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, 14 insertions, 3 deletions

diff --git a/source/blender/blenkernel/BKE_fcurve.h b/source/blender/blenkernel/BKE_fcurve.h
index c31dd745911..5ad378bc331 100644
--- a/source/blender/blenkernel/BKE_fcurve.h
+++ b/source/blender/blenkernel/BKE_fcurve.h
@@ -99,6 +99,8 @@ float driver_get_variable_value(struct ChannelDriver *driver, struct DriverVar *
 
 /* ************** F-Curve Modifiers *************** */
 
+typedef struct GHash FModifierStackStorage;
+
 /* F-Curve Modifier Type-Info (fmi):
  *  This struct provides function pointers for runtime, so that functions can be
  *  written more generally (with fewer/no special exceptions for various modifiers).
@@ -134,6 +136,10 @@ typedef struct FModifierTypeInfo {
 	float (*evaluate_modifier_time)(struct FCurve *fcu, struct FModifier *fcm, float cvalue, float evaltime);
 	/* evaluate the modifier for the given time and 'accumulated' value */
 	void (*evaluate_modifier)(struct FCurve *fcu, struct FModifier *fcm, float *cvalue, float evaltime);
+
+	/* Same as above but for modifiers which requires storage */
+	float (*evaluate_modifier_time_storage)(FModifierStackStorage *storage, struct FCurve *fcu, struct FModifier *fcm, float cvalue, float evaltime);
+	void (*evaluate_modifier_storage)(FModifierStackStorage *storage, struct FCurve *fcu, struct FModifier *fcm, float *cvalue, float evaltime);
 } FModifierTypeInfo;
 
 /* Values which describe the behavior of a FModifier Type */
@@ -157,7 +163,10 @@ typedef enum eFMI_Requirement_Flags {
 	 */
 	FMI_REQUIRES_NOTHING            = (1 << 1),
 	/* refer to modifier instance */
-	FMI_REQUIRES_RUNTIME_CHECK      = (1 << 2)
+	FMI_REQUIRES_RUNTIME_CHECK      = (1 << 2),
+
+	/* Requires to store data shared between time and valua evaluation */
+	FMI_REQUIRES_STORAGE            = (1 << 3)
 } eFMI_Requirement_Flags;
 
 /* Function Prototypes for FModifierTypeInfo's */
@@ -177,8 +186,10 @@ void set_active_fmodifier(ListBase *modifiers, struct FModifier *fcm);
 
 short list_has_suitable_fmodifier(ListBase *modifiers, 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);
+FModifierStackStorage *evaluate_fmodifiers_storage_new(ListBase *modifiers);
+void evaluate_fmodifiers_storage_free(FModifierStackStorage *storage);
+float evaluate_time_fmodifiers(FModifierStackStorage *storage, ListBase *modifiers, struct FCurve *fcu, float cvalue, float evaltime);
+void evaluate_value_fmodifiers(FModifierStackStorage *storage, ListBase *modifiers, struct FCurve *fcu, float *cvalue, float evaltime);
 
 void fcurve_bake_modifiers(struct FCurve *fcu, int start, int end);