Compute Shader for Terrain Rendering

Texture2D texHeightMap : register( t0 ); RWTexture1D bufferResults : register( u0 );groupshared float groupResults[16 * 16];groupshared float4 stats;[numthreads(16, 16, 1)]void csMain( uint3 Gid : SV_GroupID, uint3 DTid : SV_DispatchThreadID, uint3 GTid : SV_GroupThreadID, uint GI : SV_GroupIndex ){   	// Gid  = The xyz index as spun up by the actual application call	//		  e.g. if ::Dispatch(16,16,1) is used then this will index into those bounds	// DTid = Similar to above, but the global offset, so for [numthreads(16,16,1)] and	//        ::Dispatch(16,16,1) this variable will range between 0-255,0-255,0	// GTid = The offset within the [numthreads()] bounds e.g. 0-15,0-15,0	// GI   = The flattened offset for this group e.g. 0-255 (16*16)		// Sample the appropriate 16x16 region	groupResults[GI] = texHeightMap.Load( uint3( DTid.xy, 0 ) ).r;		// Block until all threads have finished reading	GroupMemoryBarrierWithGroupSync();		// Then sum up the details	if(GI == 0)	{		// Thread #0 computes the minimum		// value from the raw data		float mn = 1e9f;				for(uint i = 0; i < 16 * 16; ++i)			if(groupResults < mn)				mn = groupResults;				// Store!		stats.r = mn;	}	else if(GI == 1)	{		// Thread #1 computes the maximum value		// from the raw data		float mx = -1e9f;				for(uint i = 0; i < 16 * 16; ++i)			if(groupResults > mx)				mx = groupResults;				// Store!		stats.g = mx;	}	else if(GI == 2)	{		// Thread #2 computes the average value		// from the raw data		float avg = 0.0f;				for(uint i = 0; i < 16 * 16; ++i)			avg += groupResults;					avg /= (16.0f * 16.0f);				// Store!		stats.b = avg;	}	else if(GI == 3)	{		// Thread #3 computes the standard		// deviation of the raw data		float avg = 0.0f;				for(uint i = 0; i < 16 * 16; ++i)			avg += groupResults;					avg /= (16.0f * 16.0f);				float stdDev = 0.0f;				for(uint i = 0; i < 16 * 16; ++i)			stdDev += pow(groupResults - avg, 2);				stdDev /= ((16.0f*16.0f)-1.0f);				stats.a = sqrt(stdDev);	}		GroupMemoryBarrierWithGroupSync();		if( GI == 0 )	{		// Determine which cell in the ouput to write		uint outIdx = Gid.x + Gid.y * 16;				// Store!		bufferResults[outIdx] = stats;	}}

LOG: Ran compute shader pre-pass, generated 256-element look-up table (4096 bytes) in 0.02ms. Used 16x16 groups of 16x16 threads over a 256x256 heightmap (65536 threads in total). [RunComputeShaderPrePass(...) @ line 1406]	Result 0 (for tile 0,0 starting at 0,0): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 1 (for tile 1,0 starting at 16,0): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 2 (for tile 2,0 starting at 32,0): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 3 (for tile 3,0 starting at 48,0): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 4 (for tile 4,0 starting at 64,0): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 5 (for tile 5,0 starting at 80,0): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 6 (for tile 6,0 starting at 96,0): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 7 (for tile 7,0 starting at 112,0): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 8 (for tile 8,0 starting at 128,0): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 9 (for tile 9,0 starting at 144,0): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 10 (for tile 10,0 starting at 160,0): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 11 (for tile 11,0 starting at 176,0): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 12 (for tile 12,0 starting at 192,0): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 13 (for tile 13,0 starting at 208,0): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 14 (for tile 14,0 starting at 224,0): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 15 (for tile 15,0 starting at 240,0): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 16 (for tile 0,1 starting at 0,16): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 17 (for tile 1,1 starting at 16,16): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 18 (for tile 2,1 starting at 32,16): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 19 (for tile 3,1 starting at 48,16): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 20 (for tile 4,1 starting at 