Particle System

Thedude · Post by **Thedude** » Wed Jun 30, 2004 5:01 am

How would I make a smoke trail that dosn't follow the object which created, kinda like a jet smoke trail, and help would be nice

Electron · Post by **Electron** » Wed Jun 30, 2004 12:27 pm

don't make the emitter a child of your moving object.

Guest · Post by **Guest** » Sun Jul 04, 2004 11:13 pm

I mean in the sense that, the smoke emitter will follow the node, but when it emits the smoke it shoots it in the direction-180 of the object its following

Electron · Post by **Electron** » Mon Jul 05, 2004 12:48 pm

Well IParticleSystemSceneNode::createGravityAffector can help you. I don't know if that's exactly what you want, but if you amke the gravity sideways it should come out decently

Alex · Post by **Alex** » Tue Jul 06, 2004 4:13 am

IIRC each particle in a system is relative to the node the system is attached to. This means if your jet or whatever is rotating and moving each particle will rotate and move in accordance with that. This can look quite silly especially if you have long smoke trails.

Unless you can set the particle positions to be absolute rather than relative (move on their own rather than sharing position data with the node) you may have to make or derive your own smoke particle system.

An easy solution would be to create a billboard every couple of frames relative to the jet, which has its own position data and lifetime variables like size, color, etc.

I promise you if you attach the emitter to the object, it will look funny. But don't take any ones word for it, try it for yourself

Electron · Post by **Electron** » Tue Jul 06, 2004 12:15 pm

Yeah, you're right, for jet trails it would look funny

Thedude · Post by **Thedude** » Wed Jul 07, 2004 4:38 am

I tried rotating the object it was following and it looks weird. Plus I tried using billboards but they seem to slow it down a bit (only a bit). I tried all this before I asked, I was just wondering if there where any other ways

Alex · Post by **Alex** » Wed Jul 07, 2004 7:31 am

Particle systems are basically a bunch of managed billboards so you should be able to create your own billboard system that emulates a smoke trail quite easily.

Using billboards is the only feasible approach to my knowledge, could you provide some more details about the billboard approach you tried, like source code or something.

One thought could be to derive a new class from the particle system that tracks the world position of its parent node and adds/subracts the change in position/orientation since the last update from each particle, meaning that no matter how much you rotate and scale and shift a node, particles in your derived system will not be affected.