Art Tasks - to do

[Springheel]

I'm looking for people who are able/willing to take on the following tasks:

 

Particle Effects

- hand-held torch flame (that moves as AI moves like TDS?)

- magic arc-light particle (to go with existing model)

- buzzing flies particle effect (for dead bodies, garbage, etc)

 

Improve candle flame particle (flicker needs to be increased) -- http://forums.thedarkmod.com/index.php?showt...hl=candle+flame

 

 

I know nothing about particle effects and doubt I'll have time to learn any time soon.

[SneaksieDave]

(that moves as AI moves like TDS?)

Not sure what you mean by that. If it's attached to a held torch, it would move with AI, if that's what you mean.

 

Is the walltorch flame unusable? Too big, I'm guessing?

 

Improve candle flame particle (flicker needs to be increased)

As in side to side? If that can be done programmatically (actually moving the attachment origin, as with the light origins), that might be the only way. The whole cluster of particles would have to be jittered back and forth as a whole to look right, and there seems to be no way to do that with particle editing. Jittering individual particles around just spreads the flame out and looks lousy.

[Springheel]

Is the walltorch flame unusable? Too big, I'm guessing?

 

Yeah, that one is too big to be used so close to an AI.

 

If it's attached to a held torch, it would move with AI, if that's what you mean.

 

Does the flame just stay going straight up, or does it kind of trail behind when in motion like they did in TDS (though perhaps not so extreme)?

 

http://www.mbnet.fi/pelihalli/uutiset/isok...1254&kuva=1

[SneaksieDave]

As far as I know, once spawned, the particles "do their thing" with regard to their world position, not where they originated from, so they should trail. IIRC, the lost souls (and thus the fire elems) trail fine, and there was nothing special about those particles that I know of.

[Gildoran]

I'm not sure if I'm understanding you, but a normal particle system doesn't leave a trail, since it's parametric; when you move the origin, the whole particle system moves, as though each particle were bound to the origin. (you can even do things like rewind time by editing their shader-parms) In order to get trailing, you need to use a smoke system. However, smoke-systems are always calculated, so you only want to have a few on a map at the same time. In a game like D3, it's ok to use smoke systems for things like muzzle-smoke or perhaps flaming shrapnel, since they only have smoke for a short time, and that short time will only be when the player is nearby. In a game like TDM, where you might have several guards in the map with torches, you want to avoid using smoke systems for torch fire.

[OrbWeaver]

I guess the problem is that particle systems are bounded entities like any other, so the particles have to be specified relative to the emitter. Presumably a smoke system is a particle emitter with infinite bounds, or something.

[Gildoran]

I don't think it has to do with bounds... what I'm saying is that normal particle systems don't keep track of the individual particles... You give it a time, variation and position, and from those three variables it will generate the current state for the entire particle system, figuring out which particles exist, and where. It doesn't pay any attention to where particles were the previous frame.

 

Smoke systems are more like most engines' particle systems - a smoke system keeps track of where each particle is located and applies movement/etc to them each frame. This has the advantage that you can have smoke trails, but the disadvantage that in order to calculate the next frame, it needs to know about the previous one - so smoke systems need to be calculated each frame to be correct.

[OrbWeaver]

I don't think it has to do with bounds... what I'm saying is that normal particle systems don't keep track of the individual particles... You give it a time, variation and position, and from those three variables it will generate the current state for the entire particle system, figuring out which particles exist, and where. It doesn't pay any attention to where particles were the previous frame.

 

That is very interesting, I was thinking about this when considering how to implement the DarkRadiant particle editor (a future task, not even started yet). I was thinking it might be good to have a sort of "progress bar" like you get in media players, which would allow you to drag it to any position and see the particle state at that point, but that would require the particle system to be a deterministic function of time, which I was assuming it wouldn't be. It sounds like in Doom 3, it actually is.

 

Smoke systems are more like most engines' particle systems - a smoke system keeps track of where each particle is located and applies movement/etc to them each frame. This has the advantage that you can have smoke trails, but the disadvantage that in order to calculate the next frame, it needs to know about the previous one - so smoke systems need to be calculated each frame to be correct.

