#include "$ENGINE$\DeferredLightCommon.bslinc"

technique DeferredPointLight
{
	mixin DeferredLightCommon;

	#ifdef MSAA
	stencil
	{
		enabled = true;
		readmask = 0x80;
		
		#ifdef INSIDE_GEOMETRY
		back = { keep, keep, keep, eq };
		#else
		front = { keep, keep, keep, eq };
		#endif
		
		#ifdef MSAA_RESOLVE_0TH
		reference = 0;
		#else
		reference = 0x80;
		#endif
	};
	#endif
	
	code
	{
		#ifndef MSAA_RESOLVE_0TH
			#define MSAA_RESOLVE_0TH 0
		#endif		
	
		struct VStoFS
		{
			float4 position : SV_POSITION;
			float4 screenPos : TEXCOORD0;
		};

		struct VertexInput
		{
			float3 position : POSITION;
			uint vertexIdx : SV_VERTEXID;
		};
		
		VStoFS vsmain(VertexInput input)
		{
			VStoFS output;
			
			float3 worldPosition;
			uint numSides = gLightGeometry.x;
			if(numSides > 0) // Generate spot light geometry
			{
				uint numSlices = gLightGeometry.y;
				float radius = gLightGeometry.w;
				float angle = gLightSpotAnglesAndSqrdInvAttRadius.x;
			
				// Extra scale to ensure edges lie on the circle, not inside it
				// TODO - These can be precomputed
				float extraRadiusScale = 1.0f / cos(PI / (float)numSides);
				float angleTan = tan(angle);
				float height = radius / angleTan;
	
				uint sphereStartIdx = numSides * numSlices;
				// Cone vertices
				if (input.vertexIdx < sphereStartIdx)
				{
					uint sliceIdx = input.vertexIdx / numSides;
					uint sideIdx = input.vertexIdx % numSides;

					float curAngle = sideIdx * 2 * PI / (float)numSides;
					float sliceOffset = height * sliceIdx / (float)(numSlices - 1);
					float sliceRadius = sliceOffset * angleTan * extraRadiusScale;

					float4 localPos = float4(sliceRadius * cos(curAngle), 
						sliceRadius * sin(curAngle), -sliceOffset, 1.0f);
					worldPosition = (mul(gMatConeTransform, localPos)).xyz;
				}
				else // Sphere cap vertices
				{
					uint sphereVertexIdx = input.vertexIdx - sphereStartIdx;
					uint sliceIdx = sphereVertexIdx / numSides;
					uint sideIdx = sphereVertexIdx % numSides;

					float curAngle = sideIdx * 2 * PI / (float)numSides;
					float sliceOffset = radius * sliceIdx / (float)(numSlices - 1);
					float sliceRadius = sqrt(max(0.0f, radius * radius - sliceOffset * sliceOffset)) * extraRadiusScale;

					float4 localPos = float4(sliceRadius * cos(curAngle), 
						sliceRadius * sin(curAngle), -height - sliceOffset, 1.0f);
					worldPosition = (mul(gMatConeTransform, localPos)).xyz;
				}
			}
			else // Scale and position pre-generated sphere geometry
			{
				worldPosition = input.position * gLightGeometry.z + gLightPositionAndSrcRadius.xyz;
			}
			
			output.screenPos = mul(gMatViewProj, float4(worldPosition, 1));
			output.position = output.screenPos;
			
			return output;
		}			

		float4 fsmain(VStoFS input
			#if MSAA_COUNT > 1 && !MSAA_RESOLVE_0TH
			, uint sampleIdx : SV_SampleIndex
			#endif
			) : SV_Target0
		{
			float2 ndcPos = input.screenPos.xy / input.screenPos.w;
			uint2 pixelPos = NDCToScreen(ndcPos);
			
			#if MSAA_COUNT > 1
				#if MSAA_RESOLVE_0TH
					SurfaceData surfaceData = getGBufferData(pixelPos, 0);
				#else
					SurfaceData surfaceData = getGBufferData(pixelPos, sampleIdx);
				#endif
			#else
			SurfaceData surfaceData = getGBufferData(pixelPos);
			#endif	

			if(surfaceData.worldNormal.w > 0.0f)
			{
				// x, y are now in clip space, z, w are in view space
				// We multiply them by a special inverse view-projection matrix, that had the projection entries that effect
				// z, w eliminated (since they are already in view space)
				// Note: Multiply by depth should be avoided if using ortographic projection
				float4 mixedSpacePos = float4(ndcPos.xy * -surfaceData.depth, surfaceData.depth, 1);
				float4 worldPosition4D = mul(gMatScreenToWorld, mixedSpacePos);
				float3 worldPosition = worldPosition4D.xyz / worldPosition4D.w;

				float3 V = normalize(gViewOrigin - worldPosition);
				float3 N = surfaceData.worldNormal.xyz;
				float3 R = 2 * dot(V, N) * N - V;
				float3 specR = getSpecularDominantDir(N, R, surfaceData.roughness);
				
				float roughness2 = max(surfaceData.roughness, 0.08f);
				roughness2 *= roughness2;
				
				LightData lightData = getLightData();
				
				#if MSAA_COUNT > 1
					#if MSAA_RESOLVE_0TH
						float occlusion = gLightOcclusionTex.Load(pixelPos, 0).r;
					#else
						float occlusion = gLightOcclusionTex.Load(pixelPos, sampleIdx).r;
					#endif
				#else
				float occlusion = gLightOcclusionTex.Load(int3(pixelPos, 0)).r;
				#endif
				
				// Reverse the sqrt we did when storing it
				occlusion *= occlusion;
				
				occlusion = 1.0f - occlusion;
				
				bool isSpot = gShiftedLightPositionAndType.w > 0.5f;
				if(isSpot)
					return float4(getLuminanceSpot(lightData, worldPosition, V, R, roughness2, surfaceData) * occlusion, 1.0f);
				else // Radial
					return float4(getLuminanceRadial(lightData, worldPosition, V, R, roughness2, surfaceData) * occlusion, 1.0f);
			}
			else
				return float4(0.0f, 0.0f, 0.0f, 0.0f);
		}
	};
};