Python: Add to_curve method to the object API

This patch adds a to_curve method to the Object ID. This method is
analogous to the to_mesh method. The method can operate on curve and
text objects. For text objects, the text is converted into a 3D Curve ID
and that curve is returned. For curve objects, if apply_modifiers is
true, the spline deform modifiers will be applied and a Curve ID with
the result will be returned, otherwise a copy of the curve will be
returned.

The goal of this addition is to allow the developer to access the splines
of text objects and to get the result of modifier applications which was
otherwise not possible.

Reviewed By: Brecht

Differential Revision: https://developer.blender.org/D10354

1 files changed, 81 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/curve_convert.c b/source/blender/blenkernel/intern/curve_convert.c
new file mode 100644
index 00000000000..988ddb3bbc0
--- /dev/null
+++ b/source/blender/blenkernel/intern/curve_convert.c
@@ -0,0 +1,81 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+/** \file
+ * \ingroup bke
+ */
+
+#include "DNA_curve_types.h"
+#include "DNA_object_types.h"
+#include "DNA_vfont_types.h"
+
+#include "BLI_utildefines.h"
+
+#include "BKE_curve.h"
+#include "BKE_displist.h"
+#include "BKE_font.h"
+#include "BKE_lib_id.h"
+#include "BKE_modifier.h"
+
+#include "DEG_depsgraph.h"
+#include "DEG_depsgraph_query.h"
+
+static Curve *curve_from_font_object(Object *object, Depsgraph *depsgraph)
+{
+  Curve *curve = (Curve *)object->data;
+  Curve *new_curve = (Curve *)BKE_id_copy_ex(NULL, &curve->id, NULL, LIB_ID_COPY_LOCALIZE);
+
+  Object *evaluated_object = DEG_get_evaluated_object(depsgraph, object);
+  BKE_vfont_to_curve_nubase(evaluated_object, FO_EDIT, &new_curve->nurb);
+
+  new_curve->type = OB_CURVE;
+
+  new_curve->flag &= ~CU_3D;
+  BKE_curve_curve_dimension_update(new_curve);
+
+  return new_curve;
+}
+
+static Curve *curve_from_curve_object(Object *object, Depsgraph *depsgraph, bool apply_modifiers)
+{
+  Object *evaluated_object = DEG_get_evaluated_object(depsgraph, object);
+  Curve *curve = (Curve *)evaluated_object->data;
+  Curve *new_curve = (Curve *)BKE_id_copy_ex(NULL, &curve->id, NULL, LIB_ID_COPY_LOCALIZE);
+
+  if (apply_modifiers) {
+    BKE_curve_calc_modifiers_pre(depsgraph,
+                                 DEG_get_input_scene(depsgraph),
+                                 evaluated_object,
+                                 BKE_curve_nurbs_get(curve),
+                                 &new_curve->nurb,
+                                 DEG_get_mode(depsgraph) == DAG_EVAL_RENDER);
+  }
+
+  return new_curve;
+}
+
+Curve *BKE_curve_new_from_object(Object *object, Depsgraph *depsgraph, bool apply_modifiers)
+{
+  if (!ELEM(object->type, OB_FONT, OB_CURVE)) {
+    return NULL;
+  }
+
+  if (object->type == OB_FONT) {
+    return curve_from_font_object(object, depsgraph);
+  }
+
+  return curve_from_curve_object(object, depsgraph, apply_modifiers);
+}