Cycles: support rendering new Volume object type

Voxels are loaded directly from the OpenVDB grid. Rendering still only supports
dense grid, so memory usage is not great for sparse volumes, this is to be
addressed in the future.

Ref T73201

intern/cycles/CMakeLists.txt

@@ -350,17 +350,6 @@ if(WITH_CYCLES_NETWORK)
   add_definitions(-DWITH_NETWORK)
 endif()
 
-if(WITH_OPENCOLORIO)
-  add_definitions(-DWITH_OCIO)
-  include_directories(
-    SYSTEM
-    ${OPENCOLORIO_INCLUDE_DIRS}
-  )
-  if(WIN32)
-    add_definitions(-DOpenColorIO_STATIC)
-  endif()
-endif()
-
 if(WITH_CYCLES_STANDALONE OR WITH_CYCLES_NETWORK OR WITH_CYCLES_CUBIN_COMPILER)
   add_subdirectory(app)
 endif()

intern/cycles/app/CMakeLists.txt

@@ -60,6 +60,7 @@ link_directories(
   ${TIFF_LIBPATH}
   ${OPENEXR_LIBPATH}
   ${OPENJPEG_LIBPATH}
+  ${OPENVDB_LIBPATH}
 )
 
 if(WITH_OPENCOLORIO)

intern/cycles/blender/CMakeLists.txt

@@ -92,6 +92,20 @@ if(WITH_MOD_FLUID)
   add_definitions(-DWITH_FLUID)
 endif()
 
+if(WITH_NEW_OBJECT_TYPES)
+  add_definitions(-DWITH_NEW_OBJECT_TYPES)
+endif()
+
+if(WITH_OPENVDB)
+  add_definitions(-DWITH_OPENVDB ${OPENVDB_DEFINITIONS})
+  list(APPEND INC_SYS
+    ${OPENVDB_INCLUDE_DIRS}
+  )
+  list(APPEND LIB
+    ${OPENVDB_LIBRARIES}
+  )
+endif()
+
 blender_add_lib(bf_intern_cycles "${SRC}" "${INC}" "${INC_SYS}" "${LIB}")
 
 # avoid link failure with clang 3.4 debug

intern/cycles/blender/blender_geometry.cpp

@@ -38,7 +38,8 @@ Geometry *BlenderSync::sync_geometry(BL::Depsgraph &b_depsgraph,
   BL::ID b_key_id = (BKE_object_is_modified(b_ob)) ? b_ob_instance : b_ob_data;
   GeometryKey key(b_key_id.ptr.data, use_particle_hair);
   BL::Material material_override = view_layer.material_override;
-  Shader *default_shader = scene->default_surface;
+  Shader *default_shader = (b_ob.type() == BL::Object::type_VOLUME) ? scene->default_volume :
+                                                                      scene->default_surface;
   Geometry::Type geom_type = (use_particle_hair &&
                               (scene->curve_system_manager->primitive != CURVE_TRIANGLES)) ?
                                  Geometry::HAIR :
@@ -124,7 +125,7 @@ Geometry *BlenderSync::sync_geometry(BL::Depsgraph &b_depsgraph,
   if (use_particle_hair) {
     sync_hair(b_depsgraph, b_ob, geom, used_shaders);
   }
-  else if (object_fluid_gas_domain_find(b_ob)) {
+  else if (b_ob.type() == BL::Object::type_VOLUME || object_fluid_gas_domain_find(b_ob)) {
     Mesh *mesh = static_cast<Mesh *>(geom);
     sync_volume(b_ob, mesh, used_shaders);
   }
@@ -164,7 +165,7 @@ void BlenderSync::sync_geometry_motion(BL::Depsgraph &b_depsgraph,
   if (use_particle_hair) {
     sync_hair_motion(b_depsgraph, b_ob, geom, motion_step);
   }
-  else if (object_fluid_gas_domain_find(b_ob)) {
+  else if (b_ob.type() == BL::Object::type_VOLUME || object_fluid_gas_domain_find(b_ob)) {
     /* No volume motion blur support yet. */
   }
   else {

intern/cycles/blender/blender_object.cpp

@@ -67,10 +67,16 @@ bool BlenderSync::object_is_mesh(BL::Object &b_ob)
     return false;
   }
 
