Vormav Posted February 17, 2008 Share Posted February 17, 2008 (edited) I'm trying to setup a mutual constraint relationship between a rigid body and a cloth. I.E., if the rbd starts falling, it should pull the cloth, and if the cloth is pulled by something, it should pull the rbd along with it. I know that in past versions of DOPs, this couldn't really be done (afaik). However, one particular DOP example from the 9.1 docs keeps jumping out at me: ClothSpringsBalls. As far as I can tell, that example has managed to produce a mutual constraint relationship between rigid bodies and cloth. They use an sbd spring constraint, constraining a point of the cloth to a point of the rbd. Then 'mirror' is turned on, and it seems to work. If I increase the mass of the balls, they pull the cloth down. If I blow a fan at the cloth, it pulls the balls with it as it moves up. However, I haven't been able to reproduce the effect. Any time I try to use the setup they've used, Houdini complains that the "constraint could not be processed by solver." The RBD Solver just won't have any of it - and I have no idea why it's working in the example. Even if that didn't work, it seems like this ought to still be doable... It should just be a matter of setting up a spring constraint - constraining a point on the cloth to a point on the rbd - then, grabbing the force data contained in the state of that spring constraint, and applying it as a 'point force' at the position on the rbd where the spring constraint is hooked up. ...right? But, although I can track down all of that data in detail view, I can't figure out how exactly I can apply it, if I even can. And there's always the chance that I'm missing a very simple solution to this. Any tips? Edited February 17, 2008 by Vormav Quote Link to comment Share on other sites More sharing options...
Vormav Posted February 17, 2008 Author Share Posted February 17, 2008 (edited) Nevermind, I figured out why it wasn't working: I had setup a glue relationship between my rbds that shared the constraint with the cloth object, and another rbd. Somehow, that glue relationship breaks the RBD Solver's ability to handle a two-way cloth<>RBD relationship, so you have to setup the glue-like relationship between the rbdobjects using other methods. It's working now. Edited February 17, 2008 by Vormav Quote Link to comment Share on other sites More sharing options...
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