Rectilinear grid support

NvdbRectilinear has not been really tested.

Author: tarcila

devices/rtx/README.md

@@ -99,6 +99,40 @@ box; omitting either leaves the bound open.
 **Parameters:**
 - `roi` (`FLOAT32_BOX3`): the restriction box to apply (default: unbounded).
 
+
+#### VISRTX_SPATIAL_FIELD_STRUCTURED_RECTILINEAR
+
+The `structuredRectilinear` spatial field type provides efficient sampling of structured grids with 
+rectilinear (non-uniform) spacing. Unlike `structuredRegular` which assumes uniform spacing, this type 
+requires explicit 1D coordinate arrays for each axis.
+
+**Parameters:**
+- `data` (ARRAY3D): The 3D voxel data
+- `coordsX` (ARRAY1D): X-axis coordinates (required)
+- `coordsY` (ARRAY1D): Y-axis coordinates (required)
+- `coordsZ` (ARRAY1D): Z-axis coordinates (required)
+- `filter`: Filtering method (same as structuredRegular)
+- `dataCentering`: Cell vs node centering (same as structuredRegular)
+
+The axis coordinate arrays define the actual position of each voxel along that axis, enabling 
+support for non-uniform grid spacing commonly found in scientific simulations.
+
+#### VISRTX_SPATIAL_FIELD_NANOVDB_RECTILINEAR
+
+The `nanovdbRectilinear` spatial field type extends NanoVDB support to rectilinear grids. 
+It supports all NanoVDB grid types (Fp4, Fp8, Fp16, FpN, Float) with rectilinear coordinate transforms.
+
+**Parameters:**
+- `gridData` (ARRAY1D): Serialized NanoVDB grid data
+- `coordsX` (ARRAY1D): X-axis coordinates (required)
+- `coordsY` (ARRAY1D): Y-axis coordinates (required)
+- `coordsZ` (ARRAY1D): Z-axis coordinates (required)
+- `filter`: Filtering method
+- `dataCentering`: Cell vs node centering
+
+This type automatically detects the grid type from the NanoVDB metadata and routes to the 
+appropriate sampler implementation.
+
 ## Additional ANARI Parameter and Property Extensions
 
 The following section describes what additional parameters and properties can be
@@ -178,6 +212,8 @@ The following extensions are either partially or fully implemented by VisRTX:
 - `VISRTX_TRIANGLE_BACK_FACE_CULLING`
 - `VISRTX_SPATIAL_FIELD_DATA_CENTERING`
 - `VISRTX_SPATIAL_FIELD_REGION_OF_INTEREST`
+- `VISRTX_SPATIAL_FIELD_STRUCTURED_RECTILINEAR`
+- `VISRTX_SPATIAL_FIELD_NANOVDB_RECTILINEAR`
 
 For any found bugs in extensions that are implemented, please [open an
 issue](https://github.com/NVIDIA/VisRTX/issues/new)!

devices/rtx/device/CMakeLists.txt

@@ -1,4 +1,4 @@
-# Copyright (c) 2019-2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# Copyright (c) 2019-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 # SPDX-License-Identifier: BSD-3-Clause
 #
 # Redistribution and use in source and binary forms, with or without
@@ -180,10 +180,14 @@ set(SOURCES
   sampler/UnknownSampler.cpp
 
   spatial_field/SpatialField.cpp
+  spatial_field/NvdbRectilinearField.cpp
   spatial_field/NvdbRegularField.cpp
+  spatial_field/StructuredRectilinearField.cpp
   spatial_field/StructuredRegularField.cpp
   spatial_field/UnknownSpatialField.cpp
+  spatial_field/NvdbRectilinearSampler.cpp
   spatial_field/NvdbRegularSampler.cpp
+  spatial_field/StructuredRectilinearSampler.cpp
   spatial_field/StructuredRegularSampler.cpp
   spatial_field/space_skipping/UniformGrid.cu
 