-  if (b_ob.type() == BL::Object::type_CURVE) {
+  BL::Object::type_enum type = b_ob.type();
+
+  if (type == BL::Object::type_VOLUME) {
+    /* Will be exported attached to mesh. */
+    return true;
+  }
+  else if (type == BL::Object::type_CURVE) {
     /* Skip exporting curves without faces, overhead can be
      * significant if there are many for path animation. */
-    BL::Curve b_curve(b_ob.data());
+    BL::Curve b_curve(b_ob_data);
 
     return (b_curve.bevel_object() || b_curve.extrude() != 0.0f || b_curve.bevel_depth() != 0.0f ||
             b_curve.dimensions() == BL::Curve::dimensions_2D || b_ob.modifiers.length());

intern/cycles/blender/blender_sync.cpp

@@ -178,6 +178,11 @@ void BlenderSync::sync_recalc(BL::Depsgraph &b_depsgraph, BL::SpaceView3D &b_v3d
         world_recalc = true;
       }
     }
+    /* Volume */
+    else if (b_id.is_a(&RNA_Volume)) {
+      BL::Volume b_volume(b_id);
+      geometry_map.set_recalc(b_volume);
+    }
   }
 
   BlenderViewportParameters new_viewport_parameters(b_v3d);

intern/cycles/blender/blender_volume.cpp

@@ -16,12 +16,19 @@
 
 #include "render/colorspace.h"
 #include "render/image.h"
+#include "render/image_vdb.h"
 #include "render/mesh.h"
 #include "render/object.h"
 
 #include "blender/blender_sync.h"
 #include "blender/blender_util.h"
 
+#ifdef WITH_OPENVDB
+#  include <openvdb/openvdb.h>
+openvdb::GridBase::ConstPtr BKE_volume_grid_openvdb_for_read(const struct Volume *volume,
+                                                             struct VolumeGrid *grid);
+#endif
+
 CCL_NAMESPACE_BEGIN
 
 /* TODO: verify this is not loading unnecessary attributes. */
@@ -210,19 +217,121 @@ static void sync_smoke_volume(Scene *scene, BL::Object &b_ob, Mesh *mesh, float
 
     attr->data_voxel() = scene->image_manager->add_image(loader, params);
   }
+}
 
-  /* Create a matrix to transform from object space to mesh texture space.
-   * This does not work with deformations but that can probably only be done
-   * well with a volume grid mapping of coordinates. */
-  if (mesh->need_attribute(scene, ATTR_STD_GENERATED_TRANSFORM)) {
-    Attribute *attr = mesh->attributes.add(ATTR_STD_GENERATED_TRANSFORM);
-    Transform *tfm = attr->data_transform();
+class BlenderVolumeLoader : public VDBImageLoader {
+ public:
+  BlenderVolumeLoader(BL::Volume b_volume, const string &grid_name)
+      : VDBImageLoader(grid_name),
+        b_volume(b_volume),
+        b_volume_grid(PointerRNA_NULL),
+        unload(false)
+  {
+#ifdef WITH_OPENVDB
+    /* Find grid with matching name. */
+    BL::Volume::grids_iterator b_grid_iter;
+    for (b_volume.grids.begin(b_grid_iter); b_grid_iter != b_volume.grids.end(); ++b_grid_iter) {
+      if (b_grid_iter->name() == grid_name) {
+        b_volume_grid = *b_grid_iter;
+      }
+    }
+#endif
+  }
 
-    BL::Mesh b_mesh(b_ob.data());
-    float3 loc, size;
-    mesh_texture_space(b_mesh, loc, size);
+  bool load_metadata(ImageMetaData &metadata) override
+  {
+    if (!b_volume_grid) {
+      return false;
+    }
 
