[Bf-blender-cvs] [fb21201d424] blender-v2.93-release: Fix T94837: curve tilt on a 2-point-curve is wrong

[Philipp Oeser]

Commit: fb21201d4244e3bd8f9c01fece2cb14e0ae29d2d
Author: Philipp Oeser
Date:   Wed Jan 12 12:03:26 2022 +0100
Branches: blender-v2.93-release
https://developer.blender.org/rBfb21201d4244e3bd8f9c01fece2cb14e0ae29d2d

Fix T94837: curve tilt on a 2-point-curve is wrong

2-point-curves are treated separately from 3plus-point-curves (assume a
lot of the twisting reduction can be skipped, so there is a dedicated
function for single segment curves).

And while using the 3plus-point-curves function [`make_bevel_list_3D`]
would actually work in this case, the dedicated function
`make_bevel_list_segment_3D` would only consider the tilt of the second
point and would just copy over the quat to the first point as well. Dont
see a reason for this, now consider the first point's tilt as well.

Maniphest Tasks: T94837

Differential Revision: https://developer.blender.org/D13813

===================================================================

M	source/blender/blenkernel/intern/curve.c

===================================================================

diff --git a/source/blender/blenkernel/intern/curve.c b/source/blender/blenkernel/intern/curve.c
index 577e6758459..37cd62c3bc8 100644
--- a/source/blender/blenkernel/intern/curve.c
+++ b/source/blender/blenkernel/intern/curve.c
@@ -2524,12 +2524,15 @@ static void make_bevel_list_segment_3D(BevList *bl)
   normalize_v3(bevp1->dir);
 
   vec_to_quat(bevp1->quat, bevp1->dir, 5, 1);
-
   axis_angle_to_quat(q, bevp1->dir, bevp1->tilt);
   mul_qt_qtqt(bevp1->quat, q, bevp1->quat);
   normalize_qt(bevp1->quat);
+
   copy_v3_v3(bevp2->dir, bevp1->dir);
-  copy_qt_qt(bevp2->quat, bevp1->quat);
+  vec_to_quat(bevp2->quat, bevp2->dir, 5, 1);
+  axis_angle_to_quat(q, bevp2->dir, bevp2->tilt);
+  mul_qt_qtqt(bevp2->quat, q, bevp2->quat);
+  normalize_qt(bevp2->quat);
 }
 
 /* only for 2 points */