 

I guess this requires more memory as well, because each particle's position needs to be stored and updated. The deterministic function of time implementation requires no state to be stored at all, rather the function can just be called from scratch each frame with a different time value.

[SneaksieDave]

Okay then it sounds like the following would work:

-I'll edit the torch particle to make it suitable for a hand-held

-somehow define this particle as a smoke (no idea how to do this - I looked at, for instance, the lost soul flame in the particle editor, and it didn't seem any different - hints are welcome)

 

Incidentally I tried a simple torch flame attached to an AI with bind (not sure how to do the formal attachments at this time - I tried using RightHand, tried replacing the sword with a light entity and/or flame particle - didn't work. I was able to bind the lost soul flame, but that's a smoke I assume, so it doesn't help - sure gave some ideas for fire mages though, with burning hands...), and anyway, it didn't look all that bad. Yes, it doesn't trail, but the particles are short lived enough that even if the existing was all we had, it wouldn't be so bad.

[SneaksieDave]

Now up on CVS is particle: tdm_fire_torch_small

 

It's about 50-75% the size of the other one. I tried even smaller than that, but it looked dorky (or too cute, depending on perspective). It is not this mystical "smoke" type of particle yet - I'm as of yet unaware how to do that.

[SneaksieDave]

Also now on CVS: tdm_flies

 

Turns out Doom3 had a fly decal and a fly particle. I took theirs and adapted it a bit (more flies, they cover a slightly larger area (was too small), last longer, and rotate in flight).

 

Interesting tidbit learned from this I didn't previously know - particles can be lit, afterall. Plant some flies next to a light, stop time, and you'll see. I guess it's a matter of how the texture is defined, and not a limitation of particles. Hmmmmmm...

[SneaksieDave]

Figured out how to use the particle as a smoke. The results are less than great.

 

http://208.49.149.118/thedarkmod/movies/torch1.wmv

http://208.49.149.118/thedarkmod/movies/torch2.wmv

 

The first is obviously as a simple particle, when all particles stay within the bounds of the model. The second is the very same particle (believe it or not) as a smoke. In my opinion, even though the first is not as high-tech-groovy, it looks better. The smoke streams back waaay too much, and it even seems to damage the particle - it flickers at the bunching point (the regular particle doesn't show this effect), the smoke puffs (again, regular doesn't show this effect), and the blue swirl at the heart of the flame flickers on and off (again...). I don't know if smokes have limitations, or they're just more demanding because they have to update position in the world constantly or whatever, but IMO it doesn't look very good. Perhaps the particle could be tailored to look better when walking, but then it would look bad when standing still. Neither is perfect, but the plain ol' particle looks better, to me.

 

Hmm.. we could always use a separate smoke particle as the smoke entity, and not the whole flame particle... that might look okay.

[Gildoran]

Interesting tidbit learned from this I didn't previously know - particles can be lit, afterall. Plant some flies next to a light, stop time, and you'll see. I guess it's a matter of how the texture is defined, and not a limitation of particles. Hmmmmmm...

Yeah, I've always thought "particles can't be lit" was a load of bull (thanks to D3 using a unified rendering system). Anyway, lit particles are how I constructed the volumetric lighting effect.

 

The first is obviously as a simple particle, when all particles stay within the bounds of the model. The second is the very same particle (believe it or not) as a smoke. In my opinion, even though the first is not as high-tech-groovy, it looks better.

I think the reason the smoke doesn't look as good is because the particles aren't rising fast enough, so it looks way too slanted.

 

However, I advocate avoiding using smoke for anything of a persistent nature (eg, torches held by guards). Floating skulls may have been able to get away with it because there were only a few in existence at any one time, but if we have numerous fire-elementals or torch-holding guards roaming a map and they each have a smoke effect, it could slow down the map to a crawl.

[Springheel]

Hmm, is there no way to tailor how much the 'smoke' is affected by movement? I agree that the version you posted probably isn't worth doing if that's the best it can do. But if there were a way to make it less slanted, that might be worth it.