-    *tfm = transform_translate(-loc) * transform_scale(size);
+    unload = !b_volume_grid.is_loaded();
+
+#ifdef WITH_OPENVDB
+    Volume *volume = (Volume *)b_volume.ptr.data;
+    VolumeGrid *volume_grid = (VolumeGrid *)b_volume_grid.ptr.data;
+    grid = BKE_volume_grid_openvdb_for_read(volume, volume_grid);
+#endif
+
+    return VDBImageLoader::load_metadata(metadata);
+  }
+
+  bool load_pixels(const ImageMetaData &metadata,
+                   void *pixels,
+                   const size_t pixel_size,
+                   const bool associate_alpha) override
+  {
+    if (!b_volume_grid) {
+      return false;
+    }
+
+    return VDBImageLoader::load_pixels(metadata, pixels, pixel_size, associate_alpha);
+  }
+
+  bool equals(const ImageLoader &other) const override
+  {
+    /* TODO: detect multiple volume datablocks with the same filepath. */
+    const BlenderVolumeLoader &other_loader = (const BlenderVolumeLoader &)other;
+    return b_volume == other_loader.b_volume && b_volume_grid == other_loader.b_volume_grid;
+  }
+
+  void cleanup() override
+  {
+    VDBImageLoader::cleanup();
+    if (b_volume_grid && unload) {
+      b_volume_grid.unload();
+    }
+  }
+
+  BL::Volume b_volume;
+  BL::VolumeGrid b_volume_grid;
+  bool unload;
+};
+
+static void sync_volume_object(BL::BlendData &b_data, BL::Object &b_ob, Scene *scene, Mesh *mesh)
+{
+  BL::Volume b_volume(b_ob.data());
+  b_volume.grids.load(b_data.ptr.data);
+
+  mesh->volume_isovalue = 1e-3f; /* TODO: make user setting. */
+
+  /* Find grid with matching name. */
+  BL::Volume::grids_iterator b_grid_iter;
+  for (b_volume.grids.begin(b_grid_iter); b_grid_iter != b_volume.grids.end(); ++b_grid_iter) {
+    BL::VolumeGrid b_grid = *b_grid_iter;
+    ustring name = ustring(b_grid.name());
+    AttributeStandard std = ATTR_STD_NONE;
+
+    if (name == Attribute::standard_name(ATTR_STD_VOLUME_DENSITY)) {
+      std = ATTR_STD_VOLUME_DENSITY;
+    }
+    else if (name == Attribute::standard_name(ATTR_STD_VOLUME_COLOR)) {
+      std = ATTR_STD_VOLUME_COLOR;
+    }
+    else if (name == Attribute::standard_name(ATTR_STD_VOLUME_FLAME)) {
+      std = ATTR_STD_VOLUME_FLAME;
+    }
+    else if (name == Attribute::standard_name(ATTR_STD_VOLUME_HEAT)) {
+      std = ATTR_STD_VOLUME_HEAT;
+    }
+    else if (name == Attribute::standard_name(ATTR_STD_VOLUME_TEMPERATURE)) {
+      std = ATTR_STD_VOLUME_TEMPERATURE;
+    }
+    else if (name == Attribute::standard_name(ATTR_STD_VOLUME_VELOCITY)) {
+      std = ATTR_STD_VOLUME_VELOCITY;
+    }
+
+    if ((std != ATTR_STD_NONE && mesh->need_attribute(scene, std)) ||
+        mesh->need_attribute(scene, name)) {
+      Attribute *attr = (std != ATTR_STD_NONE) ?
+                            mesh->attributes.add(std) :
+                            mesh->attributes.add(name, TypeDesc::TypeFloat, ATTR_ELEMENT_VOXEL);
+
+      ImageLoader *loader = new BlenderVolumeLoader(b_volume, name.string());
+      ImageParams params;
+      params.frame = b_volume.grids.frame();
+
+      attr->data_voxel() = scene->image_manager->add_image(loader, params);
+    }
   }
 }
 
