diff options
Diffstat (limited to 'source/blender/geometry/intern/mesh_to_volume.cc')
| -rw-r--r-- | source/blender/geometry/intern/mesh_to_volume.cc | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/source/blender/geometry/intern/mesh_to_volume.cc b/source/blender/geometry/intern/mesh_to_volume.cc new file mode 100644 index 00000000000..b1c7be38609 --- /dev/null +++ b/source/blender/geometry/intern/mesh_to_volume.cc @@ -0,0 +1,173 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +#include "BKE_mesh.h" +#include "BKE_mesh_runtime.h" +#include "BKE_volume.h" + +#include "GEO_mesh_to_volume.hh" + +#ifdef WITH_OPENVDB +# include <openvdb/openvdb.h> +# include <openvdb/tools/GridTransformer.h> +# include <openvdb/tools/VolumeToMesh.h> + +namespace blender::geometry { + +/* This class follows the MeshDataAdapter interface from openvdb. */ +class OpenVDBMeshAdapter { + private: + Span<MVert> verts_; + Span<MLoop> loops_; + Span<MLoopTri> looptris_; + float4x4 transform_; + + public: + OpenVDBMeshAdapter(const Mesh &mesh, float4x4 transform); + size_t polygonCount() const; + size_t pointCount() const; + size_t vertexCount(size_t UNUSED(polygon_index)) const; + void getIndexSpacePoint(size_t polygon_index, size_t vertex_index, openvdb::Vec3d &pos) const; +}; + +OpenVDBMeshAdapter::OpenVDBMeshAdapter(const Mesh &mesh, float4x4 transform) + : verts_(mesh.verts()), loops_(mesh.loops()), transform_(transform) +{ + /* This only updates a cache and can be considered to be logically const. */ + const MLoopTri *looptris = BKE_mesh_runtime_looptri_ensure(&mesh); + const int looptris_len = BKE_mesh_runtime_looptri_len(&mesh); + looptris_ = Span(looptris, looptris_len); +} + +size_t OpenVDBMeshAdapter::polygonCount() const +{ + return static_cast<size_t>(looptris_.size()); +} + +size_t OpenVDBMeshAdapter::pointCount() const +{ + return static_cast<size_t>(verts_.size()); +} + +size_t OpenVDBMeshAdapter::vertexCount(size_t UNUSED(polygon_index)) const +{ + /* All polygons are triangles. */ + return 3; +} + +void OpenVDBMeshAdapter::getIndexSpacePoint(size_t polygon_index, + size_t vertex_index, + openvdb::Vec3d &pos) const +{ + const MLoopTri &looptri = looptris_[polygon_index]; + const MVert &vertex = verts_[loops_[looptri.tri[vertex_index]].v]; + const float3 transformed_co = transform_ * float3(vertex.co); + pos = &transformed_co.x; +} + +float volume_compute_voxel_size(const Depsgraph *depsgraph, + FunctionRef<void(float3 &r_min, float3 &r_max)> bounds_fn, + const MeshToVolumeResolution res, + const float exterior_band_width, + const float4x4 &transform) +{ + const float volume_simplify = BKE_volume_simplify_factor(depsgraph); + if (volume_simplify == 0.0f) { + return 0.0f; + } + + if (res.mode == MESH_TO_VOLUME_RESOLUTION_MODE_VOXEL_SIZE) { + return res.settings.voxel_size / volume_simplify; + } + if (res.settings.voxel_amount <= 0) { + return 0; + } + + float3 bb_min; + float3 bb_max; + bounds_fn(bb_min, bb_max); + + /* Compute the voxel size based on the desired number of voxels and the approximated bounding + * box of the volume. */ + const float diagonal = math::distance(transform * bb_max, transform * bb_min); + const float approximate_volume_side_length = diagonal + exterior_band_width * 2.0f; + const float voxel_size = approximate_volume_side_length / res.settings.voxel_amount / + volume_simplify; + return voxel_size; +} + +static openvdb::FloatGrid::Ptr mesh_to_volume_grid(const Mesh *mesh, + const float4x4 &mesh_to_volume_space_transform, + const float voxel_size, + const bool fill_volume, + const float exterior_band_width, + const float interior_band_width, + const float density) +{ + if (voxel_size == 0.0f) { + return nullptr; + } + + float4x4 mesh_to_index_space_transform; + scale_m4_fl(mesh_to_index_space_transform.values, 1.0f / voxel_size); + mul_m4_m4_post(mesh_to_index_space_transform.values, mesh_to_volume_space_transform.values); + /* Better align generated grid with the source mesh. */ + add_v3_fl(mesh_to_index_space_transform.values[3], -0.5f); + + OpenVDBMeshAdapter mesh_adapter{*mesh, mesh_to_index_space_transform}; + + /* Convert the bandwidths from object in index space. */ + const float exterior = MAX2(0.001f, exterior_band_width / voxel_size); + const float interior = MAX2(0.001f, interior_band_width / voxel_size); + + openvdb::FloatGrid::Ptr new_grid; + if (fill_volume) { + /* Setting the interior bandwidth to FLT_MAX, will make it fill the entire volume. */ + new_grid = openvdb::tools::meshToVolume<openvdb::FloatGrid>( + mesh_adapter, {}, exterior, FLT_MAX); + } + else { + new_grid = openvdb::tools::meshToVolume<openvdb::FloatGrid>( + mesh_adapter, {}, exterior, interior); + } + + /* Give each grid cell a fixed density for now. */ + openvdb::tools::foreach ( + new_grid->beginValueOn(), + [density](const openvdb::FloatGrid::ValueOnIter &iter) { iter.setValue(density); }); + + return new_grid; +} + +VolumeGrid *volume_grid_add_from_mesh(Volume *volume, + const StringRefNull name, + const Mesh *mesh, + const float4x4 &mesh_to_volume_space_transform, + const float voxel_size, + const bool fill_volume, + const float exterior_band_width, + const float interior_band_width, + const float density) +{ + VolumeGrid *c_grid = BKE_volume_grid_add(volume, name.c_str(), VOLUME_GRID_FLOAT); + openvdb::FloatGrid::Ptr grid = openvdb::gridPtrCast<openvdb::FloatGrid>( + BKE_volume_grid_openvdb_for_write(volume, c_grid, false)); + + /* Generate grid from mesh */ + openvdb::FloatGrid::Ptr mesh_grid = mesh_to_volume_grid(mesh, + mesh_to_volume_space_transform, + voxel_size, + fill_volume, + exterior_band_width, + interior_band_width, + density); + + /* Merge the generated grid. Should be cheap because grid has just been created. */ + grid->merge(*mesh_grid); + /* Set class to "Fog Volume". */ + grid->setGridClass(openvdb::GRID_FOG_VOLUME); + /* Change transform so that the index space is correctly transformed to object space. */ + grid->transform().postScale(voxel_size); + return c_grid; +} +} // namespace blender::geometry +#endif |