@@ -363,7 +367,9 @@ GenerateEmbeddedPTX(geometry Intersectors)
 GenerateEmbeddedPTX(material/shaders MatteShader ENTRIES __direct__callable__evalSurfaceMaterial)
 GenerateEmbeddedPTX(material/shaders PhysicallyBasedShader ENTRIES __direct__callable__evalSurfaceMaterial)
 GenerateEmbeddedPTX(spatial_field NvdbRegularSampler)
+GenerateEmbeddedPTX(spatial_field NvdbRectilinearSampler)
 GenerateEmbeddedPTX(spatial_field StructuredRegularSampler)
+GenerateEmbeddedPTX(spatial_field StructuredRectilinearSampler)
 if(VISRTX_ENABLE_MDL_SUPPORT)
   GenerateEmbeddedPTX(material/shaders MDLShader ENTRIES __direct__callable__evalSurfaceMaterial)
   GenerateEmbeddedPTX(material/shaders MDLTexture)

devices/rtx/device/VisRTXDevice.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+ * Copyright (c) 2019-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
  * SPDX-License-Identifier: BSD-3-Clause
  *
  * Redistribution and use in source and binary forms, with or without
@@ -67,8 +67,10 @@
 #include "material/shaders/PhysicallyBasedShader.h"
 
 // spatial field samplers
-#include "spatial_field/StructuredRegularSampler.h"
+#include "spatial_field/NvdbRectilinearSampler.h"
 #include "spatial_field/NvdbRegularSampler.h"
+#include "spatial_field/StructuredRectilinearSampler.h"
+#include "spatial_field/StructuredRegularSampler.h"
 
 // MDL
 #ifdef USE_MDL
@@ -786,6 +788,12 @@ DeviceInitStatus VisRTXDevice::initOptix()
       init_module(&state.fieldSamplers.nvdb,
           NvdbRegularSampler::ptx(),
           "'nvdb' field sampler"),
+      init_module(&state.fieldSamplers.structuredRectilinear,
+          StructuredRectilinearSampler::ptx(),
+          "'structuredRectilinear' field sampler"),
+      init_module(&state.fieldSamplers.nvdbRectilinear,
+          NvdbRectilinearSampler::ptx(),
+          "'nanovdbRectilinear' field sampler"),
   };
 
   for (auto &f : compileTasks)

devices/rtx/device/gpu/gpu_objects.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+ * Copyright (c) 2019-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
  * SPDX-License-Identifier: BSD-3-Clause
  *
  * Redistribution and use in source and binary forms, with or without
@@ -425,13 +425,37 @@ struct NVdbRegularData
   NVdbRegularData() = default;
 };
 
+struct StructuredRectilinearData
+{
+  cudaTextureObject_t texObj;
+  vec3 dims;
+  bool cellCentered;
+  cudaTextureObject_t axisLUT[3];
+  vec3 axisBoundsMin;
+  vec3 axisBoundsMax;
+
+  StructuredRectilinearData() = default;
+};
+
+struct NVdbRectilinearData
+{
+  nanovdb::GridType gridType;
+  const void *gridData;
+  bool cellCentered;
+  cudaTextureObject_t axisLUT[3];
+
+  NVdbRectilinearData() = default;
+};
+
 struct SpatialFieldGPUData
 {
   SbtCallableEntryPoints samplerCallableIndex{SbtCallableEntryPoints::Invalid};
   union
   {
     StructuredRegularData structuredRegular;
     NVdbRegularData nvdbRegular;
+    StructuredRectilinearData structuredRectilinear;
+    NVdbRectilinearData nvdbRectilinear;
   } data;
   UniformGridData grid;
   box3 roi;
@@ -507,9 +531,10 @@ struct RectLightGPUData
   vec3 edge1;
   vec3 edge2;
   float intensity;
-  struct {
-    unsigned int front: 1;
-    unsigned int back: 1;
+  struct
+  {
+    unsigned int front : 1;
+    unsigned int back : 1;
   } side;
   float oneOverArea;
 };

