From 3a1e6bc1d5807b732536c73170f11268fb398726 Mon Sep 17 00:00:00 2001 From: Aras Pranckevicius Date: Sat, 19 Mar 2022 16:20:22 -0400 Subject: Fix T96430: new OBJ exporter wrong normals for non-uniform scale, and wrong face order for negative scale The new 3.1+ OBJ exporter did not have correct logic when faced with non-uniform & mirrored (negative on odd number of axes) object scale: - Normals were not transformed correctly (should use inverse transpose of the matrix), and were not normalized, - Face order was not "flipped" when transform has negative scale on odd number of axes (visible when using "face orientation" viewport overlay). Cherry-picked from 8aa365745a78, with minor conflict fixes. Reviewed By: Howard Trickey Differential Revision: https://developer.blender.org/D14343 --- .../exporter/obj_export_file_writer.cc | 98 +++++++++++++++++----- .../exporter/obj_export_file_writer.hh | 15 ++-- .../io/wavefront_obj/exporter/obj_export_mesh.cc | 13 ++- .../io/wavefront_obj/exporter/obj_export_mesh.hh | 6 ++ .../io/wavefront_obj/tests/obj_exporter_tests.cc | 10 +++ 5 files changed, 114 insertions(+), 28 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 38163af64b6..4eea2e51521 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 @@ -54,56 +54,109 @@ const char *MATERIAL_GROUP_DISABLED = ""; void OBJWriter::write_vert_uv_normal_indices(Span vert_indices, Span uv_indices, - Span normal_indices) const + Span normal_indices, + bool flip) const { BLI_assert(vert_indices.size() == uv_indices.size() && vert_indices.size() == normal_indices.size()); + const int vertex_offset = index_offsets_.vertex_offset + 1; + const int uv_offset = index_offsets_.uv_vertex_offset + 1; + const int normal_offset = index_offsets_.normal_offset + 1; + const int n = vert_indices.size(); file_handler_->write(); - for (int j = 0; j < vert_indices.size(); j++) { - file_handler_->write( - vert_indices[j] + index_offsets_.vertex_offset + 1, - uv_indices[j] + index_offsets_.uv_vertex_offset + 1, - normal_indices[j] + index_offsets_.normal_offset + 1); + if (!flip) { + for (int j = 0; j < n; ++j) { + file_handler_->write( + vert_indices[j] + vertex_offset, + uv_indices[j] + uv_offset, + normal_indices[j] + normal_offset); + } + } + else { + /* For a transform that is mirrored (negative scale on odd number of axes), + * we want to flip the face index order. Start from the same index, and + * then go backwards. Same logic in other write_*_indices functions below. */ + for (int k = 0; k < n; ++k) { + int j = k == 0 ? 0 : n - k; + file_handler_->write( + vert_indices[j] + vertex_offset, + uv_indices[j] + uv_offset, + normal_indices[j] + normal_offset); + } } file_handler_->write(); } void OBJWriter::write_vert_normal_indices(Span vert_indices, Span /*uv_indices*/, - Span normal_indices) const + Span normal_indices, + bool flip) const { BLI_assert(vert_indices.size() == normal_indices.size()); + const int vertex_offset = index_offsets_.vertex_offset + 1; + const int normal_offset = index_offsets_.normal_offset + 1; + const int n = vert_indices.size(); file_handler_->write(); - for (int j = 0; j < vert_indices.size(); j++) { - file_handler_->write( - vert_indices[j] + index_offsets_.vertex_offset + 1, - normal_indices[j] + index_offsets_.normal_offset + 1); + if (!flip) { + for (int j = 0; j < n; ++j) { + file_handler_->write( + vert_indices[j] + vertex_offset, normal_indices[j] + normal_offset); + } + } + else { + for (int k = 0; k < n; ++k) { + int j = k == 0 ? 