[OrbWeaver]

Hmm, is there no way to tailor how much the 'smoke' is affected by movement? I agree that the version you posted probably isn't worth doing if that's the best it can do. But if there were a way to make it less slanted, that might be worth it.

 

The slant will be a function of the rising speed of the particles and the horizontal speed of the binding point. To make it less slanted you will need a faster rising speed or a slower horizontal motion.

 

However, I advocate avoiding using smoke for anything of a persistent nature (eg, torches held by guards). Floating skulls may have been able to get away with it because there were only a few in existence at any one time, but if we have numerous fire-elementals or torch-holding guards roaming a map and they each have a smoke effect, it could slow down the map to a crawl.

 

Will smoke effects be simulated even if they are out of PVS? Perhaps there is scope for optimisation if they can be turned off when not visible (although maybe this is not possible if the whole purpose of smoke is that they particles ARE rendered when the emitter is not visible).

[SneaksieDave]

But like I was saying above - if the particle is tailored to look good when walking, it won't look the same when standing still - then it'll be hyperactive wacky superfast flame. It won't be consistent with the established flames (fireplace, torch), either. I don't see it as worth it.

 

Instead (also said above) perhaps the flame should be a standard particle (emitting upwards) and the smoke alone should be a smoke. I'll try that when I get home tonight if I get a chance.

[Springheel]

Hmm. This is a bit of a pickle. While the non-moving particle effect looks passable while walking, I wonder how it will look when the guard is running or otherwise moving fast?

[OrbWeaver]

It seems counterintuitive that there shouldn't be a setting which works in both cases. After all, in real life the flame particles move upwards with a certain speed and acceleration, which AFAIK does not change (maybe a little, but not much) when the flame is moving.

 

It may be that there is a tendency to underestimate the speed at which a static flame should rise, just as there is a tendency (at least in my own experience) to make water ripples too slow and look like treacle.

[SneaksieDave]

Well also, in reality, a person walking with a torch imparts some forward velocity (or is it technically momentum? p=mv? physics was a long time ago, I forget) on the flames, I would assume? So they're moving forward even if just a bit, whereas these particles have no velocity at all, and stay fixed w/r/t the world.

 

Speeding up the flame particles to compensate could be an option, but I'm reluctant to mess around with what I think is a good looking particle at this point (it would take a substantial speed change probably). I've still got to try the smoke as smoke though... was thinking about it and it makes sense - flames move fast, so they'd tend to stay upright; smoke is slow moving and is basically just air - it makes sense for it to lag behind.

[OrbWeaver]

Well also, in reality, a person walking with a torch imparts some forward velocity (or is it technically momentum? p=mv? physics was a long time ago, I forget) on the flames, I would assume? So they're moving forward even if just a bit, whereas these particles have no velocity at all, and stay fixed w/r/t the world.

 

Yes, you're right. I'm not sure how much of an effect that will have though, since I imagine the horizontal velocity of the particles will fall to zero due to air friction pretty much immediately they have left the flame source.

 

Speeding up the flame particles to compensate could be an option, but I'm reluctant to mess around with what I think is a good looking particle at this point (it would take a substantial speed change probably). I've still got to try the smoke as smoke though... was thinking about it and it makes sense - flames move fast, so they'd tend to stay upright; smoke is slow moving and is basically just air - it makes sense for it to lag behind.

 

Separating the smoke and the flame in that way sounds like a good idea.

[SneaksieDave]

Here's a mockup of a split flame and smoke system. It's a little hard to see the smoke at this movie quality, because it's so wispy, but it looks pretty good, and better than the previous two setups (choo-choo train style, and 'torch-in-a-bubble' style).

 

http://208.49.149.118/thedarkmod/movies/torch3.wmv

 

To try this little mockup yourself, bound to the guard are:

-a light

-a func_emitter of "model" "tdm_fire_torch_small_no_smoke.prt"

-a func_smoke of "smoke" "tdm_fire_torch_small_smoke.prt"

 

New on CVS: tdm_fire_torch_small_no_smoke, tdm_fire_torch_small_smoke