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/* SPDX-License-Identifier: GPL-2.0-or-later */
#include <vector>
#include "BLI_math_vec_types.hh"
#include "BLI_span.hh"
#include "BLI_utildefines.h"
#include "DNA_mesh_types.h"
#include "DNA_meshdata_types.h"
#include "DNA_volume_types.h"
#include "BKE_mesh.h"
#include "BKE_volume.h"
#ifdef WITH_OPENVDB
# include <openvdb/tools/GridTransformer.h>
# include <openvdb/tools/VolumeToMesh.h>
#endif
#include "BKE_volume_to_mesh.hh"
namespace blender::bke {
#ifdef WITH_OPENVDB
struct VolumeToMeshOp {
const openvdb::GridBase &base_grid;
const VolumeToMeshResolution resolution;
const float threshold;
const float adaptivity;
std::vector<openvdb::Vec3s> verts;
std::vector<openvdb::Vec3I> tris;
std::vector<openvdb::Vec4I> quads;
template<typename GridType> bool operator()()
{
if constexpr (std::is_scalar_v<typename GridType::ValueType>) {
this->generate_mesh_data<GridType>();
return true;
}
return false;
}
template<typename GridType> void generate_mesh_data()
{
const GridType &grid = static_cast<const GridType &>(base_grid);
if (this->resolution.mode == VOLUME_TO_MESH_RESOLUTION_MODE_GRID) {
this->grid_to_mesh(grid);
return;
}
const float resolution_factor = this->compute_resolution_factor(base_grid);
typename GridType::Ptr temp_grid = this->create_grid_with_changed_resolution(
grid, resolution_factor);
this->grid_to_mesh(*temp_grid);
}
template<typename GridType>
typename GridType::Ptr create_grid_with_changed_resolution(const GridType &old_grid,
const float resolution_factor)
{
BLI_assert(resolution_factor > 0.0f);
openvdb::Mat4R xform;
xform.setToScale(openvdb::Vec3d(resolution_factor));
openvdb::tools::GridTransformer transformer{xform};
typename GridType::Ptr new_grid = GridType::create();
transformer.transformGrid<openvdb::tools::BoxSampler>(old_grid, *new_grid);
new_grid->transform() = old_grid.transform();
new_grid->transform().preScale(1.0f / resolution_factor);
return new_grid;
}
float compute_resolution_factor(const openvdb::GridBase &grid) const
{
const openvdb::Vec3s voxel_size{grid.voxelSize()};
const float current_voxel_size = std::max({voxel_size[0], voxel_size[1], voxel_size[2]});
const float desired_voxel_size = this->compute_desired_voxel_size(grid);
return current_voxel_size / desired_voxel_size;
}
float compute_desired_voxel_size(const openvdb::GridBase &grid) const
{
if (this->resolution.mode == VOLUME_TO_MESH_RESOLUTION_MODE_VOXEL_SIZE) {
return this->resolution.settings.voxel_size;
}
const openvdb::CoordBBox coord_bbox = base_grid.evalActiveVoxelBoundingBox();
const openvdb::BBoxd bbox = grid.transform().indexToWorld(coord_bbox);
const float max_extent = bbox.extents()[bbox.maxExtent()];
const float voxel_size = max_extent / this->resolution.settings.voxel_amount;
return voxel_size;
}
template<typename GridType> void grid_to_mesh(const GridType &grid)
{
openvdb::tools::volumeToMesh(
grid, this->verts, this->tris, this->quads, this->threshold, this->adaptivity);
/* Better align generated mesh with volume (see T85312). */
openvdb::Vec3s offset = grid.voxelSize() / 2.0f;
for (openvdb::Vec3s &position : this->verts) {
position += offset;
}
}
};
void fill_mesh_from_openvdb_data(const Span<openvdb::Vec3s> vdb_verts,
const Span<openvdb::Vec3I> vdb_tris,
const Span<openvdb::Vec4I> vdb_quads,
const int vert_offset,
const int poly_offset,
const int loop_offset,
MutableSpan<MVert> verts,
MutableSpan<MPoly> polys,
MutableSpan<MLoop> loops)
{
/* Write vertices. */
for (const int i : vdb_verts.index_range()) {
const blender::float3 co = blender::float3(vdb_verts[i].asV());
copy_v3_v3(verts[vert_offset + i].co, co);
}
/* Write triangles. */
for (const int i : vdb_tris.index_range()) {
polys[poly_offset + i].loopstart = loop_offset + 3 * i;
polys[poly_offset + i].totloop = 3;
for (int j = 0; j < 3; j++) {
/* Reverse vertex order to get correct normals. */
loops[loop_offset + 3 * i + j].v = vert_offset + vdb_tris[i][2 - j];
}
}
/* Write quads. */
const int quad_offset = poly_offset + vdb_tris.size();
const int quad_loop_offset = loop_offset + vdb_tris.size() * 3;
for (const int i : vdb_quads.index_range()) {
polys[quad_offset + i].loopstart = quad_loop_offset + 4 * i;
polys[quad_offset + i].totloop = 4;
for (int j = 0; j < 4; j++) {
/* Reverse vertex order to get correct normals. */
loops[quad_loop_offset + 4 * i + j].v = vert_offset + vdb_quads[i][3 - j];
}
}
}
bke::OpenVDBMeshData volume_to_mesh_data(const openvdb::GridBase &grid,
const VolumeToMeshResolution &resolution,
const float threshold,
const float adaptivity)
{
const VolumeGridType grid_type = BKE_volume_grid_type_openvdb(grid);
VolumeToMeshOp to_mesh_op{grid, resolution, threshold, adaptivity};
if (!BKE_volume_grid_type_operation(grid_type, to_mesh_op)) {
return {};
}
return {std::move(to_mesh_op.verts), std::move(to_mesh_op.tris), std::move(to_mesh_op.quads)};
}
Mesh *volume_to_mesh(const openvdb::GridBase &grid,
const VolumeToMeshResolution &resolution,
const float threshold,
const float adaptivity)
{
const bke::OpenVDBMeshData mesh_data = volume_to_mesh_data(
grid, resolution, threshold, adaptivity);
const int tot_loops = 3 * mesh_data.tris.size() + 4 * mesh_data.quads.size();
const int tot_polys = mesh_data.tris.size() + mesh_data.quads.size();
Mesh *mesh = BKE_mesh_new_nomain(mesh_data.verts.size(), 0, 0, tot_loops, tot_polys);
fill_mesh_from_openvdb_data(mesh_data.verts,
mesh_data.tris,
mesh_data.quads,
0,
0,
0,
mesh->verts_for_write(),
mesh->polys_for_write(),
mesh->loops_for_write());
BKE_mesh_calc_edges(mesh, false, false);
return mesh;
}
#endif /* WITH_OPENVDB */
} // namespace blender::bke
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