0 : n - k; + file_handler_->write( + vert_indices[j] + vertex_offset, normal_indices[j] + normal_offset); + } } file_handler_->write(); } void OBJWriter::write_vert_uv_indices(Span vert_indices, Span uv_indices, - Span /*normal_indices*/) const + Span /*normal_indices*/, + bool flip) const { BLI_assert(vert_indices.size() == uv_indices.size()); + const int vertex_offset = index_offsets_.vertex_offset + 1; + const int uv_offset = index_offsets_.uv_vertex_offset + 1; + const int n = vert_indices.size(); file_handler_->write(); - for (int j = 0; j < vert_indices.size(); j++) { - file_handler_->write( - vert_indices[j] + index_offsets_.vertex_offset + 1, - uv_indices[j] + index_offsets_.uv_vertex_offset + 1); + if (!flip) { + for (int j = 0; j < n; ++j) { + file_handler_->write(vert_indices[j] + vertex_offset, + uv_indices[j] + uv_offset); + } + } + else { + for (int k = 0; k < n; ++k) { + int j = k == 0 ? 0 : n - k; + file_handler_->write(vert_indices[j] + vertex_offset, + uv_indices[j] + uv_offset); + } } file_handler_->write(); } void OBJWriter::write_vert_indices(Span vert_indices, Span /*uv_indices*/, - Span /*normal_indices*/) const + Span /*normal_indices*/, + bool flip) const { + const int vertex_offset = index_offsets_.vertex_offset + 1; + const int n = vert_indices.size(); file_handler_->write(); - for (const int vert_index : vert_indices) { - file_handler_->write(vert_index + - index_offsets_.vertex_offset + 1); + if (!flip) { + for (int j = 0; j < n; ++j) { + file_handler_->write(vert_indices[j] + vertex_offset); + } + } + else { + for (int k = 0; k < n; ++k) { + int j = k == 0 ? 0 : n - k; + file_handler_->write(vert_indices[j] + vertex_offset); + } } file_handler_->write(); } @@ -297,7 +350,10 @@ void OBJWriter::write_poly_elements(const OBJMesh &obj_mesh_data, last_poly_smooth_group = write_smooth_group(obj_mesh_data, i, last_poly_smooth_group); last_poly_vertex_group = write_vertex_group(obj_mesh_data, i, last_poly_vertex_group); last_poly_mat_nr = write_poly_material(obj_mesh_data, i, last_poly_mat_nr, matname_fn); - (this->*poly_element_writer)(poly_vertex_indices, poly_uv_indices, poly_normal_indices); + (this->*poly_element_writer)(poly_vertex_indices, + poly_uv_indices, + poly_normal_indices, + obj_mesh_data.is_mirrored_transform()); } } diff --git a/source/blender/io/wavefront_obj/exporter/obj_export_file_writer.hh b/source/blender/io/wavefront_obj/exporter/obj_export_file_writer.hh index 7385d9fabe2..1bbdb7a848c 100644 --- a/source/blender/io/wavefront_obj/exporter/obj_export_file_writer.hh +++ b/source/blender/io/wavefront_obj/exporter/obj_export_file_writer.hh @@ -135,7 +135,8 @@ class OBJWriter : NonMovable, NonCopyable { private: using func_vert_uv_normal_indices = void (OBJWriter::*)(Span vert_indices, Span uv_indices, - Span normal_indices) const; + Span normal_indices, + bool flip) const; /** * \return Writer function with appropriate polygon-element syntax. */ @@ -146,25 +147,29 @@ class OBJWriter : NonMovable, NonCopyable { */ void write_vert_uv_normal_indices(Span vert_indices, Span uv_indices, - Span normal_indices) const; + Span normal_indices, + bool flip) const; /** * Write one line of polygon indices as "f v1//vn1 v2//vn2 ...". */ void write_vert_normal_indices(Span vert_indices, Span /*uv_indices*/, - Span normal_indices) const; + Span normal_indices, + bool flip) const; /** * Write one line of polygon indices as "f v1/vt1 v2/vt2 ...". */ void write_vert_uv_indices(Span vert_indices, Span uv_indices, - Span /*normal_indices*/) const; + Span /*normal_indices*/, + bool flip) const; /** * Write one line of polygon indices as "f v1 v2 ...". */ void write_vert_indices(Span vert_indices, Span /*uv_indices*/, - Span /*normal_indices*/) const; + Span /*normal_indices*/, + bool flip) const; }; /** 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 66f10009875..c1b9b0a8ccf 100644 --- a/source/blender/io/wavefront_obj/exporter/obj_export_mesh.cc +++ b/source/blender/io/wavefront_obj/exporter/obj_export_mesh.cc @@ -125,6 +125,13 @@ void OBJMesh::set_world_axes_transform(const eTransformAxisForward forward, /* mul_m4_m3m4 does not transform last row of obmat, i.e. location data. */ mul_v3_m3v3(world_and_axes_transform_[3], axes_transform, export_object_eval_.obmat[3]); world_and_axes_transform_[3][3] = export_object_eval_.obmat[3][3]; + + /* Normals need inverse transpose of the regular matrix to handle non-uniform scale. */ + float normal_matrix[3][3]; + copy_m3_m4(normal_matrix, world_and_axes_transform_); + invert_m3_m3(world_and_axes_normal_transform_, normal_matrix); + transpose_m3(world_and_axes_normal_transform_); + mirrored_transform_ = determinant_m3_array(world_and_axes_normal_transform_) < 0; } int OBJMesh::tot_vertices() const @@ -322,7 +329,8 @@ float3 OBJMesh::calc_poly_normal(const int poly_index) const const MLoop &mloop = export_mesh_eval_->mloop[poly.loopstart]; const MVert &mvert = *(export_mesh_eval_->mvert); BKE_mesh_calc_poly_normal(&poly, &mloop, &mvert, r_poly_normal); - mul_mat3_m4_v3(world_and_axes_transform_, r_poly_normal); + mul_m3_v3(world_and_axes_normal_transform_, r_poly_normal); + normalize_v3(r_poly_normal); return r_poly_normal; } @@ -367,7 +375,8 @@ void OBJMesh::store_normal_coords_and_indices(Vector &r_normal_coords) int loop_index = mpoly.loopstart + loop_of_poly; BLI_assert(loop_index < export_mesh_eval_->totloop); copy_v3_v3(loop_normal, lnors[loop_index]); - mul_mat3_m4_v3(world_and_axes_transform_, loop_normal); + mul_m3_v3(world_and_axes_normal_transform_, loop_normal); + normalize_v3(loop_normal); float3 rounded_loop_normal = round_float3_to_n_digits(loop_normal, round_digits); int loop_norm_index = normal_to_index.lookup_default(rounded_loop_normal, -1); if (loop_norm_index == -1) { 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 f3ace140006..3ec670d2203 100644 --- a/source/blender/io/wavefront_obj/exporter/obj_export_mesh.hh +++ b/source/blender/io/wavefront_obj/exporter/obj_export_mesh.hh @@ -73,6 +73,8 @@ class OBJMesh : NonCopyable { * object's world transform matrix. */ float world_and_axes_transform_[4][4]; + float world_and_axes_normal_transform_[3][3]; + bool mirrored_transform_; /** * Total UV vertices in a mesh's texture map. @@ -113,6 +115,10 @@ class OBJMesh : NonCopyable { int tot_uv_vertices() const; int tot_normal_indices() const; int tot_edges() const; + bool is_mirrored_transform() const + { + return mirrored_transform_; + } /** * \return Total materials in the object. diff --git a/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc b/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc index 48340b9eea8..7e60492bac2 100644 --- a/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc +++ b/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc @@ -373,6 +373,16 @@ TEST_F(obj_exporter_regression_test, vertices) "io_tests/blend_geometry/vertices.blend", "io_tests/obj/vertices.obj", "", _export.params); } +TEST_F(obj_exporter_regression_test, non_uniform_scale) +{ + OBJExportParamsDefault _export; + _export.params.export_materials = false; + compare_obj_export_to_golden("io_tests/blend_geometry/non_uniform_scale.blend", + "io_tests/obj/non_uniform_scale.obj", + "", + _export.params); +} + TEST_F(obj_exporter_regression_test, nurbs_as_nurbs) { OBJExportParamsDefault _export; 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