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AC9000
11-15-2012, 12:30 PM
I have a simple setup consisting of a sphere, that has been fractured, falling onto a ground plane. I have tried to add a particle emitter to act as dust when the sphere fractures on the ground. The emitter works, until I set it to collision event. Then the particles disappear and do not seem to be emitting anywhere, anymore. Help

rcallicotte
11-15-2012, 12:59 PM
Might want to try another thread. This is the General Discussion. I don't know enough to help you. You will probably need to be more specific in your question about the collision event and its connections to the way you setup the particles.

MarcusM
11-15-2012, 01:02 PM
Maybe check what you set up in Interaction (None, Bounce, Drag..)

jeric_synergy
11-15-2012, 01:20 PM
I dunno, this seems fairly 'general' to me. ANYWAY:

Step back and make the simplest possible scene that involves collision triggering, just to make sure you're not forgetting something.

if BULLET is in charge of the displacement, it's possible that LW thinks the OBJECT is still at its keyframed location, and hence no collision is occurring.

One way around that {may be/is} to use nodal motion to 'glue' a null to a given point on the fracturing object, and use the NULL to trigger the collision event. RH covers this in his 3part video tutorials on nodes (it's pretty basic), and I heartily recommend the entire package. Available from Liberty3D (http://www.liberty3d.com/store/).

AC9000
11-15-2012, 01:22 PM
Thanks, but that didn't have any effect.

AC9000
11-15-2012, 01:30 PM
Thanks, jeric. So, I still need to create a collision event, even though bullet knows that it is in fact colliding, already? How does Bullet communicate with the other FX created, or can it? How would you set this scene up? How would you create a scene like this, with a sphere falling onto a ground plane and fracturing, and giving off dust as it fractures? Thanks again for your time.

jeric_synergy
11-15-2012, 01:48 PM
Thanks, jeric. So, I still need to create a collision event, even though bullet knows that it is in fact colliding, already? How does Bullet communicate with the other FX created, or can it? How would you set this scene up? How would you create a scene like this, with a sphere falling onto a ground plane and fracturing, and giving off dust as it fractures? Thanks again for your time.
Well, it's pure speculation on my part: BULLET might know things are colliding, but does it pass that info to the old systems?

When you look at the wireframe of a HARDFX, SoftFX, or variously displaced object in Layout, you see the bounding box is still back where it was keyframed. This is the basis for my speculation. Also, that BULLET is new and HardFX (or whatever) is old and not very sophisticated.

I can't build you such a scene (unless you pay me), but in general it's a good idea to do a simpler PROOF OF CONCEPT scene to make sure that things actually work as you expect. At the very least, the simpler scene calculates faster. But often it will clear your mind of irrelevancies that may be concealing fundamental issues.

I think you're on the right track: find out how to attach nulls to specific points in nodal motion (it's easy, try YouTube) and you'll be almost there.

UnCommonGrafx
11-15-2012, 02:21 PM
You would need to fake some event occurring because Bullet won't kick in event action with anything prior to it.

So, throw a null in the mix where you want dust to fly, making it a collision object, and you should be good to go.

AC9000
11-15-2012, 04:10 PM
Jeric - thanks for the advice. I see what you are saying, but I am not doing some crazy project. I am only using a very simple setup in order to figure out how the particles work. Like I said, I am just starting to use LW. I understand what you are talking about with the null and I will try that method. It seems that the Bullet system is a big black box, meaning that you do not have much control over what is going on inside of the effect.

Uncommon - Thank you as well. I was just thinking about faking a collision event or something along those lines. I will continue to mess around and let you know what I come up with.

Thank you again for your time.

A

Areyos Alektor
11-15-2012, 05:44 PM
Bullet does not yet react with the rest of LightWave but it's possible to use the MDD I think to work around the problem. More is coming with the 11.5

If you begin with LightWave you should know that the use of Nulls is common because it's a proxy that takes up little resources and which does not appear to render. It's also very convenient as controller (including viewing "Item Shape": "Object Properties" / "Geometry" / "Add Custom Object").

Often this prevents many problems to use them or a 2 points polygons chain.

Areyos Alektor
11-15-2012, 05:44 PM
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AC9000
11-19-2012, 11:21 AM
Thanks, Areyos! I understand null usage. That sounds like the key to this challenge. I will let you know how it goes.

Aaron

XswampyX
11-19-2012, 03:03 PM
Bullet does not yet react with the rest of LightWave but it's possible to use the MDD I think to work around the problem. More is coming with the 11.5

If you begin with LightWave you should know that the use of Nulls is common because it's a proxy that takes up little resources and which does not appear to render. It's also very convenient as controller (including viewing "Item Shape": "Object Properties" / "Geometry" / "Add Custom Object").

Often this prevents many problems to use them or a 2 points polygons chain.

This works. If you bake out your bullet simulation to a MDD file and then use that you can add alot of particles! :D


http://youtu.be/kkBaB37T9iE

jeric_synergy
11-19-2012, 04:24 PM
So, the traditional particle system can detect Part collisions when displaced by MDD?? :stumped:

That object is all ONE object, right? Is there some legerdemain with nulls in that animation?

XswampyX
11-19-2012, 04:53 PM
Legerdemain.... I had to look that up. :D

It's just two objects. The floor and the blocks (125 simulated as parts in bullet).

Edit for bad maths and there is a null in there, but it's only for generating a particle trail off the collision particles.

jeric_synergy
11-19-2012, 05:07 PM
Legerdemain.... I had to look that up. :D
An extensive vocabulary has made me the animator I am today. :cry:

It's just two objects. The floor and the blocks (125 simulated as parts in bullet).

Edit for bad maths and there is a null in there, but it's only for generating a particle trail off the collision particles.
Since the pivot point is back where where the object thinks it is (ie where it is keyframed), is straight geometry Collision triggering the 2ndary particles?

XswampyX
11-19-2012, 05:15 PM
No the collision of the MDD file creates the 1st partlcles (in yellow, the collision particles) and then the null is made into another particle emitter and parented to the 1st emitter to create the "trails" that follow the collision particles in blue.

It looked nicer than just billowing HV's floating around. Think fireworks.

jeric_synergy
11-19-2012, 11:19 PM
See, that surprises me: I thought Displaced geometry was not detected by the collision routines.

Thomas Leitner
11-20-2012, 01:00 AM
This works. If you bake out your bullet simulation to a MDD file and then use that you can add alot of particles! :D

You donīt have to bake out the bullet simulation to use it as a emitter or collision object for particles. But I prefer to write MDDs when my bullet simulation is done, too.

Ciao
Thomas