devices/rtx/device/gpu/sbt.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+ * Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
  * SPDX-License-Identifier: BSD-3-Clause
  *
  * Redistribution and use in source and binary forms, with or without
@@ -61,12 +61,31 @@ enum class SbtCallableEntryPoints : uint32_t
   Matte = 0,
   PBR = Matte + int(SurfaceShaderEntryPoints::Count),
   SpatialFieldSamplerRegular = PBR + int(SurfaceShaderEntryPoints::Count),
-  SpatialFieldSamplerNvdbFp4 = SpatialFieldSamplerRegular + int(SpatialFieldSamplerEntryPoints::Count),
-  SpatialFieldSamplerNvdbFp8 = SpatialFieldSamplerNvdbFp4 + int(SpatialFieldSamplerEntryPoints::Count),
-  SpatialFieldSamplerNvdbFp16 = SpatialFieldSamplerNvdbFp8 + int(SpatialFieldSamplerEntryPoints::Count),
-  SpatialFieldSamplerNvdbFpN = SpatialFieldSamplerNvdbFp16 + int(SpatialFieldSamplerEntryPoints::Count),
-  SpatialFieldSamplerNvdbFloat = SpatialFieldSamplerNvdbFpN + int(SpatialFieldSamplerEntryPoints::Count),
-  Last = SpatialFieldSamplerNvdbFloat + int(SpatialFieldSamplerEntryPoints::Count),
+  SpatialFieldSamplerNvdbFp4 =
+      SpatialFieldSamplerRegular + int(SpatialFieldSamplerEntryPoints::Count),
+  SpatialFieldSamplerNvdbFp8 =
+      SpatialFieldSamplerNvdbFp4 + int(SpatialFieldSamplerEntryPoints::Count),
+  SpatialFieldSamplerNvdbFp16 =
+      SpatialFieldSamplerNvdbFp8 + int(SpatialFieldSamplerEntryPoints::Count),
+  SpatialFieldSamplerNvdbFpN =
+      SpatialFieldSamplerNvdbFp16 + int(SpatialFieldSamplerEntryPoints::Count),
+  SpatialFieldSamplerNvdbFloat =
+      SpatialFieldSamplerNvdbFpN + int(SpatialFieldSamplerEntryPoints::Count),
+  SpatialFieldSamplerRectilinear =
+      SpatialFieldSamplerNvdbFloat + int(SpatialFieldSamplerEntryPoints::Count),
+  SpatialFieldSamplerNvdbRectilinearFp4 = SpatialFieldSamplerRectilinear
+      + int(SpatialFieldSamplerEntryPoints::Count),
+  SpatialFieldSamplerNvdbRectilinearFp8 = SpatialFieldSamplerNvdbRectilinearFp4
+      + int(SpatialFieldSamplerEntryPoints::Count),
+  SpatialFieldSamplerNvdbRectilinearFp16 = SpatialFieldSamplerNvdbRectilinearFp8
+      + int(SpatialFieldSamplerEntryPoints::Count),
+  SpatialFieldSamplerNvdbRectilinearFpN = SpatialFieldSamplerNvdbRectilinearFp16
+      + int(SpatialFieldSamplerEntryPoints::Count),
+  SpatialFieldSamplerNvdbRectilinearFloat =
+      SpatialFieldSamplerNvdbRectilinearFpN
+      + int(SpatialFieldSamplerEntryPoints::Count),
+  Last = SpatialFieldSamplerNvdbRectilinearFloat
+      + int(SpatialFieldSamplerEntryPoints::Count),
 };
 
 } // namespace visrtx

devices/rtx/device/gpu/shadingState.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+ * Copyright (c) 2019-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
  * SPDX-License-Identifier: BSD-3-Clause
  *
  * Redistribution and use in source and binary forms, with or without
@@ -91,9 +91,9 @@ struct TextureHandler : mi::neuraylib::Texture_handler_base
 using ShadingStateMaterial = mi::neuraylib::Shading_state_material;
 using ResourceData = mi::neuraylib::Resource_data;
 
-struct alignas(8)  MDLShadingState
+struct alignas(8) MDLShadingState
 {
-  const char * argBlock;
+  const char *argBlock;
 
   ShadingStateMaterial state;
   TextureHandler textureHandler;
@@ -139,6 +139,17 @@ struct StructuredRegularSamplerState
   vec3 offset;
 };
 
+// Structured Rectilinear Sampler State
+struct StructuredRectilinearSamplerState
+{
+  cudaTextureObject_t texObj;
+  vec3 dims;
+  vec3 offset;
+  cudaTextureObject_t axisLUT[3];
+  vec3 axisBoundsMin;
+  vec3 axisBoundsMax;
+};
+
 // NanoVDB Sampler States
 template <typename T>
 struct NvdbRegularSamplerState
@@ -156,6 +167,24 @@ struct NvdbRegularSamplerState
   nanovdb::Vec3f indexMax;
 };
 
