NLA: insert keyframes correctly for strips with non-Replace mode.

NLA strips support using the keyframe values in a variety of ways:
adding, subtracting, multiplying, linearly mixing with the result
of strips located below in the stack. This is intended for layering
tweaks on top of a base animation.

However, when inserting keyframes into such strips, it simply inserts
the final value of the property, irrespective of these settings. This
in fact makes the feature nearly useless.

To fix this it is necessary to evaluate the NLA stack below the
edited strip and correctly compute the raw key that would produce
the intended final value, according to the mode and influence.

Differential Revision: https://developer.blender.org/D3927

1 files changed, 4 insertions, 2 deletions

diff --git a/source/blender/editors/include/ED_keyframing.h b/source/blender/editors/include/ED_keyframing.h
index b42fdf456e0..aba381f7989 100644
--- a/source/blender/editors/include/ED_keyframing.h
+++ b/source/blender/editors/include/ED_keyframing.h
@@ -56,6 +56,8 @@ struct PointerRNA;
 struct PropertyRNA;
 struct EnumPropertyItem;
 
+struct NlaKeyframingContext;
+
 #include "DNA_anim_types.h"
 #include "RNA_types.h"
 
@@ -109,7 +111,7 @@ int insert_vert_fcurve(struct FCurve *fcu, float x, float y, eBezTriple_Keyframe
  * Use this to insert a keyframe using the current value being keyframed, in the
  * nominated F-Curve (no creation of animation data performed). Returns success.
  */
-bool insert_keyframe_direct(struct Depsgraph *depsgraph, struct ReportList *reports, struct PointerRNA ptr, struct PropertyRNA *prop, struct FCurve *fcu, float cfra, eBezTriple_KeyframeType keytype, eInsertKeyFlags flag);
+bool insert_keyframe_direct(struct Depsgraph *depsgraph, struct ReportList *reports, struct PointerRNA ptr, struct PropertyRNA *prop, struct FCurve *fcu, float cfra, eBezTriple_KeyframeType keytype, struct NlaKeyframingContext *nla, eInsertKeyFlags flag);
 
 /* -------- */
 
@@ -119,7 +121,7 @@ bool insert_keyframe_direct(struct Depsgraph *depsgraph, struct ReportList *repo
  */
 short insert_keyframe(
         struct Main *bmain, struct Depsgraph *depsgraph, struct ReportList *reports, struct ID *id, struct bAction *act,
-        const char group[], const char rna_path[], int array_index, float cfra, eBezTriple_KeyframeType keytype, eInsertKeyFlags flag);
+        const char group[], const char rna_path[], int array_index, float cfra, eBezTriple_KeyframeType keytype, struct ListBase *nla_cache, eInsertKeyFlags flag);
 
 /* Main Keyframing API call:
  *  Use this to delete keyframe on current frame for relevant channel. Will perform checks just in case.