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McC
01-09-2004, 06:25 PM
I've got a scene wherein a ship is firing at another ship. To simulate the weapon fire, I'm using LW's ParticleFX engine. A particle emitter is parented to a gun object which is in turn parented to a turret object which is again parented to the ship itself. The particles are firing at a 'speed' of 200 m/s on their relative Z-axis, plus a 60 m/s parent motion in the world Z-axis. However, when the particles emit, they start quite far away from the gun barrel where the emitter is placed. Why is this, and how can I prevent it from happening?

HowardM
01-09-2004, 07:06 PM
hmmm works fine HERE (http://www.3dink.com/testPFX.zip) in this simple scene.

whats your scale? sometimes PFX get screwey at extremely small or large scales.
are you sure everything is parented right? keyframed?
also did you hit FXstart? ALWAYS use FXstart!
:)

McC
01-09-2004, 07:10 PM
Scale's 10m.

But even in your sample scene, the particles are emitting outside of the box by about 2m.

EDIT: I take that back. When I do FX Start on your scene, they emit from within the box. However, doing FX Start on my scene (which I've tried a number of times) does not accomplish the same result.

zuzzabuzz
01-09-2004, 07:11 PM
Hmm... i get wierd effects if the parent is moving and I set the 'explosion' (but not with 'vibrate'). Make sure that is set to zero, just in case.

2nd thought: Inherit parent motion might be propelling it really far initially.

3rd thought: the emission size is much larger than the gun? Default is 1m cube?

McC
01-09-2004, 07:13 PM
Originally posted by zuzzabuzz
Hmm... i get wierd effects if the parent is moving and I set the 'explosion' (but not with 'vibrate'). Make sure that is set to zero, just in case.

Neither of these are active.

2nd thought: Inherit parent motion might be propelling it really far initially.

The parent object is only moving 60m/s across the 30-frame, and the particles are moving 200m/s. This shouldn't be part of the problem.

3rd thought: the emission size is much larger than the gun? Default is 1m cube?

Particle emitter size is 250mm.

HowardM
01-09-2004, 07:16 PM
hmm post your scene and lets look.

As for the damn 'bug' with explosion/vibrate and child emitters, the solution is to JACK UP the scale of your child emitter.
Its not too bad of a bug, just a pain in the ass now, but for a while I couldnt figure out why damnit!
:cry:

McC
01-09-2004, 07:20 PM
Scene file here (http://www.mcc3d.com/cg/RA_January.lws). Forgive the absence of the models -- their presence (or lack thereof) shouldn't affect the problem.

HowardM
01-09-2004, 07:33 PM
hmm actually it does affect it, cuz I cant see what the hell is going on here! :)

a quick look, are you sure the emitters are correctly parented to the guns?
also, never set an emitters size to 0...use 1 mm...that can cause issues....does that fix it?

tough to see with out the ships...throw in some really low poly ships and reload the scn.

McC
01-09-2004, 07:57 PM
Originally posted by HowardM
hmm actually it does affect it, cuz I cant see what the hell is going on here! :)

Heh, sorry.

a quick look, are you sure the emitters are correctly parented to the guns?

Yes and no. The model in question, while looking very good, has a number of problems on the practical level. I've been juggling pieces of it around ever since starting this scene in an attempt to make it less chaotic. So, yes the emitters are correctly parented to the guns as they are, but no, the parenting is not 'right' due to the problems with the model that I'm currently fixing.

also, never set an emitters size to 0...use 1 mm...that can cause issues....does that fix it?

Only one of the emitters in the scene was set to 0, the other three were set to 250mm. I realized this just after I uploaded, and fixed it, but it didn't change anything.

tough to see with out the ships...throw in some really low poly ships and reload the scn.

Okay, give me a few minutes.

zuzzabuzz
01-09-2004, 08:21 PM
When i load the scene, i see the particle get's born ahead of the emitter, like you described. But after I hit Scene-->FX_Start, it looks ok.

Perhaps with the standin objects, we'll be able to see what you see.

McC
01-09-2004, 08:23 PM
Originally posted by zuzzabuzz
When i load the scene, i see the particle get's born ahead of the emitter, like you described. But after I hit Scene-->FX_Start, it looks ok.

Perhaps with the standin objects, we'll be able to see what you see.

I'm attempting to experiment with this by rebuilding the scene from scratch, and it's working correctly now. I'm not entirely sure why it wasn't behaving in the original, though. It may have to do with the parenting issue mentioned above.

McC
01-09-2004, 09:35 PM
Odd. After re-parenting and re-building the scene, the emitters are behaving normally. This is something of a relief, but it also bothers me, as I've had this problem happen before, too...

zuzzabuzz
01-09-2004, 10:07 PM
:shrug:

LittleFenris
01-09-2004, 10:20 PM
I went ahead and downloaded and tried out the scene also. Same results as the others...the particles are away from the emmiter when i open the scene, but as soon as i hit FX_Start the particles come right from the emmiter, so the scene works fine on my end. just thought id give a 3rd or whatever opinion. :)

aurora
01-09-2004, 10:50 PM
OK I'm alittle late getting into this but I dl'ed the scene killed the inheritance and re-built the inheritance hit FX_Start and it worked fine for me as well. But it sounds like you got things running fine so I'm not sure if you need anymore help so I'll shutup now.

McC
01-09-2004, 10:54 PM
Thanks, but as zuzz said: :shrug:

aurora
01-09-2004, 11:04 PM
OK I just have to ask this. What kind of animation is this with objects named Corvette and TieFighter? Sounds like it could be fun to be. FYI, I did a quick render of those first 35 frame looks fun to me so far but I would work alittle more on those three explosion objects. They seem to have way to much forward momentum left to them. The explosion would tend to override that momentum to a given extent giving a more semi-spherical explosion front. But I think its a great start!

McC
01-09-2004, 11:09 PM
Heh. I was wondering if someone would ask. It's actually not an animation, but a still. The animation is just to set up appropriate motion blur for the still, which will be frame 30. It's an entry for LWG's January "Resource Appreciation" image. I'll post it here as well, if you'd like.

aurora
01-10-2004, 02:39 PM
Yes please do post it here. I would love to see it!

zuzzabuzz
01-10-2004, 04:09 PM
yeah, i forgot to mention that the scene in general was looking pretty cool. :thumbsup:

McC
01-10-2004, 08:02 PM
Here you go:

"The Fall of Night" - 1600 (http://www.mcc3d.com/cg/LWG/RA_January-1600.jpg)
"The Fall of Night" - 1280 (http://www.mcc3d.com/cg/LWG/RA_January-1280.jpg)

HowardM
01-10-2004, 08:04 PM
looks cool, but a little dark in areas, like the tiefighter on the right.

McC
01-11-2004, 02:32 PM
I've updated it several times over the past few hours -- have a look at the current version.

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