64,16): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 21 (for tile 5,1 starting at 80,16): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 22 (for tile 6,1 starting at 96,16): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 23 (for tile 7,1 starting at 112,16): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 24 (for tile 8,1 starting at 128,16): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 25 (for tile 9,1 starting at 144,16): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 26 (for tile 10,1 starting at 160,16): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 27 (for tile 11,1 starting at 176,16): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 28 (for tile 12,1 starting at 192,16): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 29 (for tile 13,1 starting at 208,16): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 30 (for tile 14,1 starting at 224,16): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 31 (for tile 15,1 starting at 240,16): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 32 (for tile 0,2 starting at 0,32): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 33 (for tile 1,2 starting at 16,32): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 34 (for tile 2,2 starting at 32,32): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 35 (for tile 3,2 starting at 48,32): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 36 (for tile 4,2 starting at 64,32): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 37 (for tile 5,2 starting at 80,32): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 38 (for tile 6,2 starting at 96,32): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 39 (for tile 7,2 starting at 112,32): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 40 (for tile 8,2 starting at 128,32): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 41 (for tile 9,2 starting at 144,32): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 42 (for tile 10,2 starting at 160,32): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 43 (for tile 11,2 starting at 176,32): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 44 (for tile 12,2 starting at 192,32): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 45 (for tile 13,2 starting at 208,32): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 46 (for tile 14,2 starting at 224,32): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 47 (for tile 15,2 starting at 240,32): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 48 (for tile 0,3 starting at 0,48): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 49 (for tile 1,3 starting at 16,48): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 50 (for tile 2,3 starting at 32,48): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 51 (for tile 3,3 starting at 48,48): Minimum = 0.000, Maximum = 0.110, Average = 0.001, Standard Deviation = 0.008	Result 52 (for tile 4,3 starting at 64,48): Minimum = 0.000, Maximum = 0.333, Average = 0.027, Standard Deviation = 0.081	Result 53 (for tile 5,3 starting at 80,48): Minimum = 0.000, Maximum = 0.333, Average = 0.028, Standard Deviation = 0.083	Result 54 (for tile 6,3 starting at 96,48): Minimum = 0.000, Maximum = 0.333, Average = 0.021, Standard Deviation = 0.065	Result 55 (for tile 7,3 starting at 112,48): Minimum = 0.000, Maximum = 0.165, Average = 0.004, Standard Deviation = 0.020	Result 56 (for tile 8,3 starting at 128,48): Minimum = 0.000, Maximum = 0.161, Average = 0.006, Standard Deviation = 0.023	Result 57 (for tile 9,3 starting at 144,48): Minimum = 0.000, Maximum = 0.165, Average = 0.014, Standard Deviation = 0.041	Result 58 (for tile 10,3 starting at 160,48): Minimum = 0.000, Maximum = 0.196, Average = 0.015, Standard Deviation = 0.044	Result 59 (for tile 11,3 starting at 176,48): Minimum = 0.000, Maximum = 0.157, Average = 0.008, Standard Deviation = 0.025	Result 60 (for tile 12,3 starting at 192,48): Minimum = 0.000, Maximum = 0.027, Average = 0.000, Standard Deviation = 0.002	Result 61 (for tile 13,3 starting at 208,48): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 62 (for tile 14,3 starting at 224,48): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 63 (for tile 15,3 starting