Merge branch 'blender-v3.1-release'

Also fixed conflicts due to the change in file writing in the new obj exporter
in master, and fixed one of the tests that was added in master but not 3.1.

5 files changed, 41 insertions, 4 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 4f5321019d5..13d1a4fdde6 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
@@ -369,11 +369,25 @@ void OBJWriter::write_nurbs_curve(FormatHandler<eFileType::OBJ> &fh,
 
     /**
      * In `parm u 0 0.1 ..` line:, (total control points + 2) equidistant numbers in the
-     * parameter range are inserted.
+     * parameter range are inserted. However for curves with endpoint flag,
+     * first degree+1 numbers are zeroes, and last degree+1 numbers are ones
      */
+
+    const short flagsu = obj_nurbs_data.get_nurbs_flagu(spline_idx);
+    const bool cyclic = flagsu & CU_NURB_CYCLIC;
+    const bool endpoint = !cyclic && (flagsu & CU_NURB_ENDPOINT);
     fh.write<eOBJSyntaxElement::nurbs_parameter_begin>();
     for (int i = 1; i <= total_control_points + 2; i++) {
-      fh.write<eOBJSyntaxElement::nurbs_parameters>(1.0f * i / (total_control_points + 2 + 1));
+      float parm = 1.0f * i / (total_control_points + 2 + 1);
+      if (endpoint) {
+        if (i <= nurbs_degree) {
+          parm = 0;
+        }
+        else if (i > total_control_points + 2 - nurbs_degree) {
+          parm = 1;
+        }
+      }
+      fh.write<eOBJSyntaxElement::nurbs_parameters>(parm);
     }
     fh.write<eOBJSyntaxElement::nurbs_parameter_end>();
 
diff --git a/source/blender/io/wavefront_obj/exporter/obj_export_io.hh b/source/blender/io/wavefront_obj/exporter/obj_export_io.hh
index 692eb7f5db5..e5b731aa51d 100644
--- a/source/blender/io/wavefront_obj/exporter/obj_export_io.hh
+++ b/source/blender/io/wavefront_obj/exporter/obj_export_io.hh
@@ -177,7 +177,7 @@ constexpr FormattingSyntax syntax_elem_to_formatting(const eOBJSyntaxElement key
       return {"curv 0.0 1.0", 0, is_type_string_related<T...>};
     }
     case eOBJSyntaxElement::nurbs_parameter_begin: {
-      return {"parm 0.0", 0, is_type_string_related<T...>};
+      return {"parm u 0.0", 0, is_type_string_related<T...>};
     }
     case eOBJSyntaxElement::nurbs_parameters: {
       return {" %f", 1, is_type_float<T...>};
diff --git a/source/blender/io/wavefront_obj/exporter/obj_export_nurbs.cc b/source/blender/io/wavefront_obj/exporter/obj_export_nurbs.cc
index ec690115115..8a6d3b4b93a 100644
--- a/source/blender/io/wavefront_obj/exporter/obj_export_nurbs.cc
+++ b/source/blender/io/wavefront_obj/exporter/obj_export_nurbs.cc
@@ -102,4 +102,10 @@ int OBJCurve::get_nurbs_degree(const int spline_index) const
   return nurb->orderu - 1;
 }
 
+short OBJCurve::get_nurbs_flagu(const int spline_index) const
+{
+  const Nurb *const nurb = static_cast<Nurb *>(BLI_findlink(&export_curve_->nurb, spline_index));
+  return nurb->flagu;
+}
+
 }  // namespace blender::io::obj
diff --git a/source/blender/io/wavefront_obj/exporter/obj_export_nurbs.hh b/source/blender/io/wavefront_obj/exporter/obj_export_nurbs.hh
index 0c71c3cc09d..d831afec0a0 100644
--- a/source/blender/io/wavefront_obj/exporter/obj_export_nurbs.hh
+++ b/source/blender/io/wavefront_obj/exporter/obj_export_nurbs.hh
@@ -61,6 +61,10 @@ class OBJCurve : NonCopyable {
    * Get the degree of the NURBS spline at the given index.
    */
   int get_nurbs_degree(int spline_index) const;
+  /**
+   * Get the U flags (CU_NURB_*) of the NURBS spline at the given index.
+   */
+  short get_nurbs_flagu(int spline_index) const;
 
  private:
   /**
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 ac2ee8d566b..01f201897cf 100644
--- a/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
+++ b/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
@@ -265,7 +265,7 @@ o abcdef
 o 012345678901234567890123456789abcd
 o 123
 curv 0.0 1.0
-parm 0.0
+parm u 0.0
 )";
   ASSERT_EQ(got_string, expected);
 }
@@ -410,6 +410,19 @@ TEST_F(obj_exporter_regression_test, nurbs_as_nurbs)
       "io_tests/blend_geometry/nurbs.blend", "io_tests/obj/nurbs.obj", "", _export.params);
 }
 
+TEST_F(obj_exporter_regression_test, nurbs_curves_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_curves.blend",
+                               "io_tests/obj/nurbs_curves.obj",
+                               "",
+                               _export.params);
+}
+
 TEST_F(obj_exporter_regression_test, nurbs_as_mesh)
 {
   OBJExportParamsDefault _export;