Lightlistbuild optimizations

Calculate linear depths as part of depth min/max calculation to avoid
fetching depth twice.
Store camera dimensions in uniforms instead of using GetDimensions

Assets/ScriptableRenderLoop/fptl/FptlLighting.cs

             cmd.SetComputeBufferParam(m_BuildScreenAABBShader, kGenAABBKernel, "g_vBoundsBuffer", m_aabbBoundsBuffer);
             cmd.ComputeDispatch(m_BuildScreenAABBShader, kGenAABBKernel, (numLights + 7) / 8, 1, 1);
 
+            cmd.SetComputeIntParams(m_BuildPerTileLightListShader, "g_viDimensions", new int[2] { iW, iH });
             cmd.SetComputeIntParam(m_BuildPerTileLightListShader, "g_iNrVisibLights", numLights);
             SetMatrixCS(cmd, m_BuildPerTileLightListShader, "g_mScrProjection", projscr);
             SetMatrixCS(cmd, m_BuildPerTileLightListShader, "g_mInvScrProjection", invProjscr);

Assets/ScriptableRenderLoop/fptl/lightlistbuild.compute

 
 
 uniform int g_iNrVisibLights;
+uniform uint2 g_viDimensions;
 uniform float4x4 g_mInvScrProjection;
 uniform float4x4 g_mScrProjection;
 
 	if(t<MAX_NR_COARSE_ENTRIES)
 		prunedList[t]=0;
 	
-	uint iWidth;
-	uint iHeight;
-	g_depth_tex.GetDimensions(iWidth, iHeight);
+	uint iWidth = g_viDimensions.x;
+	uint iHeight = g_viDimensions.y;
 	uint nrTilesX = (iWidth+15)/16;
 	uint nrTilesY = (iHeight+15)/16;
 
 	// establish min and max depth first
 	float dpt_mi=asfloat(uFltMax), dpt_ma=0.0;
 
-	for(int idx=t; idx<256; idx+=NR_THREADS)
+
+	float4 vLinDepths;
-		uint2 uCrd = min( uint2(viTilLL.x+(idx&0xf), viTilLL.y+(idx>>4)), uint2(iWidth-1, iHeight-1) );
-		const float fDpth = FetchDepth(g_depth_tex, uCrd);
-		if(fDpth<VIEWPORT_SCALE_Z)		// if not skydome
+		// Fetch depths and calculate min/max
+		[unroll]
+		for(int i = 0; i < 4; i++)
-			dpt_mi = min(fDpth, dpt_mi);
-			dpt_ma = max(fDpth, dpt_ma);
+			int idx = i * NR_THREADS + t;
+			uint2 uCrd = min( uint2(viTilLL.x+(idx&0xf), viTilLL.y+(idx>>4)), uint2(iWidth-1, iHeight-1) );
+			const float fDepth = FetchDepth(g_depth_tex, uCrd);
+			vLinDepths[i] = GetLinearDepth(fDepth);
+			if(fDepth<VIEWPORT_SCALE_Z)		// if not skydome
+			{
+				dpt_mi = min(fDepth, dpt_mi);
+				dpt_ma = max(fDepth, dpt_ma);
+			}
-	}
-	InterlockedMax(ldsZMax, asuint(dpt_ma) );
-	InterlockedMin(ldsZMin, asuint(dpt_mi) );
+		InterlockedMax(ldsZMax, asuint(dpt_ma));
+		InterlockedMin(ldsZMin, asuint(dpt_mi));
-	GroupMemoryBarrierWithGroupSync();
+		GroupMemoryBarrierWithGroupSync();
+	}
 
 
 	float3 vTileLL = float3(viTilLL.x/(float) iWidth, viTilLL.y/(float) iHeight, asfloat(ldsZMin));
 	}
 #else
 	{
-		float4 vLinDepths;
-		[unroll]for(int i=0; i<4; i++)
-		{
-			int idx = t + i*NR_THREADS;
-			uint2 uCrd = min( uint2(viTilLL.x+(idx&0xf), viTilLL.y+(idx>>4)), uint2(iWidth-1, iHeight-1) );
-			float3 v3ScrPos = float3(uCrd.x+0.5, uCrd.y+0.5, FetchDepth(g_depth_tex, uCrd));
-			vLinDepths[i] = GetLinearDepth(v3ScrPos.z);
-		}
-
 		uint uLightsFlags[2] = {0,0};
 		int l=0;
 		// need this outer loop even on xb1 and ps4 since direct lights and