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, 1 deletions

diff --git a/source/blender/editors/animation/keyingsets.c b/source/blender/editors/animation/keyingsets.c
index 1fe8a34d166..d980e4322dd 100644
--- a/source/blender/editors/animation/keyingsets.c
+++ b/source/blender/editors/animation/keyingsets.c
@@ -962,6 +962,7 @@ int ANIM_apply_keyingset(bContext *C, ListBase *dsources, bAction *act, KeyingSe
 	Scene *scene = CTX_data_scene(C);
 	ReportList *reports = CTX_wm_reports(C);
 	KS_Path *ksp;
+	ListBase nla_cache = {NULL, NULL};
 	const short base_kflags = ANIM_get_keyframing_flags(scene, 1);
 	const char *groupname = NULL;
 	short kflag = 0, success = 0;
@@ -1039,7 +1040,7 @@ int ANIM_apply_keyingset(bContext *C, ListBase *dsources, bAction *act, KeyingSe
 		for (; i < arraylen; i++) {
 			/* action to take depends on mode */
 			if (mode == MODIFYKEY_MODE_INSERT)
-				success += insert_keyframe(bmain, depsgraph, reports, ksp->id, act, groupname, ksp->rna_path, i, cfra, keytype, kflag2);
+				success += insert_keyframe(bmain, depsgraph, reports, ksp->id, act, groupname, ksp->rna_path, i, cfra, keytype, &nla_cache, kflag2);
 			else if (mode == MODIFYKEY_MODE_DELETE)
 				success += delete_keyframe(bmain, reports, ksp->id, act, groupname, ksp->rna_path, i, cfra, kflag2);
 		}
@@ -1063,6 +1064,8 @@ int ANIM_apply_keyingset(bContext *C, ListBase *dsources, bAction *act, KeyingSe
 		WM_main_add_notifier(NC_ANIMATION | ND_KEYFRAME | NA_ADDED, NULL);
 	}
 
+	BKE_animsys_free_nla_keyframing_context_cache(&nla_cache);
+
 	/* return the number of channels successfully affected */
 	return success;
 }