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View Full Version : Bullet Dynamics in LW 11.6: missing bits..?



Hieron
08-26-2013, 03:44 PM
Been using/fighting ClothFX for a long time now and eager to switch over to Bullet as it seems to be the successor to the old FX plugins. Primarily interested in deforming objects to do stuff like:
http://www.nymus3d.nl/player2.php?id=85&lan=nl
see at 0:30s. Note how cells divide, change shape (relatively drastically) etc.

Am I right to say that:
-One can not easily activate a dynamics object at will at time/frame x? Or turn off collisions for a while.
-Morphing the object is not as nicely followed as ClothFX does it. it requires a reasonably high shape retention, basically turning off dynamics to a high degree. Is this a deformer stack issue? Why can the new morphed shape not be the "intended" shape, it seems to refer whatever was at frame 0 to be the base shape. This is not useful..

Most examples/content seem of the simple "drop stuff on table" type or the minor jiggles on an animal. Hopefully someone has some better experiences to share.

VonBon
08-26-2013, 07:34 PM
Maybe use HVs for the splitting cells and track the point info of the HVs with nulls
and use the nulls to deform the surrounding cells.

Use morphs and comp for the first part (from yellow to green)
Softbody Dynamics should work for the first part though.

MetaBalls? Im shootn in the Dark here :)

khan973
08-27-2013, 09:15 AM
The major issues I found are:

Unable to launch at X frame as well
If you're at frame let's say 1500, if you run the sim, it calculates in a hidden way from frame 0...
There is no group, so no way to ask some parts to ignore each other
No way to launch sim at an event (ie collision)
I don't know why it hasn't move in one year. I hope they get back to it to improve it.

RebelHill
08-27-2013, 09:26 AM
-Morphing the object is not as nicely followed as ClothFX does it. it requires a reasonably high shape retention, basically turning off dynamics to a high degree. Is this a deformer stack issue? Why can the new morphed shape not be the "intended" shape, it seems to refer whatever was at frame 0 to be the base shape. This is not useful..

A mesh in layout looks one shape, but underneath it has many shapes... The base shape, the base shape after regular transforms, the base shape after bones, the base shape after morfs, the base shape after bones+morfs, etc, etc for every possible kind of displacement or combination thereof.

Bullet "sees" transforms (exculding scale) and bone based displacement... and I *think* thats it... so no draping a cloth over a morfed shape, displaced shape, etc. Or maybe it sees those shapes too but only "once" as in frame 0... Something like that or other anyhow.

Emmanuel
08-27-2013, 10:48 AM
Now that looks to me like softbodies, each cell has another cell oject inside, which at a given time moves out, it looks like inertia is applied to ive that stretching effect at the beginning. Looks easy.

Hieron
08-27-2013, 10:56 AM
Now that looks to me like softbodies, each cell has another cell oject inside, which at a given time moves out, it looks like inertia is applied to ive that stretching effect at the beginning. Looks easy.

heh lol, you do realize it is our own work I was referring to?
Yes it is possible in ClothFX, I grant you it is not "easy" and your suggestion would have a lot of pitfalls. Try it, use 100+ cells and do 10+ divisions, sometimes on the same original cell. Enjoy the "ease".

- - - Updated - - -


......Or maybe it sees those shapes too but only "once" as in frame 0... Something like that or other anyhow.

yeah I think that is it.. in any case it is more limited in this vs old ClothFX