Infinity Rotation & Movement in Bullet

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hello guys.
i decide to fracture somthing like wood but i get weird result!!!
Pieces of wood after fall get infinity rotation and movment and even some Pieces jump and bounce Continuously!!!!
if you decide to use RBD Native Solver your sim time go very high!
if you decide to use Bullet Solver your sim you get weird result!
how can done this type of sim in houdini???
thanks.
Edited by - May 19, 2015 09:44:31

Attachments:
Wood Sim.hip (284.5 KB)
Problem.jpg (51.5 KB)

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Without looking at your file, take a look at your collision meshes. They are probably way off and in a round shape, which makes your pieces behave wierd. Always check your collision mesh before sim to make sure they are ok.
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Thanks for your reply.
Yes I check collision geo and set different collision padding and shrink amount for each time that I play sim but still get weird result…
I put project so if you have any idea about this problem please help me.
Thanks.
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In rayfire plugin we can create really simple and easy wood fracture effect with out get any weird result also speed of sim is very high.
https://www.youtube.com/watch?v=84cu32Scm_w [youtube.com]
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Okay I checked your hip, the collision meshes are indeed bad. See image. To fix it reduce the Collision Padding until it looks good.

However reducing the padding from the default of 0.02 can introduce jitter, so it may be better to scale everything up for the sim (the geo and any forces like gravity) - that will allow you to keep the padding at default. After the sim you can simply scale the geo back down. So for example:
Scale up geo x10 -> simulate (remember to scale gravity as well) -> scale down geo x10.

Hope it helps.

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badcollisionmesh.jpg (425.3 KB)

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thanks again scale up simulation is good idea.
but i think better way is write some expression and code in force field so for example if we have piece with high velocity and infinity rotation and movement add high force(like huge gravity force) to it also multiply velocity of piece by number less than 1.
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you can use
POP Speed Limit to limit velocities of packed RBDs
(look at from SpeedLimit example from Examples section of Help)

or you can try using POP Drag and POP Spin Drag to calm your velocities down a bit
Tomas Slancik
CG Supervisor
Framestore, NY
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speedLimit is Amazing node in simulating shatter wooden object.
special thanks for Tomas and Skybar.
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