@@ -246,9 +355,16 @@ void BlenderSync::sync_volume(BL::Object &b_ob, Mesh *mesh, const vector<Shader
   mesh->clear();
   mesh->used_shaders = used_shaders;
 
-  /* Smoke domain. */
   if (view_layer.use_volumes) {
-    sync_smoke_volume(scene, b_ob, mesh, b_scene.frame_current());
+    if (b_ob.type() == BL::Object::type_VOLUME) {
+      /* Volume object. Create only attributes, bounding mesh will then
+       * be automatically generated later. */
+      sync_volume_object(b_data, b_ob, scene, mesh);
+    }
+    else {
+      /* Smoke domain. */
+      sync_smoke_volume(scene, b_ob, mesh, b_scene.frame_current());
+    }
   }
 
   /* Tag update. */

intern/cycles/render/CMakeLists.txt

@@ -24,6 +24,7 @@ set(SRC
   hair.cpp
   image.cpp
   image_oiio.cpp
+  image_vdb.cpp
   integrator.cpp
   jitter.cpp
   light.cpp
@@ -63,6 +64,7 @@ set(SRC_HEADERS
   hair.h
   image.h
   image_oiio.h
+  image_vdb.h
   integrator.h
   light.h
   jitter.h
@@ -98,6 +100,27 @@ if(WITH_CYCLES_OSL)
   SET_PROPERTY(SOURCE osl.cpp PROPERTY COMPILE_FLAGS ${RTTI_DISABLE_FLAGS})
 endif()
 
+if(WITH_OPENCOLORIO)
+  add_definitions(-DWITH_OCIO)
+  include_directories(
+    SYSTEM
+    ${OPENCOLORIO_INCLUDE_DIRS}
+  )
+  if(WIN32)
+    add_definitions(-DOpenColorIO_STATIC)
+  endif()
+endif()
+
+if(WITH_OPENVDB)
+  add_definitions(-DWITH_OPENVDB ${OPENVDB_DEFINITIONS})
+  list(APPEND INC_SYS
+    ${OPENVDB_INCLUDE_DIRS}
+  )
+  list(APPEND LIB
+    ${OPENVDB_LIBRARIES}
+  )
+endif()
+
 include_directories(${INC})
 include_directories(SYSTEM ${INC_SYS})
 

