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Brötje
11-22-2013, 06:00 AM
Hi all,

I have this very cool fractured tree that bursts in pieces when a dinosaur runs through it. I want to emit dust and debris when the breaking occurs. The easiest way is to emit particles from the interior polygons and use HV/Instancers.

BUT.... I can't control the emission from the surface. I can either choose to emit from the entire object surface of nothing at all. And controlling the emission with A UV map on the birth rate does nothing. Painting a weight map on the desired areas would be an option, but I can't choose weight maps in the gradient options.

So how do I go about that this problem? Is there a workaround? Any other options?

Cheers!

prometheus
11-22-2013, 02:53 PM
I donīt think you can use uv map projection for birth rate, but not sure, image maps can be used, but can be tricky, you have to set the right mode like multiply or alpha and maybe even calculate for
best results.

Weight maps donīt work unfortunatly for particle birth, we could have use of that, but we have to keep or hopes up for that one in the futue.

there is a fire and smoke generator plugin (commercial) from pawel olas, which has itīs own particle engine that can actually use weight maps, not sure how well it works
with Lightwave 11.6 though, it also has vorticles..meaning particles them self affect particles around them with a vortex field, wich we donīt have in lightwave native particles.

http://www.polas.net/smoke/index.php
http://www.polas.net/tutorials/tutorial05.php
and more tutorials on how to use the fire and smoke generator...
http://www.youtube.com/watch?v=ZRUFJpurGCw

Otherwise I think you should try and make proxy collision objects, and proxy emission objects, but depends on how your geometry looks like and how it is fractured and with what
dynamics engine, you could use proxy collision objects hitting proxy emission objects and make them emitt by collision event, the tricky part would be to parent proxy emission objects
to the fractured parts.

The old hardfx engine can read fractured pieces motion path, and from there you can make path and assign nulls to the fractured pieces, and then make the tracked nulls as an particle emitter.
Edited..noticed that you want more of the debris and dust style.
Think you have to manually place or track some pieces or add collision emitters as I mentioned first, I dont think you would need super accuracy here, and that placing
collision emitters based on collison event on proper places will do, or keyframe it, you can have emitters generate by key, so it starts emitt based on if you set a keyframe there.

colkai
11-23-2013, 03:19 AM
It's probably a terribly laborious procedure, but you could import your scene into Blender, do the particles there then export back out for Lightwave as Blender allows particles based on wieght map painting.
Though I'm only just getting into this but I would imagine the biggest issue is the saving of all MDD data, which may make it far more trouble than it's worth, dunno, not tackled shifting heavy scenes back and forth yet.

Thomas Leitner
11-23-2013, 07:46 AM
I donīt think you can use uv map projection for birth rate, but not sure, image maps can be used, but can be tricky, you have to set the right mode like multiply or alpha and maybe even calculate for
best results.

Weight maps donīt work unfortunatly for particle birth, we could have use of that, but we have to keep or hopes up for that one in the futue.


Particle emitter ignores UV-texture to regulate Birth Rate. Itīs a bug that I have reported 1 year ago....

....so I have stopped hoping....

ciao
Thomas