I'm sorry for de-railing this thread, but I don't think this is worth starting a completely new topic, and it's related in a way.
After you get this thrusters system working, what about the graphics? What I've seen are costly particle systems. Would anyone find useful a new method for volumetric lights specific for this purpose? Or is it just not worth the trouble, compared to more common methods?

Quote: Original post by Jotaf
After you get this thrusters system working, what about the graphics? What I've seen are costly particle systems.

I don't know about costly, my system uses a single particle pool for each ship, roughly 20 particles per thruster while they are firing. On average each ship has 6 nav thrusters, plus a main engine using about 100 particles, so even when all are firing at once, only about 200 particles active.

Quote: Would anyone find useful a new method for volumetric lights specific for this purpose? Or is it just not worth the trouble, compared to more common methods?

I am not an expert on volumetric light techniques, but this sounds liable to take alot of development time, and quite possibly work out more costly. Also, some smaller ships may use venting gas instead of fire, and rapidly expanding gas bubbles are hard to emulate with a light.

Quote: Original post by swiftcoder
...On average each ship has 6 nav thrusters, plus a main engine using about 100 particles, so even when all are firing at once, only about 200 particles active.

That's what I'm talking about :)

In order to have a decent space battle on the screen, you'd need hundreds of ships flying around. With a particle system like you're saying, the game would dedicate much of its time to drawing a strictly cosmetic feature.
My idea was to replace each thruster with a very specific volumetric light that looks just like it was ray-traced, but it only uses a few calculations for each of the ~10 polygons.

Quote: ...Also, some smaller ships may use venting gas instead of fire, and rapidly expanding gas bubbles are hard to emulate with a light.

Ok, this part I didn't understand. I don't quite see the difference.

Quote: Original post by Jotaf
In order to have a decent space battle on the screen, you'd need hundreds of ships flying around. With a particle system like you're saying, the game would dedicate much of its time to drawing a strictly cosmetic feature.

200 particles * 200 ships is 40,000 particles, okay, that is a bit of a load, point taken. But if you can keep you game above ~5 fps while doing AI, physics, weapons, etc. for 200 ships, my hat is off to you.

My idea was to replace each thruster with a very specific volumetric light that looks just like it was ray-traced, but it only uses a few calculations for each of the ~10 polygons.

So basically you are rendering a semi-transparent cone with the tip at the thruster outlet? Another idea I have seen is just to use single billboards per thruster, and stretch it to create the correct shape of flame.

Quote:

Quote: ...Also, some smaller ships may use venting gas instead of fire, and rapidly expanding gas bubbles are hard to emulate with a light.

Ok, this part I didn't understand. I don't quite see the difference.

Think about it, nice big fusion torch is easy to do with particles or whatever.
But a fine spray of expanding gas bubbles needs a particle system.
Ok so probably in a combat game you wouldn't use this, but I was thinking of a low-tech orbiter type ship.

Anyway, something to think about,

SwiftCoder

I guess you're right on everything you're saying :)
My method is a kind of a fusion of the 2 you're talking about. But those leave out a lot of artifacts that don't look much like a volumetric light.
Anyways, I just wanted to ask your opinion about this. I'm still going to keep developing it but mostly as a volumetric light, and not so focused on reproducing a thruster! Thanks.