+// NanoVDB Rectilinear Sampler States
+template <typename T>
+struct NvdbRectilinearSamplerState
+{
+  using GridType = nanovdb::Grid<nanovdb::NanoTree<T>>;
+  using AccessorType = typename GridType::AccessorType;
+  using SamplerType = nanovdb::math::SampleFromVoxels<AccessorType, 1>;
+
+  const GridType *grid;
+  AccessorType accessor;
+  SamplerType sampler;
+  nanovdb::Vec3f offset;
+  nanovdb::Vec3f scale;
+  nanovdb::Vec3f indexMin;
+  nanovdb::Vec3f indexMax;
+  cudaTextureObject_t axisLUT[3];
+};
+
 struct VolumeSamplingState
 {
   VISRTX_DEVICE VolumeSamplingState() {};
@@ -168,6 +197,12 @@ struct VolumeSamplingState
     NvdbRegularSamplerState<nanovdb::Fp16> nvdbFp16;
     NvdbRegularSamplerState<nanovdb::FpN> nvdbFpN;
     NvdbRegularSamplerState<float> nvdbFloat;
+    StructuredRectilinearSamplerState structuredRectilinear;
+    NvdbRectilinearSamplerState<nanovdb::Fp4> nvdbRectilinearFp4;
+    NvdbRectilinearSamplerState<nanovdb::Fp8> nvdbRectilinearFp8;
+    NvdbRectilinearSamplerState<nanovdb::Fp16> nvdbRectilinearFp16;
+    NvdbRectilinearSamplerState<nanovdb::FpN> nvdbRectilinearFpN;
+    NvdbRectilinearSamplerState<float> nvdbRectilinearFloat;
   };
 };
 

devices/rtx/device/include/anari/ext/visrtx/visrtx_extensions.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+ * Copyright (c) 2019-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
  * SPDX-License-Identifier: BSD-3-Clause
  *
  * Redistribution and use in source and binary forms, with or without
@@ -48,6 +48,8 @@ struct VisRTXExtensions
   int VISRTX_SPATIAL_FIELD_NANOVDB;
   int VISRTX_SPATIAL_FIELD_DATA_CENTERING;
   int VISRTX_SPATIAL_FIELD_REGION_OF_INTEREST;
+  int VISRTX_SPATIAL_FIELD_STRUCTURED_RECTILINEAR;
+  int VISRTX_SPATIAL_FIELD_NANOVDB_RECTILINEAR;
   int VISRTX_TRIANGLE_BACK_FACE_CULLING;
   int VISRTX_TRIANGLE_FACE_VARYING_ATTRIBUTES;
 };
@@ -114,6 +116,10 @@ inline void fillExtensionStruct(
       extensions->VISRTX_SPATIAL_FIELD_REGION_OF_INTEREST = 1;
     else if (feature == "ANARI_VISRTX_SPATIAL_FIELD_NANOVDB")
       extensions->VISRTX_SPATIAL_FIELD_NANOVDB = 1;
+    else if (feature == "ANARI_VISRTX_SPATIAL_FIELD_STRUCTURED_RECTILINEAR")
+      extensions->VISRTX_SPATIAL_FIELD_STRUCTURED_RECTILINEAR = 1;
+    else if (feature == "ANARI_VISRTX_SPATIAL_FIELD_NANOVDB_RECTILINEAR")
+      extensions->VISRTX_SPATIAL_FIELD_NANOVDB_RECTILINEAR = 1;
     else if (feature == "ANARI_VISRTX_TRIANGLE_BACK_FACE_CULLING")
       extensions->VISRTX_TRIANGLE_BACK_FACE_CULLING = 1;
     else if (feature == "ANARI_VISRTX_TRIANGLE_FACE_VARYING_ATTRIBUTES")

devices/rtx/device/optix_visrtx.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+ * Copyright (c) 2019-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
  * SPDX-License-Identifier: BSD-3-Clause
  *
  * Redistribution and use in source and binary forms, with or without
@@ -199,6 +199,8 @@ struct DeviceGlobalState : public helium::BaseGlobalDeviceState
   {
     OptixModule structuredRegular{nullptr};
     OptixModule nvdb{nullptr};
+    OptixModule structuredRectilinear{nullptr};
+    OptixModule nvdbRectilinear{nullptr};
   } fieldSamplers;
 
   struct ObjectUpdates