130 lines
3.2 KiB
Python
130 lines
3.2 KiB
Python
/*
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* Copyright 2018 Kostas Anagnostou. All rights reserved.
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* License: https://github.com/bkaradzic/bgfx/blob/master/LICENSE
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*/
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#include "bgfx_compute.sh"
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//the per drawcall data that is constant (noof indices and offsets to vertex/index buffers)
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BUFFER_RO(drawcallConstData, uint, 0);
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//instance data for all instances (pre culling)
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BUFFER_RO(instanceDataIn, vec4, 1);
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//per instance visibility (output of culling pass)
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BUFFER_RO(instancePredicates, bool, 2);
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//how many instances per drawcall
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BUFFER_RW(drawcallInstanceCount, uint, 3);
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//drawcall data that will drive drawIndirect
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BUFFER_RW(drawcallData, uvec4, 4);
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//culled instance data
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BUFFER_WR(instanceDataOut, vec4, 5);
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uniform vec4 u_cullingConfig;
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// Based on Parallel Prefix Sum (Scan) with CUDA by Mark Harris
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SHARED uint temp[2048];
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NUM_THREADS(1024, 1, 1)
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void main()
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{
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uint tID = gl_GlobalInvocationID.x;
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int NoofInstancesPowOf2 = int(u_cullingConfig.y);
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int NoofDrawcalls = int(u_cullingConfig.w);
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int offset = 1;
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bool predicate = instancePredicates[2 * tID];
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temp[2 * tID] = uint(predicate ? 1 : 0);
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predicate = instancePredicates[2 * tID + 1];
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temp[2 * tID + 1] = uint(predicate ? 1 : 0);
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int d;
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//perform reduction
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for (d = NoofInstancesPowOf2 >> 1; d > 0; d >>= 1)
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{
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barrier();
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if (tID < d)
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{
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int ai = int(offset * (2 * tID + 1) - 1);
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int bi = int(offset * (2 * tID + 2) - 1);
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temp[bi] += temp[ai];
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}
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offset *= 2;
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}
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// clear the last element
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if (tID == 0)
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{
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temp[NoofInstancesPowOf2 - 1] = 0;
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}
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// perform downsweep and build scan
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for ( d = 1; d < NoofInstancesPowOf2; d *= 2)
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{
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offset >>= 1;
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barrier();
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if (tID < d)
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{
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int ai = int(offset * (2 * tID + 1) - 1);
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int bi = int(offset * (2 * tID + 2) - 1);
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int t = int(temp[ai]);
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temp[ai] = temp[bi];
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temp[bi] += t;
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}
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}
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barrier();
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int index = int(2 * tID);
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// scatter results
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predicate = instancePredicates[index];
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if (predicate)
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{
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instanceDataOut[4 * temp[index] ] = instanceDataIn[4 * index ];
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instanceDataOut[4 * temp[index] + 1] = instanceDataIn[4 * index + 1];
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instanceDataOut[4 * temp[index] + 2] = instanceDataIn[4 * index + 2];
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instanceDataOut[4 * temp[index] + 3] = instanceDataIn[4 * index + 3];
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}
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index = int(2 * tID + 1);
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predicate = instancePredicates[index];
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if (predicate)
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{
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instanceDataOut[4 * temp[index] ] = instanceDataIn[4 * index ];
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instanceDataOut[4 * temp[index] + 1] = instanceDataIn[4 * index + 1];
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instanceDataOut[4 * temp[index] + 2] = instanceDataIn[4 * index + 2];
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instanceDataOut[4 * temp[index] + 3] = instanceDataIn[4 * index + 3];
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}
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if (tID == 0)
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{
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uint startInstance = 0;
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//copy data to indirect buffer, could possible be done in a different compute shader
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for (int k = 0; k < NoofDrawcalls; k++)
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{
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drawIndexedIndirect(
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drawcallData,
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k,
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drawcallConstData[ k * 3 ], //number of indices
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drawcallInstanceCount[k], //number of instances
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drawcallConstData[ k * 3 + 1 ], //offset into the index buffer
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drawcallConstData[ k * 3 + 2 ], //offset into the vertex buffer
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startInstance //offset into the instance buffer
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);
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startInstance += drawcallInstanceCount[k];
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drawcallInstanceCount[k] = 0;
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}
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}
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}
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