#pragma kernel MaterialFlagsGen_Write		MATERIALFLAGSGEN=MaterialFlagsGen_Write
#pragma kernel MaterialFlagsGen_Or			MATERIALFLAGSGEN=MaterialFlagsGen_Or		USE_OR

// #pragma enable_d3d11_debug_symbols

#include "ShaderLibrary/common.hlsl"
#include "ShaderBase.hlsl"
#include "TilePass.cs.hlsl"

#define UNITY_MATERIAL_LIT // Need to be define before including Material.hlsl
#include "../../Material/Material.hlsl" // This includes Material.hlsl
#include "../../Lighting/LightDefinition.cs.hlsl"

#define USE_MATERIAL_FEATURE_FLAGS
#define NR_THREADS	64

CBUFFER_START(UnityMaterialFlags)
uint2 g_viDimensions;
uint g_BaseFeatureFlags;
CBUFFER_END

groupshared uint ldsFeatureFlags;
RWStructuredBuffer<uint> g_TileFeatureFlags;

TEXTURE2D(_StencilTexture);               // DXGI_FORMAT_R8_UINT is not supported by Unity

[numthreads(NR_THREADS, 1, 1)]
void MATERIALFLAGSGEN(uint threadID : SV_GroupIndex, uint3 u3GroupID : SV_GroupID)
{
	uint2 tileIDX = u3GroupID.xy;

	uint iWidth = g_viDimensions.x;
	uint iHeight = g_viDimensions.y;
	uint nrTilesX = (iWidth+15)/16;

	uint2 viTilLL = 16*tileIDX;

	float2 invScreenSize = float2(1.0f / iWidth, 1.0f / iHeight);

	if (threadID == 0)
	{
		ldsFeatureFlags = 0;
	}
	GroupMemoryBarrierWithGroupSync();

	uint materialFeatureFlags = g_BaseFeatureFlags; // Contain all lightFeatures or 0 (depends if we enable light classification or not)
	[unroll]
	for(int i = 0; i < 4; i++)
	{
		int idx = i * NR_THREADS + threadID;
		uint2 uCrd = min( uint2(viTilLL.x + (idx & 0xf), viTilLL.y + (idx >> 4)), uint2(iWidth - 1, iHeight - 1));

		if (UnpackByte(LOAD_TEXTURE2D(_StencilTexture, uCrd).r) != STENCILLIGHTINGUSAGE_NO_LIGHTING) // This test is we are the sky/background or not
		{
			PositionInputs posInput = GetPositionInput(uCrd, invScreenSize);
            materialFeatureFlags |= MATERIAL_FEATURE_FLAGS_FROM_GBUFFER(posInput.positionSS);
		}
	}

	InterlockedOr(ldsFeatureFlags, materialFeatureFlags);	//TODO: driver might optimize this or we might have to do a manual reduction
	GroupMemoryBarrierWithGroupSync();

	if(threadID == 0)
	{
#ifdef USE_OR
		g_TileFeatureFlags[tileIDX.y * nrTilesX + tileIDX.x] |= ldsFeatureFlags;
#else // Use in case we have disabled light classification
		g_TileFeatureFlags[tileIDX.y * nrTilesX + tileIDX.x] = ldsFeatureFlags;
#endif
	}
}