Cycles: Add NanoVDB support for rendering volumes

NanoVDB is a platform-independent sparse volume data structure that makes it possible to
use OpenVDB volumes on the GPU. This patch uses it for volume rendering in Cycles,
replacing the previous usage of dense 3D textures.

Since it has a big impact on memory usage and performance and changes the OpenVDB
branch used for the rest of Blender as well, this is not enabled by default yet, which will
happen only after 2.82 was branched off. To enable it, build both dependencies and Blender
itself with the "WITH_NANOVDB" CMake option.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D8794

1 files changed, 48 insertions, 37 deletions

diff --git a/intern/cycles/device/cuda/device_cuda_impl.cpp b/intern/cycles/device/cuda/device_cuda_impl.cpp
index 3a2eb8df95b..01adf10f252 100644
--- a/intern/cycles/device/cuda/device_cuda_impl.cpp
+++ b/intern/cycles/device/cuda/device_cuda_impl.cpp
@@ -359,6 +359,10 @@ string CUDADevice::compile_kernel_get_common_cflags(
     cflags += " -D__SPLIT__";
   }
 
+#  ifdef WITH_NANOVDB
+  cflags += " -DWITH_NANOVDB";
+#  endif
+
   return cflags;
 }
 
@@ -1253,42 +1257,6 @@ void CUDADevice::tex_alloc(device_texture &mem)
     cuda_assert(cuMemcpyHtoD(mem.device_pointer, mem.host_pointer, size));
   }
 
-  /* Kepler+, bindless textures. */
-  CUDA_RESOURCE_DESC resDesc;
-  memset(&resDesc, 0, sizeof(resDesc));
-
-  if (array_3d) {
-    resDesc.resType = CU_RESOURCE_TYPE_ARRAY;
-    resDesc.res.array.hArray = array_3d;
-    resDesc.flags = 0;
-  }
-  else if (mem.data_height > 0) {
-    resDesc.resType = CU_RESOURCE_TYPE_PITCH2D;
-    resDesc.res.pitch2D.devPtr = mem.device_pointer;
-    resDesc.res.pitch2D.format = format;
-    resDesc.res.pitch2D.numChannels = mem.data_elements;
-    resDesc.res.pitch2D.height = mem.data_height;
-    resDesc.res.pitch2D.width = mem.data_width;
-    resDesc.res.pitch2D.pitchInBytes = dst_pitch;
-  }
-  else {
-    resDesc.resType = CU_RESOURCE_TYPE_LINEAR;
-    resDesc.res.linear.devPtr = mem.device_pointer;
-    resDesc.res.linear.format = format;
-    resDesc.res.linear.numChannels = mem.data_elements;
-    resDesc.res.linear.sizeInBytes = mem.device_size;
-  }
-
-  CUDA_TEXTURE_DESC texDesc;
-  memset(&texDesc, 0, sizeof(texDesc));
-  texDesc.addressMode[0] = address_mode;
-  texDesc.addressMode[1] = address_mode;
-  texDesc.addressMode[2] = address_mode;
-  texDesc.filterMode = filter_mode;
-  texDesc.flags = CU_TRSF_NORMALIZED_COORDINATES;
-
-  cuda_assert(cuTexObjectCreate(&cmem->texobject, &resDesc, &texDesc, NULL));
-
   /* Resize once */
   const uint slot = mem.slot;
   if (slot >= texture_info.size()) {
@@ -1299,8 +1267,51 @@ void CUDADevice::tex_alloc(device_texture &mem)
 
   /* Set Mapping and tag that we need to (re-)upload to device */
   texture_info[slot] = mem.info;
-  texture_info[slot].data = (uint64_t)cmem->texobject;
   need_texture_info = true;
+
+  if (mem.info.data_type != IMAGE_DATA_TYPE_NANOVDB_FLOAT &&
+      mem.info.data_type != IMAGE_DATA_TYPE_NANOVDB_FLOAT3) {
+    /* Kepler+, bindless textures. */
+    CUDA_RESOURCE_DESC resDesc;
+    memset(&resDesc, 0, sizeof(resDesc));
+
+    if (array_3d) {
+      resDesc.resType = CU_RESOURCE_TYPE_ARRAY;
+      resDesc.res.array.hArray = array_3d;
+      resDesc.flags = 0;
+    }
+    else if (mem.data_height > 0) {
+      resDesc.resType = CU_RESOURCE_TYPE_PITCH2D;
+      resDesc.res.pitch2D.devPtr = mem.device_pointer;
+      resDesc.res.pitch2D.format = format;
+      resDesc.res.pitch2D.numChannels = mem.data_elements;
+      resDesc.res.pitch2D.height = mem.data_height;
+      resDesc.res.pitch2D.width = mem.data_width;
+      resDesc.res.pitch2D.pitchInBytes = dst_pitch;
+    }
+    else {
+      resDesc.resType = CU_RESOURCE_TYPE_LINEAR;
+      resDesc.res.linear.devPtr = mem.device_pointer;
+      resDesc.res.linear.format = format;
+      resDesc.res.linear.numChannels = mem.data_elements;
+      resDesc.res.linear.sizeInBytes = mem.device_size;
+    }
+
+    CUDA_TEXTURE_DESC texDesc;
+    memset(&texDesc, 0, sizeof(texDesc));
+    texDesc.addressMode[0] = address_mode;
+    texDesc.addressMode[1] = address_mode;
+    texDesc.addressMode[2] = address_mode;
+    texDesc.filterMode = filter_mode;
+    texDesc.flags = CU_TRSF_NORMALIZED_COORDINATES;
+
+    cuda_assert(cuTexObjectCreate(&cmem->texobject, &resDesc, &texDesc, NULL));
+
+    texture_info[slot].data = (uint64_t)cmem->texobject;
+  }
+  else {
+    texture_info[slot].data = (uint64_t)mem.device_pointer;
+  }
 }
 
 void CUDADevice::tex_free(device_texture &mem)