Implement sub-sampling reduction kernels

src/gpu/nodeKernels.cu

@@ -223,6 +223,34 @@ __global__ void kFilterGroundPoints(size_t pointCount, const Vec3f sensor_up_vec
 	outNonGround[tid] = normalUpAngle > ground_angle_threshold;
 }
 
+__global__ void kProcessBeamSamplesFirstLast(size_t beamCount, int samplesPerBeam, MultiReturnPointers beamSamples,
+                                             MultiReturnPointers first, MultiReturnPointers last)
+{
+	LIMIT(beamCount);
+
+	const auto beamIdx = tid;
+	int firstIdx = 0;
+	int lastIdx = 0;
+	for (int sampleIdx = 0; sampleIdx < samplesPerBeam; ++sampleIdx) {
+		if (beamSamples.isHit[beamIdx * samplesPerBeam + sampleIdx] == 0) {
+			continue;
+		}
+		if (beamSamples.distance[beamIdx * samplesPerBeam + sampleIdx] <
+		    beamSamples.distance[beamIdx * samplesPerBeam + firstIdx]) {
+			firstIdx = sampleIdx;
+		}
+		if (beamSamples.distance[beamIdx * samplesPerBeam + sampleIdx] >
+		    beamSamples.distance[beamIdx * samplesPerBeam + lastIdx]) {
+			lastIdx = sampleIdx;
+		}
+	}
+	first.xyz[beamIdx] = beamSamples.xyz[beamIdx * samplesPerBeam + firstIdx];
+	first.distance[beamIdx] = beamSamples.distance[beamIdx * samplesPerBeam + firstIdx];
+	last.xyz[beamIdx] = beamSamples.xyz[beamIdx * samplesPerBeam + lastIdx];
+	last.distance[beamIdx] = beamSamples.distance[beamIdx * samplesPerBeam + lastIdx];
+}
+
+
 void gpuFindCompaction(cudaStream_t stream, size_t pointCount, const int32_t* shouldCompact,
                        CompactionIndexType* hitCountInclusive, size_t* outHitCount)
 {
@@ -294,3 +322,9 @@ void gpuRadarComputeEnergy(cudaStream_t stream, size_t count, float rayAzimuthSt
 	run(kRadarComputeEnergy, stream, count, rayAzimuthStepRad, rayElevationStepRad, freq, lookAtOriginTransform, rayPose,
 	    hitDist, hitNorm, hitPos, outBUBRFactor);
 }
+
+void gpuProcessBeamSamplesFirstLast(cudaStream_t stream, size_t beamCount, int samplesPerBeam, MultiReturnPointers beamSamples,
+                                    MultiReturnPointers first, MultiReturnPointers last)
+{
+	run(kProcessBeamSamplesFirstLast, stream, beamCount, samplesPerBeam, beamSamples, first, last);
+}

src/gpu/nodeKernels.hpp

@@ -22,6 +22,7 @@
 #include <math/Mat3x4f.hpp>
 #include <RGLFields.hpp>
 #include <thrust/complex.h>
+#include <gpu/MultiReturn.hpp>
 
 /*
  * The following functions are asynchronous!
@@ -50,4 +51,6 @@ void gpuFilterGroundPoints(cudaStream_t stream, size_t pointCount, const Vec3f s
 void gpuRadarComputeEnergy(cudaStream_t stream, size_t count, float rayAzimuthStepRad, float rayElevationStepRad, float freq,
                            Mat3x4f lookAtOriginTransform, const Field<RAY_POSE_MAT3x4_F32>::type* rayPose,
                            const Field<DISTANCE_F32>::type* hitDist, const Field<NORMAL_VEC3_F32>::type* hitNorm,
-                           const Field<XYZ_VEC3_F32>::type* hitPos, Vector<3, thrust::complex<float>>* outBUBRFactor);
+                           const Field<XYZ_VEC3_F32>::type* hitPos, Vector<3, thrust::complex<float>>* outBUBRFactor);
+void gpuProcessBeamSamplesFirstLast(cudaStream_t stream, size_t beamCount, int samplesPerBeam, MultiReturnPointers beamSamples,
+                                    MultiReturnPointers first, MultiReturnPointers last);

src/graph/RaytraceNode.cpp

@@ -132,6 +132,9 @@ void RaytraceNode::enqueueExecImpl()
 	std::size_t pipelineArgsSize = requestCtxDev->getSizeOf() * requestCtxDev->getCount();
 	CHECK_OPTIX(optixLaunch(Optix::getOrCreate().pipeline, getStreamHandle(), pipelineArgsPtr, pipelineArgsSize, &sceneSBT,
 	                        launchDims.x, launchDims.y, launchDims.y));
+
+	gpuProcessBeamSamplesFirstLast(getStreamHandle(), raysNode->getRayCount(), MULTI_RETURN_BEAM_SAMPLES,
+	                               mrSamples.getPointers(), mrFirst.getPointers(), mrLast.getPointers());
 }
 
 void RaytraceNode::setFields(const std::set<rgl_field_t>& fields)