Fix crash happening in Cycles fcurve modifier

Summary:
Crash was happening because of fcurve modifier stack
used modifier's DNA to store temporary data.

Now made it so storage for such a thing is being
allocated locally per object update so multiple objects
which shares the same animation wouldn't run into
threading conflict anymore.

This storage might be a part of EvaluationContext,
but that'd mean passing this context all over in
object_where_is which will clutter API for now without
actual benefit for this.

Optimization notes: storage is only being allocated
if there're Cycles modifier in the stack, so there're
no extra allocations happening in all other cases.

To make code a bit less cluttered with this storage
passing all over the place added extra callbacks to
the FModifier storage which runs evaluation with the
given storage.

Reviewers: brecht, campbellbarton, aligorith

CC: plasmasolutions

Differential Revision: https://developer.blender.org/D147

1 files changed, 8 insertions, 4 deletions

diff --git a/source/blender/blenkernel/intern/fcurve.c b/source/blender/blenkernel/intern/fcurve.c
index 32098c67ca7..04765a74b77 100644
--- a/source/blender/blenkernel/intern/fcurve.c
+++ b/source/blender/blenkernel/intern/fcurve.c
@@ -2138,6 +2138,7 @@ static float fcurve_eval_samples(FCurve *fcu, FPoint *fpts, float evaltime)
  */
 float evaluate_fcurve(FCurve *fcu, float evaltime)
 {
+	FModifierStackStorage *storage;
 	float cvalue = 0.0f;
 	float devaltime;
 	
@@ -2177,9 +2178,10 @@ float evaluate_fcurve(FCurve *fcu, float evaltime)
 			}
 		}
 	}
-	
+
 	/* evaluate modifiers which modify time to evaluate the base curve at */
-	devaltime = evaluate_time_fmodifiers(&fcu->modifiers, fcu, cvalue, evaltime);
+	storage = evaluate_fmodifiers_storage_new(&fcu->modifiers);
+	devaltime = evaluate_time_fmodifiers(storage, &fcu->modifiers, fcu, cvalue, evaltime);
 	
 	/* evaluate curve-data 
 	 *	- 'devaltime' instead of 'evaltime', as this is the time that the last time-modifying 
@@ -2191,8 +2193,10 @@ float evaluate_fcurve(FCurve *fcu, float evaltime)
 		cvalue = fcurve_eval_samples(fcu, fcu->fpt, devaltime);
 	
 	/* evaluate modifiers */
-	evaluate_value_fmodifiers(&fcu->modifiers, fcu, &cvalue, evaltime);
-	
+	evaluate_value_fmodifiers(storage, &fcu->modifiers, fcu, &cvalue, evaltime);
+
+	evaluate_fmodifiers_storage_free(storage);
+
 	/* if curve can only have integral values, perform truncation (i.e. drop the decimal part)
 	 * here so that the curve can be sampled correctly
 	 */