I have a particle system with instanced wasps that is 'swarming' around an attractor. Both the attractor and the particle object itself are being translated through a scene from one side to the next. My problem has to do with the instance's aim direction. Normally I would just choose "velocity" as the aim direction and all the particles would point where they are heading. However in this case, because the actual particle object is moving, "velocity" doesn't work as it is relative to the particle objects position. So I have to set the aim direction to "World Velocity". This look great until I cache! Once the nParticles are cached, the instances no longer use the world velocity and are not aiming where they are moving to in world space.
Any thoughts on this problem?