Shader "Hidden/OIT/LLOITRender"
{
    SubShader   
    {
        Tags
        {
            "RenderPipeline" = "UniversalPipeline"
        }
        Pass
        {
            ZTest Always
            ZWrite Off
            Cull Back
            Blend Off

            HLSLPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma target 5.0
            #pragma enable_d3d11_debug_symbols
            
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
            #include "LinkedListRendering.hlsl"

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            v2f vert(uint vertexID: SV_VertexID)
            {
                v2f o;
                float2 uv = float2((vertexID << 1) & 2, vertexID & 2);
                float4 pos = float4(uv * 2.0 - 1.0, UNITY_NEAR_CLIP_VALUE, 1.0);
                #ifdef UNITY_PRETRANSFORM_TO_DISPLAY_ORIENTATION
                pos = ApplyPretransformRotation(pos);
                #endif

                #if UNITY_UV_STARTS_AT_TOP
                uv = float2((vertexID << 1) & 2, 1.0 - (vertexID & 2));
                #endif

                o.vertex = pos;
                o.uv = uv;
                return o;
            }
   
            sampler2D _CameraColorTex_LLOIT;
            void frag(v2f input, out half4 col : SV_Target, uint uSampleIndex: SV_SampleIndex)
            {
                float4 screenColor = tex2D(_CameraColorTex_LLOIT, input.uv);
				col = renderLinkedList(screenColor, input.vertex.xy, uSampleIndex);
            }
            
            // gles、metal
            // void frag(v2f input, inout half4 col : SV_Target, uint uSampleIndex: SV_SampleIndex)
            // void frag(v2f input, inout half4 col : CoLoR, uint uSampleIndex: SV_SampleIndex)
            // {
            //     col.b = 0;
            //     // col = renderLinkedList(col, input.uv, uSampleIndex);
            // }
            			
    //         RWTexture2D<float4> _CameraColorTex; // dx12 运行同时作为 rtv uav,但是 Unity 无法设置 uav
    //         void frag(v2f input, out half4 col : SV_Target, uint uSampleIndex: SV_SampleIndex)
    //         {
    //             float4 screenColor = _CameraColorTex[uint2(input.uv * _ScreenParams.xy)]; // tex2D(_MainTex, input.uv);
				// col = renderLinkedList(screenColor, input.vertex.xy, uSampleIndex);
    //         }
            
            // vulkan、metal unity 无法同时读写(vk 扩展 VK_EXT_rasterization_order_attachment_access)
            // FRAMEBUFFER_INPUT_HALF(0);
            // void frag(v2f input, out half4 col : SV_Target, uint uSampleIndex: SV_SampleIndex)
            // {
            //     col =  LOAD_FRAMEBUFFER_INPUT(0, input.vertex.xy);
            //     // col = renderLinkedList(col, input.uv, uSampleIndex);
            // }
            ENDHLSL
        }
    }
}