intern/cycles/render/image_vdb.cpp

@@ -0,0 +1,188 @@
+/*
+ * Copyright 2011-2020 Blender Foundation
+ *
+ * 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.
+ */
+
+#include "render/image_vdb.h"
+
+#ifdef WITH_OPENVDB
+#  include <openvdb/openvdb.h>
+#  include <openvdb/tools/Dense.h>
+#endif
+
+CCL_NAMESPACE_BEGIN
+
+VDBImageLoader::VDBImageLoader(const string &grid_name) : grid_name(grid_name)
+{
+}
+
+VDBImageLoader::~VDBImageLoader()
+{
+}
+
+bool VDBImageLoader::load_metadata(ImageMetaData &metadata)
+{
+#ifdef WITH_OPENVDB
+  if (!grid) {
+    return false;
+  }
+
+  bbox = grid->evalActiveVoxelBoundingBox();
+  if (bbox.empty()) {
+    return false;
+  }
+
+  /* Set dimensions. */
+  openvdb::Coord dim = bbox.dim();
+  openvdb::Coord min = bbox.min();
+  metadata.width = dim.x();
+  metadata.height = dim.y();
+  metadata.depth = dim.z();
+
+  /* Set data type. */
+  if (grid->isType<openvdb::FloatGrid>()) {
+    metadata.channels = 1;
+  }
+  else if (grid->isType<openvdb::Vec3fGrid>()) {
+    metadata.channels = 3;
+  }
+  else if (grid->isType<openvdb::BoolGrid>()) {
+    metadata.channels = 1;
+  }
+  else if (grid->isType<openvdb::DoubleGrid>()) {
+    metadata.channels = 1;
+  }
+  else if (grid->isType<openvdb::Int32Grid>()) {
+    metadata.channels = 1;
+  }
+  else if (grid->isType<openvdb::Int64Grid>()) {
+    metadata.channels = 1;
+  }
+  else if (grid->isType<openvdb::Vec3IGrid>()) {
+    metadata.channels = 3;
+  }
+  else if (grid->isType<openvdb::Vec3dGrid>()) {
+    metadata.channels = 3;
+  }
+  else if (grid->isType<openvdb::MaskGrid>()) {
+    metadata.channels = 1;
+  }
+  else {
+    return false;
+  }
+
+  if (metadata.channels == 1) {
+    metadata.type = IMAGE_DATA_TYPE_FLOAT;
+  }
+  else {
+    metadata.type = IMAGE_DATA_TYPE_FLOAT4;
+  }
+
+  /* Set transform from object space to voxel index. */
+  openvdb::math::Mat4f grid_matrix = grid->transform().baseMap()->getAffineMap()->getMat4();
+  Transform index_to_object;
+  for (int col = 0; col < 4; col++) {
+    for (int row = 0; row < 3; row++) {
+      index_to_object[row][col] = (float)grid_matrix[col][row];
+    }
+  }
+
+  Transform texture_to_index = transform_translate(min.x(), min.y(), min.z()) *
+                               transform_scale(dim.x(), dim.y(), dim.z());
+
+  metadata.transform_3d = transform_inverse(index_to_object * texture_to_index);
+  metadata.use_transform_3d = true;
+
+  return true;
+#else
+  (void)metadata;
+  return false;
+#endif
+}
+
+bool VDBImageLoader::load_pixels(const ImageMetaData &, void *pixels, const size_t, const bool)
+{
+#ifdef WITH_OPENVDB
+  if (grid->isType<openvdb::FloatGrid>()) {
+    openvdb::tools::Dense<float, openvdb::tools::LayoutXYZ> dense(bbox, (float *)pixels);
+    openvdb::tools::copyToDense(*openvdb::gridConstPtrCast<openvdb::FloatGrid>(grid), dense);
+  }
+  else if (grid->isType<openvdb::Vec3fGrid>()) {
+    openvdb::tools::Dense<openvdb::Vec3f, openvdb::tools::LayoutXYZ> dense(
+        bbox, (openvdb::Vec3f *)pixels);
+    openvdb::tools::copyToDense(*openvdb::gridConstPtrCast<openvdb::Vec3fGrid>(grid), dense);
+  }
+  else if (grid->isType<openvdb::BoolGrid>()) {
+    openvdb::tools::Dense<float, openvdb::tools::LayoutXYZ> dense(bbox, (float *)pixels);
+    openvdb::tools::copyToDense(*openvdb::gridConstPtrCast<openvdb::BoolGrid>(grid), dense);
+  }
+  else if (grid->isType<openvdb::DoubleGrid>()) {
+    openvdb::tools::Dense<float, openvdb::tools::LayoutXYZ> dense(bbox, (float *)pixels);
+    openvdb::tools::copyToDense(*openvdb::gridConstPtrCast<openvdb::DoubleGrid>(grid), dense);
+  }
+  else if (grid->isType<openvdb::Int32Grid>()) {
+    openvdb::tools::Dense<float, openvdb::tools::LayoutXYZ> dense(bbox, (float *)pixels);
+    openvdb::tools::copyToDense(*openvdb::gridConstPtrCast<openvdb::Int32Grid>(grid), dense);
+  }
+  else if (grid->isType<openvdb::Int64Grid>()) {
+    openvdb::tools::Dense<float, openvdb::tools::LayoutXYZ> dense(bbox, (float *)pixels);
+    openvdb::tools::copyToDense(*openvdb::gridConstPtrCast<openvdb::Int64Grid>(grid), dense);
+  }
+  else if (grid->isType<openvdb::Vec3IGrid>()) {
+    openvdb::tools::Dense<openvdb::Vec3f, openvdb::tools::LayoutXYZ> dense(
+        bbox, (openvdb::Vec3f *)pixels);
+    openvdb::tools::copyToDense(*openvdb::gridConstPtrCast<openvdb::Vec3IGrid>(grid), dense);
+  }
+  else if (grid->isType<openvdb::Vec3dGrid>()) {
+    openvdb::tools::Dense<openvdb::Vec3f, openvdb::tools::LayoutXYZ> dense(
+        bbox, (openvdb::Vec3f *)pixels);
+    openvdb::tools::copyToDense(*openvdb::gridConstPtrCast<openvdb::Vec3dGrid>(grid), dense);
+  }
+  else if (grid->isType<openvdb::MaskGrid>()) {
+    openvdb::tools::Dense<float, openvdb::tools::LayoutXYZ> dense(bbox, (float *)pixels);
+    openvdb::tools::copyToDense(*openvdb::gridConstPtrCast<openvdb::MaskGrid>(grid), dense);
+  }
+
+  return true;
+#else
+  (void)pixels;
+  return false;
+#endif
+}
+
+string VDBImageLoader::name() const
+{
+  return grid_name;
+}
+
+bool VDBImageLoader::equals(const ImageLoader &other) const
+{
+#ifdef WITH_OPENVDB
+  const VDBImageLoader &other_loader = (const VDBImageLoader &)other;
+  return grid == other_loader.grid;
+#else
+  (void)other;
+  return true;
+#endif
+}
+
+void VDBImageLoader::cleanup()
+{
+#ifdef WITH_OPENVDB
+  /* Free OpenVDB grid memory as soon as we can. */
+  grid.reset();
+#endif
+}
+
+CCL_NAMESPACE_END

