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, 15 insertions, 9 deletions

diff --git a/source/blender/blenkernel/intern/displist.c b/source/blender/blenkernel/intern/displist.c
index 1fcc1b1bcef..c860e57520d 100644
--- a/source/blender/blenkernel/intern/displist.c
+++ b/source/blender/blenkernel/intern/displist.c
@@ -770,8 +770,12 @@ static ModifierData *curve_get_tessellate_point(Scene *scene,
 }
 
 /* Return true if any modifier was applied. */
-static bool curve_calc_modifiers_pre(
-    Depsgraph *depsgraph, Scene *scene, Object *ob, ListBase *nurb, const bool for_render)
+bool BKE_curve_calc_modifiers_pre(Depsgraph *depsgraph,
+                                  Scene *scene,
+                                  Object *ob,
+                                  ListBase *source_nurb,
+                                  ListBase *target_nurb,
+                                  const bool for_render)
 {
   VirtualModifierData virtualModifierData;
   ModifierData *md = BKE_modifiers_get_virtual_modifierlist(ob, &virtualModifierData);
@@ -810,13 +814,13 @@ static bool curve_calc_modifiers_pre(
     keyVerts = BKE_key_evaluate_object(ob, &numElems);
 
     if (keyVerts) {
-      BLI_assert(BKE_keyblock_curve_element_count(nurb) == numElems);
+      BLI_assert(BKE_keyblock_curve_element_count(source_nurb) == numElems);
 
       /* split coords from key data, the latter also includes
        * tilts, which is passed through in the modifier stack.
        * this is also the reason curves do not use a virtual
        * shape key modifier yet. */
-      deformedVerts = BKE_curve_nurbs_key_vert_coords_alloc(nurb, keyVerts, &numVerts);
+      deformedVerts = BKE_curve_nurbs_key_vert_coords_alloc(source_nurb, keyVerts, &numVerts);
     }
   }
 
@@ -832,7 +836,7 @@ static bool curve_calc_modifiers_pre(
       }
 
       if (!deformedVerts) {
-        deformedVerts = BKE_curve_nurbs_vert_coords_alloc(nurb, &numVerts);
+        deformedVerts = BKE_curve_nurbs_vert_coords_alloc(source_nurb, &numVerts);
       }
 
       mti->deformVerts(md, &mectx, NULL, deformedVerts, numVerts);
@@ -845,11 +849,11 @@ static bool curve_calc_modifiers_pre(
   }
 
   if (deformedVerts) {
-    BKE_curve_nurbs_vert_coords_apply(nurb, deformedVerts, false);
+    BKE_curve_nurbs_vert_coords_apply(target_nurb, deformedVerts, false);
     MEM_freeN(deformedVerts);
   }
   if (keyVerts) { /* these are not passed through modifier stack */
-    BKE_curve_nurbs_key_vert_tilts_apply(nurb, keyVerts);
+    BKE_curve_nurbs_key_vert_tilts_apply(target_nurb, keyVerts);
   }
 
   if (keyVerts) {
@@ -1151,7 +1155,8 @@ void BKE_displist_make_surf(Depsgraph *depsgraph,
   }
 
   if (!for_orco) {
-    force_mesh_conversion = curve_calc_modifiers_pre(depsgraph, scene, ob, &nubase, for_render);
+    force_mesh_conversion = BKE_curve_calc_modifiers_pre(
+        depsgraph, scene, ob, &nubase, &nubase, for_render);
   }
 
   LISTBASE_FOREACH (Nurb *, nu, &nubase) {
@@ -1501,7 +1506,8 @@ static void do_makeDispListCurveTypes(Depsgraph *depsgraph,
     }
 
     if (!for_orco) {
-      force_mesh_conversion = curve_calc_modifiers_pre(depsgraph, scene, ob, &nubase, for_render);
+      force_mesh_conversion = BKE_curve_calc_modifiers_pre(
+          depsgraph, scene, ob, &nubase, &nubase, for_render);
     }
 
     BKE_curve_bevelList_make(ob, &nubase, for_render);