Fix T50745: Shape key editing on bezier objects broken with Rendered Viewport Shading

So... Curve+shapekey was even more broken than it looked, this report was
actually a nice crasher (immediate crash in an ASAN build when trying to
edit a curve shapekey with some viewport rendering enabled).

There were actually two different issues here.

I) The less critical: rB6f1493f68fe was not fully fixing issues from
T50614. More specifically, if you updated obdata from editnurb
*without* freeing editnurb afterwards, you had a 'restored' (to
original curve) editnurb, without the edited shapekey modifications
anymore. This was fixed by tweaking again `calc_shapeKeys()` behavior in
`ED_curve_editnurb_load()`.

II) The crasher: in `ED_curve_editnurb_make()`, the call to
`init_editNurb_keyIndex()` was directly storing pointers of obdata
nurbs. Since those get freed every time `ED_curve_editnurb_load()` is
executed, it easily ended up being pointers to freed memory. This was
fixed by copying those data, which implied more complex handling code
for editnurbs->keyindex, and some reshuffling of a few functions to
avoid duplicating things between editor's editcurve.c and BKE's curve.c

Note that the separation of functions between editors and BKE area for
curve could use a serious update, it's currently messy to say the least.
Then again, that area is due to rework since a long time now... :/

Finally, aligned 'for_render' curve evaluation to mesh one - now
editing a shapekey will show in rendered viewports, if it does have some
weight (exactly as with shapekeys of meshes).

1 files changed, 1 insertions, 1 deletions

diff --git a/source/blender/blenkernel/intern/displist.c b/source/blender/blenkernel/intern/displist.c
index 49db75a0474..f8a9d57f579 100644
--- a/source/blender/blenkernel/intern/displist.c
+++ b/source/blender/blenkernel/intern/displist.c
@@ -819,7 +819,7 @@ static void curve_calc_modifiers_pre(Scene *scene, Object *ob, ListBase *nurb,
 	if (editmode)
 		required_mode |= eModifierMode_Editmode;
 
-	if (cu->editnurb == NULL) {
+	if (!editmode) {
 		keyVerts = BKE_key_evaluate_object(ob, &numVerts);
 
 		if (keyVerts) {