Bullet Usage in Fabric/modo

malbrechtmalbrecht Fabric for Houdini Posts: 752 ✭✭✭

Moin,

continuing a discussion in the feedback thread, I thought we could discuss Bulleten* here.
I find the "boxes sample" in samples/canvas quite good to get a start at converting Bullet examples into Canvas ("noodle") graphs.
In general it surely helps to read bullet's documentation and look at the code samples, but maybe we can collect questions/answers here as well.

Marc


  • Bulletten: Pun on the German word "Bulette" which means rissole.

Marc Albrecht - marc-albrecht.de - does things.

Comments

  • malbrechtmalbrecht Fabric for Houdini Posts: 752 ✭✭✭

    One thing to keep in mind is that in modo all bullet features are "properties" of a mesh item, while in actual bullet implementations the visible geometry has nothing to do with what bullet is dealing with.

    The best comparison you can get is looking at how dynamic colliders in modo's particle system work: There you can (just like in bullet) actually plug in a different collision shape into the collider, while the replicator (the displayed item) can be completely different. You are not limited to bullet's "primitives" (box, sphere etc), but can plug in any mesh, even completely different ones to the displayed geometry.
    That is how bullet works: If you want to deform a mesh based on physic simulations, you have to "manually" adjust the mesh's shape according to the collision shape. So you will, usually, have two "lines" in your graph - one for the collision shape and actual bullet simulation, one for the displayed geometry.

    Marc


    Marc Albrecht - marc-albrecht.de - does things.

  • OlivierDOlivierD Posts: 13

    Thank you for this thread, I think it's a very good start. I will put some scenes here and some questions. I'm gonna study this "boxessamples" scene to understand how it works.

  • OlivierDOlivierD Posts: 13

    Just wanted to add that I learn a lot from this scene. The result of this scene can be seen in canvas, not in Modo, because, I suppose, as you explain, I have to adjust a Modo mesh to the collision shape of Fabric.
    I'm just actually looking into this file to better understand it.

  • malbrechtmalbrecht Fabric for Houdini Posts: 752 ✭✭✭
    edited March 2016

    Hi, Olivier,

    here's the graph for modo - all you have to do is create a single polygon mesh onto which you combine the "instances" (as clones) - and make sure to not have an unsupported port exposed to modo as that creates an error message and stops the output.

    I have to take a nap ... accounting day on Saturday ... but I'll be back (muahaha!) :)

    Marc

    P.S. If you want the simulation to work in modo, rename the input timeline port to "time" and connect it to a time-channel-modifier in modo. You cannot "scrub back" (which you can not in modo either if you are life simulating), but you can have the simulation run.


    Marc Albrecht - marc-albrecht.de - does things.

  • OlivierDOlivierD Posts: 13

    Thank you, it's very clear. Help very appreciated !

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