w);
                float screenDepth = SampleSceneDepth(screenPos.xy);
                float3 worldPos = ReconstructWorldPos(screenPos.xy, screenDepth);
                float3 localPos = TransformWorldToObject(float4(worldPos, 1)).xyz + float3(0, 0.5, 0);

                float3 inBox = step(-0.5, localPos) * (1 - step(0.5, localPos));
                float boxMask = inBox.x * inBox.y * inBox.z;

                float2 uv = (localPos.xz - float2(-0.5, -0.5)) * _Tiliing.xy + _Tiliing.zw;
                float fade = LinearStep(0, _Fade, -localPos.y);

                float4 baseCol = SAMPLE_TEXTURE2D(_BaseMap, sampler_BaseMap, uv);
                float alphaMask = SAMPLE_TEXTURE2D(_AlphaMask, sampler_AlphaMask, uv).r;
                float alpha = baseCol.a * _Opacity * boxMask * fade * alphaMask;
                float3 baseColor = baseCol.rgb * _BaseColor.rgb + _AddColor.rgb * baseCol.a;

                float3 emission = 0;
                #if defined (_EMISSION)
                emission = SAMPLE_TEXTURE2D(_EmissionMap, sampler_EmissionMap, uv).rgb * _EmissionColor.rgb * _EmissionStrength;
                #endif

                float csz = input.positionCS.z * input.positionCS.w;
                float fogFactor = ComputeFogFactor(csz);

                float4 color = float4(baseColor + emission, saturate(alpha));
                color.rgb = MixFog(color.rgb, fogFactor);
                return color;
            }
            ENDHLSL
        }
    }
        FallBack "Hidden/Universal Render Pipeline/FallbackError"
                CustomEditor "LWGUI.LWGUI"
}