Add a new C++ version of an exporter for the Wavefront .obj format.

This was originally written by Ankit Meel as a GSoC 2020 project.
Howard Trickey added some tests and made some corrections/modifications.
See D13046 for more details.

This commit inserts a new menu item into the export menu called
"Wavefront OBJ (.obj) - New".
For now the old Python exporter remains in the menu, along with
the Python importer, but we plan to remove it soon (leaving the
old addon bundled with Blender but not enabled by default).

1 files changed, 417 insertions, 0 deletions

diff --git a/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc b/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
new file mode 100644
index 00000000000..f12bfd0cea5
--- /dev/null
+++ b/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
@@ -0,0 +1,417 @@
+/* Apache License, Version 2.0 */
+
+#include <fstream>
+#include <gtest/gtest.h>
+#include <ios>
+#include <memory>
+#include <sstream>
+#include <string>
+#include <system_error>
+
+#include "testing/testing.h"
+#include "tests/blendfile_loading_base_test.h"
+
+#include "BKE_appdir.h"
+#include "BKE_blender_version.h"
+
+#include "BLI_fileops.h"
+#include "BLI_index_range.hh"
+#include "BLI_string_utf8.h"
+#include "BLI_vector.hh"
+
+#include "DEG_depsgraph.h"
+
+#include "obj_export_file_writer.hh"
+#include "obj_export_mesh.hh"
+#include "obj_export_nurbs.hh"
+#include "obj_exporter.hh"
+
+#include "obj_exporter_tests.hh"
+
+namespace blender::io::obj {
+
+/* This is also the test name. */
+class obj_exporter_test : public BlendfileLoadingBaseTest {
+ public:
+  /**
+   * \param filepath: relative to "tests" directory.
+   */
+  bool load_file_and_depsgraph(const std::string &filepath,
+                               const eEvaluationMode eval_mode = DAG_EVAL_VIEWPORT)
+  {
+    if (!blendfile_load(filepath.c_str())) {
+      return false;
+    }
+    depsgraph_create(eval_mode);
+    return true;
+  }
+};
+
+const std::string all_objects_file = "io_tests/blend_scene/all_objects.blend";
+const std::string all_curve_objects_file = "io_tests/blend_scene/all_curves.blend";
+
+TEST_F(obj_exporter_test, filter_objects_curves_as_mesh)
+{
+  OBJExportParamsDefault _export;
+  if (!load_file_and_depsgraph(all_objects_file)) {
+    ADD_FAILURE();
+    return;
+  }
+  auto [objmeshes, objcurves]{filter_supported_objects(depsgraph, _export.params)};
+  EXPECT_EQ(objmeshes.size(), 17);
+  EXPECT_EQ(objcurves.size(), 0);
+}
+
+TEST_F(obj_exporter_test, filter_objects_curves_as_nurbs)
+{
+  OBJExportParamsDefault _export;
+  if (!load_file_and_depsgraph(all_objects_file)) {
+    ADD_FAILURE();
+    return;
+  }
+  _export.params.export_curves_as_nurbs = true;
+  auto [objmeshes, objcurves]{filter_supported_objects(depsgraph, _export.params)};
+  EXPECT_EQ(objmeshes.size(), 16);
+  EXPECT_EQ(objcurves.size(), 2);
+}
+
+TEST_F(obj_exporter_test, filter_objects_selected)
+{
+  OBJExportParamsDefault _export;
+  if (!load_file_and_depsgraph(all_objects_file)) {
+    ADD_FAILURE();
+    return;
+  }
+  _export.params.export_selected_objects = true;
+  _export.params.export_curves_as_nurbs = true;
+  auto [objmeshes, objcurves]{filter_supported_objects(depsgraph, _export.params)};
+  EXPECT_EQ(objmeshes.size(), 1);
+  EXPECT_EQ(objcurves.size(), 0);
+}
+
+TEST(obj_exporter_utils, append_negative_frame_to_filename)
+{
+  const char path_original[FILE_MAX] = "/my_file.obj";
+  const char path_truth[FILE_MAX] = "/my_file-123.obj";
+  const int frame = -123;
+  char path_with_frame[FILE_MAX] = {0};
+  const bool ok = append_frame_to_filename(path_original, frame, path_with_frame);
+  EXPECT_TRUE(ok);
+  EXPECT_EQ_ARRAY(path_with_frame, path_truth, BLI_strlen_utf8(path_truth));
+}
+
+TEST(obj_exporter_utils, append_positive_frame_to_filename)
+{
+  const char path_original[FILE_MAX] = "/my_file.obj";
+  const char path_truth[FILE_MAX] = "/my_file123.obj";
+  const int frame = 123;
+  char path_with_frame[FILE_MAX] = {0};
