Implement sub-sampling in raytracing code (#277)

* Implement sub-sampling in raytracing code

* Review fixes

Author: prybicki

include/rgl/api/core.h

@@ -382,6 +382,15 @@ typedef enum : int32_t
 	RGL_FIELD_DYNAMIC_FORMAT = 13842,
 } rgl_field_t;
 
+/**
+ * Kinds of return type for multi-return LiDAR output.
+ */
+typedef enum : int32_t
+{
+	RGL_RETURN_TYPE_FIRST = 0,
+	RGL_RETURN_TYPE_LAST = 1,
+} rgl_return_type_t;
+
 /**
  * Helper enum for axis selection
  */

src/gpu/MultiReturn.hpp

@@ -0,0 +1,28 @@
+// Copyright 2024 Robotec.AI
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include <RGLFields.hpp>
+
+#define MULTI_RETURN_BEAM_VERTICES 8
+#define MULTI_RETURN_BEAM_CIRCLES 2
+#define MULTI_RETURN_BEAM_SAMPLES (1 + (MULTI_RETURN_BEAM_VERTICES * MULTI_RETURN_BEAM_CIRCLES))
+
+struct MultiReturnPointers
+{
+	Field<IS_HIT_I32>::type* isHit;
+	Field<XYZ_VEC3_F32>::type* xyz;
+	Field<DISTANCE_F32>::type* distance;
+};

src/gpu/RaytraceRequestContext.hpp

@@ -16,6 +16,7 @@
 
 #include <optix.h>
 #include <RGLFields.hpp>
+#include <gpu/MultiReturn.hpp>
 
 struct RaytraceRequestContext
 {
@@ -38,7 +39,7 @@ struct RaytraceRequestContext
 	const int* ringIds;
 	size_t ringIdsCount;
 
-	const float* rayTimeOffsets;
+	const float* rayTimeOffsetsMs;
 	size_t rayTimeOffsetsCount;
 
 	OptixTraversableHandle scene;
@@ -61,5 +62,9 @@ struct RaytraceRequestContext
 	Field<ELEVATION_F32>::type* elevation;
 	Field<NORMAL_VEC3_F32>::type* normal;
 	Field<INCIDENT_ANGLE_F32>::type* incidentAngle;
+
+	// Multi-Return
+	float beamHalfDivergence;
+	MultiReturnPointers mrSamples;
 };
 static_assert(std::is_trivially_copyable<RaytraceRequestContext>::value);