Prevent copying too much in the Rigid Body simulation

To prevent the pointcache from being copied-on-write too (and requiring
copying back), the cache is now shared between the original and
evaluated scenes. Reading from the cache is always allowed; running the
sim and writing to the cache is only allowed when the depsgraph is
active.

Some pointers have moved from RigidBodyWorld (RBO) to
RigidBodyWorldShared (RBOS). writefile.c copies some pointers back from
RBOS to RBO so that the file can still be opened on older Blenders
without crashing on a segfault.

The RigidBodyWorldShared struct is written to the blend file, because it
refers to the PointCache ID block.

The RigidObjectShared struct is runtime-only, and thus not saved to the
blend file.

An RNA getter-function is used to hide the new 'shared' pointer. As a
result the Python API hasn't changed.

Reviewed by: campbellbarton

Differential Revision: https://developer.blender.org/D3508

1 files changed, 27 insertions, 10 deletions

diff --git a/source/blender/makesdna/DNA_rigidbody_types.h b/source/blender/makesdna/DNA_rigidbody_types.h
index 5a7e7c92380..b7d422e7bdf 100644
--- a/source/blender/makesdna/DNA_rigidbody_types.h
+++ b/source/blender/makesdna/DNA_rigidbody_types.h
@@ -42,6 +42,16 @@ struct EffectorWeights;
 /* ******************************** */
 /* RigidBody World */
 
+/* Container for data shared by original and evaluated copies of RigidBodyWorld */
+typedef struct RigidBodyWorld_Shared {
+	/* cache */
+	struct PointCache *pointcache;
+	struct ListBase ptcaches;
+
+	/* References to Physics Sim objects. Exist at runtime only ---------------------- */
+	void *physics_world;		/* Physics sim world (i.e. btDiscreteDynamicsWorld) */
+} RigidBodyWorld_Shared;
+
 /* RigidBodyWorld (rbw)
  *
  * Represents a "simulation scene" existing within the parent scene.
@@ -58,9 +68,9 @@ typedef struct RigidBodyWorld {
 	int pad;
 	float ltime;				/* last frame world was evaluated for (internal) */
 
-	/* cache */
-	struct PointCache *pointcache;
-	struct ListBase ptcaches;
+	struct RigidBodyWorld_Shared *shared; /* This pointer is shared between all evaluated copies */
+	struct PointCache *pointcache DNA_DEPRECATED; /* Moved to shared->pointcache */
+	struct ListBase ptcaches DNA_DEPRECATED; /* Moved to shared->ptcaches */
 	int numbodies;              /* number of objects in rigid body group */
 
 	short steps_per_second;		/* number of simulation steps thaken per second */
@@ -68,9 +78,6 @@ typedef struct RigidBodyWorld {
 
 	int flag;					/* (eRigidBodyWorld_Flag) settings for this RigidBodyWorld */
 	float time_scale;			/* used to speed up or slow down the simulation */
-
-	/* References to Physics Sim objects. Exist at runtime only ---------------------- */
-	void *physics_world;		/* Physics sim world (i.e. btDiscreteDynamicsWorld) */
 } RigidBodyWorld;
 
 /* Flags for RigidBodyWorld */
@@ -86,6 +93,18 @@ typedef enum eRigidBodyWorld_Flag {
 /* ******************************** */
 /* RigidBody Object */
 
+/* Container for data that is shared among CoW copies.
+ *
+ * This is placed in a separate struct so that, for example, the physics_shape
+ * pointer can be replaced without having to update all CoW copies. */
+#
+#
+typedef struct RigidBodyOb_Shared {
+	/* References to Physics Sim objects. Exist at runtime only */
+	void *physics_object;	/* Physics object representation (i.e. btRigidBody) */
+	void *physics_shape;	/* Collision shape used by physics sim (i.e. btCollisionShape) */
+} RigidBodyOb_Shared;
+
 /* RigidBodyObject (rbo)
  *
  * Represents an object participating in a RigidBody sim.
@@ -93,10 +112,6 @@ typedef enum eRigidBodyWorld_Flag {
  * participating in a sim.
  */
 typedef struct RigidBodyOb {
-	/* References to Physics Sim objects. Exist at runtime only */
-	void *physics_object;	/* Physics object representation (i.e. btRigidBody) */
-	void *physics_shape;	/* Collision shape used by physics sim (i.e. btCollisionShape) */
-
 	/* General Settings for this RigidBodyOb */
 	short type;				/* (eRigidBodyOb_Type) role of RigidBody in sim  */
 	short shape;			/* (eRigidBody_Shape) collision shape to use */
@@ -123,6 +138,8 @@ typedef struct RigidBodyOb {
 	float orn[4];			/* rigid body orientation */
 	float pos[3];			/* rigid body position */
 	float pad1;
+
+	struct RigidBodyOb_Shared *shared; /* This pointer is shared between all evaluated copies */
 } RigidBodyOb;