+  const bool ok = append_frame_to_filename(path_original, frame, path_with_frame);
+  EXPECT_TRUE(ok);
+  EXPECT_EQ_ARRAY(path_with_frame, path_truth, BLI_strlen_utf8(path_truth));
+}
+
+TEST_F(obj_exporter_test, curve_nurbs_points)
+{
+  if (!load_file_and_depsgraph(all_curve_objects_file)) {
+    ADD_FAILURE();
+    return;
+  }
+
+  OBJExportParamsDefault _export;
+  _export.params.export_curves_as_nurbs = true;
+  auto [objmeshes_unused, objcurves]{filter_supported_objects(depsgraph, _export.params)};
+
+  for (auto &objcurve : objcurves) {
+    if (all_nurbs_truth.count(objcurve->get_curve_name()) != 1) {
+      ADD_FAILURE();
+      return;
+    }
+    const NurbsObject *const nurbs_truth = all_nurbs_truth.at(objcurve->get_curve_name()).get();
+    EXPECT_EQ(objcurve->total_splines(), nurbs_truth->total_splines());
+    for (int spline_index : IndexRange(objcurve->total_splines())) {
+      EXPECT_EQ(objcurve->total_spline_vertices(spline_index),
+                nurbs_truth->total_spline_vertices(spline_index));
+      EXPECT_EQ(objcurve->get_nurbs_degree(spline_index),
+                nurbs_truth->get_nurbs_degree(spline_index));
+      EXPECT_EQ(objcurve->total_spline_control_points(spline_index),
+                nurbs_truth->total_spline_control_points(spline_index));
+    }
+  }
+}
+
+TEST_F(obj_exporter_test, curve_coordinates)
+{
+  if (!load_file_and_depsgraph(all_curve_objects_file)) {
+    ADD_FAILURE();
+    return;
+  }
+
+  OBJExportParamsDefault _export;
+  _export.params.export_curves_as_nurbs = true;
+  auto [objmeshes_unused, objcurves]{filter_supported_objects(depsgraph, _export.params)};
+
+  for (auto &objcurve : objcurves) {
+    if (all_nurbs_truth.count(objcurve->get_curve_name()) != 1) {
+      ADD_FAILURE();
+      return;
+    }
+    const NurbsObject *const nurbs_truth = all_nurbs_truth.at(objcurve->get_curve_name()).get();
+    EXPECT_EQ(objcurve->total_splines(), nurbs_truth->total_splines());
+    for (int spline_index : IndexRange(objcurve->total_splines())) {
+      for (int vertex_index : IndexRange(objcurve->total_spline_vertices(spline_index))) {
+        EXPECT_V3_NEAR(objcurve->vertex_coordinates(
+                           spline_index, vertex_index, _export.params.scaling_factor),
+                       nurbs_truth->vertex_coordinates(spline_index, vertex_index),
+                       0.000001f);
+      }
+    }
+  }
+}
+
+static std::unique_ptr<OBJWriter> init_writer(const OBJExportParams &params,
+                                              const std::string out_filepath)
+{
+  try {
+    auto writer = std::make_unique<OBJWriter>(out_filepath.c_str(), params);
+    return writer;
+  }
+  catch (const std::system_error &ex) {
+    std::cerr << ex.code().category().name() << ": " << ex.what() << ": " << ex.code().message()
+              << std::endl;
+    return nullptr;
+  }
+}
+
+/* The following is relative to BKE_tempdir_base. */
+const char *const temp_file_path = "output.OBJ";
+
+static std::string read_temp_file_in_string(const std::string &file_path)
+{
+  std::ifstream temp_stream(file_path);
+  std::ostringstream input_ss;
+  input_ss << temp_stream.rdbuf();
+  return input_ss.str();
+}
+
+TEST(obj_exporter_writer, header)
+{
+  /* Because testing doesn't fully initialize Blender, we need the following. */
+  BKE_tempdir_init(NULL);
+  std::string out_file_path = blender::tests::flags_test_release_dir() + "/" + temp_file_path;
+  {
+    OBJExportParamsDefault _export;
+    std::unique_ptr<OBJWriter> writer = init_writer(_export.params, out_file_path);
+    if (!writer) {
+      ADD_FAILURE();
+      return;
+    }
+    writer->write_header();
+  }
+  const std::string result = read_temp_file_in_string(out_file_path);
+  using namespace std::string_literals;
+  ASSERT_EQ(result, "# Blender "s + BKE_blender_version_string() + "\n" + "# www.blender.org\n");
+  BLI_delete(out_file_path.c_str(), false, false);
+}
+
+TEST(obj_exporter_writer, mtllib)
+{
+  std::string out_file_path = blender::tests::flags_test_release_dir() + "/" + temp_file_path;