at 240,48): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 64 (for tile 0,4 starting at 0,64): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 65 (for tile 1,4 starting at 16,64): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 66 (for tile 2,4 starting at 32,64): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 67 (for tile 3,4 starting at 48,64): Minimum = 0.000, Maximum = 0.333, Average = 0.027, Standard Deviation = 0.081	Result 68 (for tile 4,4 starting at 64,64): Minimum = 0.443, Maximum = 1.000, Average = 0.945, Standard Deviation = 0.115	Result 69 (for tile 5,4 starting at 80,64): Minimum = 0.667, Maximum = 1.000, Average = 0.971, Standard Deviation = 0.083	Result 70 (for tile 6,4 starting at 96,64): Minimum = 0.302, Maximum = 1.000, Average = 0.788, Standard Deviation = 0.196	Result 71 (for tile 7,4 starting at 112,64): Minimum = 0.000, Maximum = 0.780, Average = 0.426, Standard Deviation = 0.218	Result 72 (for tile 8,4 starting at 128,64): Minimum = 0.000, Maximum = 0.498, Average = 0.191, Standard Deviation = 0.136	Result 73 (for tile 9,4 starting at 144,64): Minimum = 0.310, Maximum = 0.733, Average = 0.503, Standard Deviation = 0.090	Result 74 (for tile 10,4 starting at 160,64): Minimum = 0.333, Maximum = 0.737, Average = 0.651, Standard Deviation = 0.113	Result 75 (for tile 11,4 starting at 176,64): Minimum = 0.047, Maximum = 0.737, Average = 0.413, Standard Deviation = 0.224	Result 76 (for tile 12,4 starting at 192,64): Minimum = 0.000, Maximum = 0.082, Average = 0.006, Standard Deviation = 0.018	Result 77 (for tile 13,4 starting at 208,64): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 78 (for tile 14,4 starting at 224,64): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 79 (for tile 15,4 starting at 240,64): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 80 (for tile 0,5 starting at 0,80): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 81 (for tile 1,5 starting at 16,80): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 82 (for tile 2,5 starting at 32,80): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 83 (for tile 3,5 starting at 48,80): Minimum = 0.000, Maximum = 0.333, Average = 0.028, Standard Deviation = 0.083	Result 84 (for tile 4,5 starting at 64,80): Minimum = 0.533, Maximum = 1.000, Average = 0.927, Standard Deviation = 0.116	Result 85 (for tile 5,5 starting at 80,80): Minimum = 0.502, Maximum = 0.996, Average = 0.779, Standard Deviation = 0.151	Result 86 (for tile 6,5 starting at 96,80): Minimum = 0.000, Maximum = 0.925, Average = 0.488, Standard Deviation = 0.305	Result 87 (for tile 7,5 starting at 112,80): Minimum = 0.000, Maximum = 0.380, Average = 0.157, Standard Deviation = 0.091	Result 88 (for tile 8,5 starting at 128,80): Minimum = 0.055, Maximum = 0.733, Average = 0.402, Standard Deviation = 0.185	Result 89 (for tile 9,5 starting at 144,80): Minimum = 0.263, Maximum = 0.737, Average = 0.638, Standard Deviation = 0.116	Result 90 (for tile 10,5 starting at 160,80): Minimum = 0.251, Maximum = 0.737, Average = 0.611, Standard Deviation = 0.177	Result 91 (for tile 11,5 starting at 176,80): Minimum = 0.000, Maximum = 0.737, Average = 0.313, Standard Deviation = 0.304	Result 92 (for tile 12,5 starting at 192,80): Minimum = 0.000, Maximum = 0.008, Average = 0.000, Standard Deviation = 0.000	Result 93 (for tile 13,5 starting at 208,80): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 94 (for tile 14,5 starting at 224,80): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 95 (for tile 15,5 starting at 240,80): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 96 (for tile 0,6 starting at 0,96): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 97 (for tile 1,6 starting at 16,96): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 98 (for tile 2,6 starting at 32,96): Minimum = 0.000, Maximum = 0.000, Average = 0.000, Standard Deviation = 0.000	Result 99 (for tile 3,6 starting at 48,96): Minimum = 0.000, Maximum = 0.333, Average = 0.027, Standard Deviation = 0.080	Result 100 (for tile 4,6 starting at 64,96): Minimum = 0.498, Maximum = 1.000, Average = 0.693, Standard Deviation = 0.184	Result 101 (for tile 5,6 starting at 80,96): Minimum = 0.000, Maximum = 0.686