NLA SoC: Bugfix for Deleting Keyframes

When an F-Curve doesn't contain any keyframes anymore but it still exists, the F-Curve's value is not recalculated and flushed anymore if the F-Curve's value will not change. That is, if the F-Curve doesn't have any other data, i.e. drivers or generator-modifiers, which would still change its value, it wouldn't be recalculated to have a value of zero. 

This solves the problem of deleting all scale keyframes, whereby objects/bones would appear to 'vanish'

2 files changed, 10 insertions, 4 deletions

diff --git a/source/blender/blenkernel/BKE_fcurve.h b/source/blender/blenkernel/BKE_fcurve.h
index af272e892f2..5c77e3c2ae4 100644
--- a/source/blender/blenkernel/BKE_fcurve.h
+++ b/source/blender/blenkernel/BKE_fcurve.h
@@ -112,7 +112,7 @@ void fcurve_free_modifiers(struct FCurve *fcu);
 struct FModifier *fcurve_find_active_modifier(struct FCurve *fcu);
 void fcurve_set_active_modifier(struct FCurve *fcu, struct FModifier *fcm);
 
-short fcurve_has_suitable_modifier(FCurve *fcu, int mtype, short acttype);
+short fcurve_has_suitable_modifier(struct FCurve *fcu, int mtype, short acttype);
 
 float evaluate_time_fmodifiers(ListBase *modifiers, struct FCurve *fcu, float cvalue, float evaltime);
 void evaluate_value_fmodifiers(ListBase *modifiers, struct FCurve *fcu, float *cvalue, float evaltime);
diff --git a/source/blender/blenkernel/intern/fcurve.c b/source/blender/blenkernel/intern/fcurve.c
index d8b5135a1b1..856930e5a44 100644
--- a/source/blender/blenkernel/intern/fcurve.c
+++ b/source/blender/blenkernel/intern/fcurve.c
@@ -2415,10 +2415,16 @@ float evaluate_fcurve (FCurve *fcu, float evaltime)
 }
 
 /* Calculate the value of the given F-Curve at the given frame, and set its curval */
-// TODO: will this be necessary?
 void calculate_fcurve (FCurve *fcu, float ctime)
 {
-	/* calculate and set curval (evaluates driver too) */
-	fcu->curval= evaluate_fcurve(fcu, ctime);
+	/* only calculate + set curval (overriding the existing value) if curve has 
+	 * any data which warrants this...
+	 */
+	if ( (fcu->totvert) || (fcu->driver && !(fcu->driver->flag & DRIVER_FLAG_INVALID)) ||
+		 fcurve_has_suitable_modifier(fcu, 0, FMI_TYPE_GENERATE_CURVE) )
+	{
+		/* calculate and set curval (evaluates driver too if necessary) */
+		fcu->curval= evaluate_fcurve(fcu, ctime);
+	}
 }