diff options
4 files changed, 48 insertions, 1 deletions
diff --git a/source/blender/io/wavefront_obj/exporter/obj_export_file_writer.cc b/source/blender/io/wavefront_obj/exporter/obj_export_file_writer.cc index 302b20783c2..24a1b61d104 100644 --- a/source/blender/io/wavefront_obj/exporter/obj_export_file_writer.cc +++ b/source/blender/io/wavefront_obj/exporter/obj_export_file_writer.cc @@ -325,7 +325,12 @@ void OBJWriter::write_poly_elements(const OBJMesh &obj_mesh_data, obj_mesh_data.tot_uv_vertices()); const int tot_polygons = obj_mesh_data.tot_polygons(); - for (int i = 0; i < tot_polygons; i++) { + for (int idx = 0; idx < tot_polygons; idx++) { + /* Polygon order for writing into the file is not necessarily the same + * as order in the mesh; it will be sorted by material indices. Remap current + * index here according to the order. */ + int i = obj_mesh_data.remap_poly_index(idx); + Vector<int> poly_vertex_indices = obj_mesh_data.calc_poly_vertex_indices(i); Span<int> poly_uv_indices = obj_mesh_data.calc_poly_uv_indices(i); Vector<int> poly_normal_indices = obj_mesh_data.calc_poly_normal_indices(i); diff --git a/source/blender/io/wavefront_obj/exporter/obj_export_mesh.cc b/source/blender/io/wavefront_obj/exporter/obj_export_mesh.cc index fd831aa5674..93aba14aa0b 100644 --- a/source/blender/io/wavefront_obj/exporter/obj_export_mesh.cc +++ b/source/blender/io/wavefront_obj/exporter/obj_export_mesh.cc @@ -195,6 +195,25 @@ void OBJMesh::calc_smooth_groups(const bool use_bitflags) use_bitflags); } +void OBJMesh::calc_poly_order() +{ + const int tot_polys = tot_polygons(); + poly_order_.resize(tot_polys); + for (int i = 0; i < tot_polys; ++i) { + poly_order_[i] = i; + } + const MPoly *mpolys = export_mesh_eval_->mpoly; + /* Sort polygons by their material index. */ + std::sort(poly_order_.begin(), poly_order_.end(), [&](int a, int b) { + int mat_a = mpolys[a].mat_nr; + int mat_b = mpolys[b].mat_nr; + if (mat_a != mat_b) { + return mat_a < mat_b; + } + return a < b; + }); +} + const Material *OBJMesh::get_object_material(const int16_t mat_nr) const { /** diff --git a/source/blender/io/wavefront_obj/exporter/obj_export_mesh.hh b/source/blender/io/wavefront_obj/exporter/obj_export_mesh.hh index 3ec670d2203..4ab7567aa0f 100644 --- a/source/blender/io/wavefront_obj/exporter/obj_export_mesh.hh +++ b/source/blender/io/wavefront_obj/exporter/obj_export_mesh.hh @@ -101,6 +101,10 @@ class OBJMesh : NonCopyable { * Polygon aligned array of their smooth groups. */ int *poly_smooth_groups_ = nullptr; + /** + * Order in which the polygons should be written into the file (sorted by material index). + */ + Vector<int> poly_order_; public: /** @@ -212,6 +216,22 @@ class OBJMesh : NonCopyable { */ std::optional<std::array<int, 2>> calc_loose_edge_vert_indices(int edge_index) const; + /** + * Calculate the order in which the polygons should be written into the file (sorted by material + * index). + */ + void calc_poly_order(); + + /** + * Remap polygon index according to polygon writing order. + * When materials are not being written, the polygon order array + * might be empty, in which case remap is a no-op. + */ + int remap_poly_index(int i) const + { + return i < 0 || i >= poly_order_.size() ? i : poly_order_[i]; + } + private: /** * Free the mesh if _the exporter_ created it. diff --git a/source/blender/io/wavefront_obj/exporter/obj_exporter.cc b/source/blender/io/wavefront_obj/exporter/obj_exporter.cc index 0c753ccdcac..330002df0a7 100644 --- a/source/blender/io/wavefront_obj/exporter/obj_exporter.cc +++ b/source/blender/io/wavefront_obj/exporter/obj_exporter.cc @@ -171,6 +171,9 @@ static void write_mesh_objects(Vector<std::unique_ptr<OBJMesh>> exportable_as_me if (export_params.export_smooth_groups) { obj_mesh->calc_smooth_groups(export_params.smooth_groups_bitflags); } + if (export_params.export_materials) { + obj_mesh->calc_poly_order(); + } if (export_params.export_normals) { obj_writer.write_poly_normals(*obj_mesh); } |