intern/cycles/render/image_vdb.h

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2011-2020 Blender Foundation
+ *
+ * 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.
+ */
+
+#ifndef __IMAGE_VDB__
+#define __IMAGE_VDB__
+
+#ifdef WITH_OPENVDB
+#  include <openvdb/openvdb.h>
+#endif
+
+#include "render/image.h"
+
+CCL_NAMESPACE_BEGIN
+
+class VDBImageLoader : public ImageLoader {
+ public:
+  VDBImageLoader(const string &grid_name);
+  ~VDBImageLoader();
+
+  virtual bool load_metadata(ImageMetaData &metadata) override;
+
+  virtual bool load_pixels(const ImageMetaData &metadata,
+                           void *pixels,
+                           const size_t pixels_size,
+                           const bool associate_alpha) override;
+
+  virtual string name() const override;
+
+  virtual bool equals(const ImageLoader &other) const override;
+
+  virtual void cleanup() override;
+
+ protected:
+  string grid_name;
+#ifdef WITH_OPENVDB
+  openvdb::GridBase::ConstPtr grid;
+  openvdb::CoordBBox bbox;
+#endif
+};
+
+CCL_NAMESPACE_END
+
+#endif /* __IMAGE_VDB__ */

intern/cycles/test/CMakeLists.txt

@@ -82,6 +82,7 @@ list(APPEND ALL_CYCLES_LIBRARIES
   ${TIFF_LIBRARY}
   ${OPENIMAGEIO_LIBRARIES}
   ${OPENEXR_LIBRARIES}
+  ${OPENVDB_LIBRARIES}
 )
 
 include_directories(${INC})
@@ -95,6 +96,7 @@ link_directories(
   ${TIFF_LIBPATH}
   ${OPENEXR_LIBPATH}
   ${OPENCOLORIO_LIBPATH}
+  ${OPENVDB_LIBPATH}
 )
 
 set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${PLATFORM_LINKFLAGS}")