+  {
+    OBJExportParamsDefault _export;
+    std::unique_ptr<OBJWriter> writer = init_writer(_export.params, out_file_path);
+    if (!writer) {
+      ADD_FAILURE();
+      return;
+    }
+    writer->write_mtllib_name("/Users/blah.mtl");
+    writer->write_mtllib_name("\\C:\\blah.mtl");
+  }
+  const std::string result = read_temp_file_in_string(out_file_path);
+  ASSERT_EQ(result, "mtllib blah.mtl\nmtllib blah.mtl\n");
+}
+
+/* Return true if string #a and string #b are equal after their first newline. */
+static bool strings_equal_after_first_lines(const std::string &a, const std::string &b)
+{
+  /* If `dbg_level > 0` then a failing test will print context around the first mismatch. */
+  const bool dbg_level = 0;
+  const size_t a_len = a.size();
+  const size_t b_len = b.size();
+  const size_t a_next = a.find_first_of('\n');
+  const size_t b_next = b.find_first_of('\n');
+  if (a_next == std::string::npos || b_next == std::string::npos) {
+    if (dbg_level > 0) {
+      std::cout << "Couldn't find newline in one of args\n";
+    }
+    return false;
+  }
+  if (dbg_level > 0) {
+    if (a.compare(a_next, a_len - a_next, b, b_next, b_len - b_next) != 0) {
+      for (int i = 0; i < a_len - a_next && i < b_len - b_next; ++i) {
+        if (a[a_next + i] != b[b_next + i]) {
+          std::cout << "Difference found at pos " << a_next + i << " of a\n";
+          std::cout << "a: " << a.substr(a_next + i, 100) << " ...\n";
+          std::cout << "b: " << b.substr(b_next + i, 100) << " ... \n";
+          return false;
+        }
+      }
+    }
+    else {
+      return true;
+    }
+  }
+  return a.compare(a_next, a_len - a_next, b, b_next, b_len - b_next) == 0;
+}
+
+/* From here on, tests are whole file tests, testing for golden output. */
+class obj_exporter_regression_test : public obj_exporter_test {
+ public:
+  /**
+   * Export the given blend file with the given parameters and
+   * test to see if it matches a golden file (ignoring any difference in Blender version number).
+   * \param blendfile: input, relative to "tests" directory.
+   * \param golden_obj: expected output, relative to "tests" directory.
+   * \param params: the parameters to be used for export.
+   */
+  void compare_obj_export_to_golden(const std::string &blendfile,
+                                    const std::string &golden_obj,
+                                    const std::string &golden_mtl,
+                                    OBJExportParams &params)
+  {
+    if (!load_file_and_depsgraph(blendfile)) {
+      return;
+    }
+    /* Because testing doesn't fully initialize Blender, we need the following. */
+    BKE_tempdir_init(NULL);
+    std::string tempdir = std::string(BKE_tempdir_base());
+    std::string out_file_path = tempdir + BLI_path_basename(golden_obj.c_str());
+    strncpy(params.filepath, out_file_path.c_str(), FILE_MAX);
+    params.blen_filepath = blendfile.c_str();
+    export_frame(depsgraph, params, out_file_path.c_str());
+    std::string output_str = read_temp_file_in_string(out_file_path);
+
+    std::string golden_file_path = blender::tests::flags_test_asset_dir() + "/" + golden_obj;
+    std::string golden_str = read_temp_file_in_string(golden_file_path);
+    ASSERT_TRUE(strings_equal_after_first_lines(output_str, golden_str));
+    BLI_delete(out_file_path.c_str(), false, false);
+    if (!golden_mtl.empty()) {
+      std::string out_mtl_file_path = tempdir + BLI_path_basename(golden_mtl.c_str());
+      std::string output_mtl_str = read_temp_file_in_string(out_mtl_file_path);
+      std::string golden_mtl_file_path = blender::tests::flags_test_asset_dir() + "/" + golden_mtl;
+      std::string golden_mtl_str = read_temp_file_in_string(golden_mtl_file_path);
+      ASSERT_TRUE(strings_equal_after_first_lines(output_mtl_str, golden_mtl_str));
+      BLI_delete(out_mtl_file_path.c_str(), false, false);
+    }
+  }
+};
+
+TEST_F(obj_exporter_regression_test, all_tris)
+{
+  OBJExportParamsDefault _export;
