Has anyone tried out Bullet dynamics in houdini?

[ganzou]

I've been using Bullet solver for houdini and it is really fast compared to RBD solver or ODE, only thing is that I cant manage to get collisions out of imported geometry. I'm importing some maya geo through fbx and slicing it up with voronoi sop and putting that into dops...gravity works , but I cant get the pieces to collide with the ground object.

[krizard]

nop...actually i am doing a research but there isn't to much info about it in the net.... or i am a bad researcher???hahahha
but tell me about it ....is it free???if its not , how much does it coust??what are the advantages except simulation speed???

[ganzou]

Well I have updated info on it since my first post:

First of all to answer your questions...Bullet is basically an open source dynamics engine. Meaning it is all the source code you need to build your own dynamics plugin for your choice of 3D app and since it is open source...yes it is free. It was used in 2012 for the dynamics of the LA shot where buildings start collapsing and hitting each other. They build it as their own dynamics engine for use within houdini and it was called DROP. From several articles I have read they state that no other available solution could tackle the amount of destruction they were going for with reasonable speed. Instead of waiting overnight for the sim to complete they waited an hour or two which means it was blazing fast considering the amount of geometry in the collision array.

Apart from simulation speed which is incredibly important with dynamic sims ...this engine can also handle the original mesh to be used as the colliding object. Most other dynamic engines use primitives or bounding boxes to represent the colliding object or some approximation. But this engine uses the original mesh with no noticeable sacrifice in speed and is very very accurate.

One "disadvantage" is that BULLET is just a dynamics library. So basically it is just the source code which means that one must make their own dynamics plugin based on that code. Which in turn means that you wont find it built into any 3d app.

Disney released their own dynamics engine DINAMICA which was created using BULLET sdk and can be found for maya. I have used it and it is good enough. The good thing for BULLET is that it is currently being integrated to use openCL which will enable it to use both cpu and graphics cards for processing and this will really make it dominate.

I compiled a version made available for houdini (linux only) and right now it is limited to just fractured pieces. No glue objects. But I have made some cheats to get the fractured geometry to hold in place. I have been testing out collisions of random objects at random quantities and I must say that even though this plugin build I obtained is quite limited....it in itself does show off the potential of this solver and it is really really fast.