# Moving particle system

I’m trying to add a smoke trail to my car, to simulate the effect of a locked wheel. When the car isn’t moving everything looks fine:

However, when the car moves the particles are ‘stretched’ over a large distance, because the individual particles are left behind were they were created. Is it possible to have the particles stay close to the car while its moving? The particle system is a child node of the car, so I was assuming that when the car moves all the different particles would move with it.

Apologies for the incredibly vague post, but I hope the general problem is clear.

you want the created particles to move at the speed/direction of the car at the moment of their creation.

-> addInfluence

For me, the smoke generated by rubber wheels on asfalt stay where they are generated (like when a formula 1 uses the brake too much)… One thing you can also try is to make the particles die faster, so there's no time to them to stay too much behind.

Other thing you could try is to make a vortex influence on them, to simulate the air turbulance generated by fast rotating wheels.

Just to clarify… you can think of the particles node to be an emitter of small objects. The position will only affect the position of the next emitted object, and not its speed or any other feature by default. Thus, the particles are not attached to the original node even if the particle emitter is attached itself. This is a more or less one-size-fits-all solution for generating effects. If you think about it, it does not make much sense for the particles to be affected by translation/rotation of the emitter node after they have been emitted. Imagine for instance an emitter on a yo-yo… the smoke would go up and down with it!!!  :-o

duenez said:

If you think about it, it does not make much sense for the particles to be affected by translation/rotation of the emitter node after they have been emitted. Imagine for instance an emitter on a yo-yo... the smoke would go up and down with it!!!  :-o

I hadn't thought of it like that, but you're right.

Actually I think I might know how to achieve the desired effect. When the car is moving with a speed of 10, the particle system should emit particles with a speed of 9, this will create the illusion of the car going faster than the particles, but not the enormous difference that exists now.

Another thing is that I only need the particle system when the wheel is locked. Currently its always there, but I set it to CULL_ALWAYS to not show it. Obviously this is a poor solution, as the particles are still being calculated. But when I attach the node at runtime there is a small delay, so that's far from ideal either...