- Particle-particle effectors we're quite unstable and not accurate at all. Now this should be fixed (especially with other integrators than euler) as the needed inter-frame effector particle positions are interpolated properly from the current and previous positions (previously only the most recent position was used).

- In practice this removes the dependency of particle simulations from the update order of objects and different particle systems inside objects.
- As a nice side effect out of this we also get fully correct birth positions for "near reactor particles" (previously for example smoke trail reactor particles were not born smoothly along the target particles path).

1 files changed, 2 insertions, 0 deletions

diff --git a/source/blender/makesdna/DNA_particle_types.h b/source/blender/makesdna/DNA_particle_types.h
index 8618bee3638..7dd69b2151c 100644
--- a/source/blender/makesdna/DNA_particle_types.h
+++ b/source/blender/makesdna/DNA_particle_types.h
@@ -66,6 +66,8 @@ typedef struct ParticleData {
 	ParticleKey state;		/* normally current global coordinates or	*/
 							/* in sticky object space if dead & sticky	*/
 
+	ParticleKey prev_state; /* previous state */
+
 	HairKey *hair;			/* hair vertices */
 
 	ParticleKey *keys;		/* keyed states */