+  compare_obj_export_to_golden("io_tests/blend_geometry/all_tris.blend",
+                               "io_tests/obj/all_tris.obj",
+                               "io_tests/obj/all_tris.mtl",
+                               _export.params);
+}
+
+TEST_F(obj_exporter_regression_test, all_quads)
+{
+  OBJExportParamsDefault _export;
+  _export.params.scaling_factor = 2.0f;
+  _export.params.export_materials = false;
+  compare_obj_export_to_golden(
+      "io_tests/blend_geometry/all_quads.blend", "io_tests/obj/all_quads.obj", "", _export.params);
+}
+
+TEST_F(obj_exporter_regression_test, fgons)
+{
+  OBJExportParamsDefault _export;
+  _export.params.forward_axis = OBJ_AXIS_Y_FORWARD;
+  _export.params.up_axis = OBJ_AXIS_Z_UP;
+  _export.params.export_materials = false;
+  compare_obj_export_to_golden(
+      "io_tests/blend_geometry/fgons.blend", "io_tests/obj/fgons.obj", "", _export.params);
+}
+
+TEST_F(obj_exporter_regression_test, edges)
+{
+  OBJExportParamsDefault _export;
+  _export.params.forward_axis = OBJ_AXIS_Y_FORWARD;
+  _export.params.up_axis = OBJ_AXIS_Z_UP;
+  _export.params.export_materials = false;
+  compare_obj_export_to_golden(
+      "io_tests/blend_geometry/edges.blend", "io_tests/obj/edges.obj", "", _export.params);
+}
+
+TEST_F(obj_exporter_regression_test, vertices)
+{
+  OBJExportParamsDefault _export;
+  _export.params.forward_axis = OBJ_AXIS_Y_FORWARD;
+  _export.params.up_axis = OBJ_AXIS_Z_UP;
+  _export.params.export_materials = false;
+  compare_obj_export_to_golden(
+      "io_tests/blend_geometry/vertices.blend", "io_tests/obj/vertices.obj", "", _export.params);
+}
+
+TEST_F(obj_exporter_regression_test, nurbs_as_nurbs)
+{
+  OBJExportParamsDefault _export;
+  _export.params.forward_axis = OBJ_AXIS_Y_FORWARD;
+  _export.params.up_axis = OBJ_AXIS_Z_UP;
+  _export.params.export_materials = false;
+  _export.params.export_curves_as_nurbs = true;
+  compare_obj_export_to_golden(
+      "io_tests/blend_geometry/nurbs.blend", "io_tests/obj/nurbs.obj", "", _export.params);
+}
+
+TEST_F(obj_exporter_regression_test, nurbs_as_mesh)
+{
+  OBJExportParamsDefault _export;
+  _export.params.forward_axis = OBJ_AXIS_Y_FORWARD;
+  _export.params.up_axis = OBJ_AXIS_Z_UP;
+  _export.params.export_materials = false;
+  _export.params.export_curves_as_nurbs = false;
+  compare_obj_export_to_golden(
+      "io_tests/blend_geometry/nurbs.blend", "io_tests/obj/nurbs_mesh.obj", "", _export.params);
+}
+
+TEST_F(obj_exporter_regression_test, cube_all_data_triangulated)
+{
+  OBJExportParamsDefault _export;
+  _export.params.forward_axis = OBJ_AXIS_Y_FORWARD;
+  _export.params.up_axis = OBJ_AXIS_Z_UP;
+  _export.params.export_materials = false;
+  _export.params.export_triangulated_mesh = true;
+  compare_obj_export_to_golden("io_tests/blend_geometry/cube_all_data.blend",
+                               "io_tests/obj/cube_all_data_triangulated.obj",
+                               "",
+                               _export.params);
+}
+
+TEST_F(obj_exporter_regression_test, suzanne_all_data)
+{
+  OBJExportParamsDefault _export;
+  _export.params.forward_axis = OBJ_AXIS_Y_FORWARD;
+  _export.params.up_axis = OBJ_AXIS_Z_UP;
+  _export.params.export_materials = false;
+  _export.params.export_smooth_groups = true;
+  compare_obj_export_to_golden("io_tests/blend_geometry/suzanne_all_data.blend",
+                               "io_tests/obj/suzanne_all_data.obj",
+                               "",
+                               _export.params);
+}
+
+TEST_F(obj_exporter_regression_test, all_objects)
+{
+  OBJExportParamsDefault _export;
+  _export.params.forward_axis = OBJ_AXIS_Y_FORWARD;
+  _export.params.up_axis = OBJ_AXIS_Z_UP;
+  _export.params.export_smooth_groups = true;
+  compare_obj_export_to_golden("io_tests/blend_scene/all_objects.blend",
+                               "io_tests/obj/all_objects.obj",
+                               "io_tests/obj/all_objects.mtl",
+                               _export.params);
+}
+
+}  // namespace blender::io::obj