Allow a method to reverse ParticleEmitter's direction


At the moment it’s not possible to get a particle effect to appear at an outer-most point, sending particles towards an origin point. (Reverse particle direction)

I had an idea involving a way to make the speed property of particles negative. What this would do is simply make the particle’s position the same as if it were at the end of its lifetime at a positive speed (so in a way, pre-calculate the end position of the particle) and then move it towards the emitter’s origin.

This is a fairly simple idea in terms of explanation but it would make room for quite a few effects that developers can use. Many effects people would love to make rely on this out->in direction, so I think the use cases are more than present enough for a demand on this feature.

What do you all think?


Really good idea, even though I (and others I know) have thought of having reverse-particles would be cool, we never thought to make a feature request.

Currently the only way you can do anything like this is by decreasing size on large, stationary particles, which isn’t very cool.


Yes I hope this happens because with the current way ParticleEmitters work,
you can make Explosions (In->Out) but not Implosions (Out->In).

There is no current way to do that with just one ParticleEmitter.

You would have to make like a ring of tiny invisible parts with a ParticleEmitter in each one, aligning the front face of each part towards a center point, and having the emitters go from big to small as it reaches the center point to give it that Black Hole effect.

Edit: Also this would make it possible to do reverse time effects. Say you are doing a cutscene and a car blows up. You use a particle emitter to do the explosion while parts fly everywhere. But then the cutscene slows down and then stops, part movement is frozen still. Then time reverses and everything goes back to the car and the car fixes itself as if the explosion never happened. This is possible but with one exception, the ParticleEmitter wouldn’t stop, it will keep its exploding out effect during the time reversal. So this is one use case where a reverse property or something would come in handy.