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ranxx
05-09-2007, 10:12 PM
hello all, I'm having a frustrating problem with a scene which seems like it should be simple. I have a ball with a lattice parented under it. The lattice is a softbody, and the particles of the softbody are connected to walls which the ball collides with. The particles of the softbody are also connected by springs. The animation of the ball group is keyframed. The problem I am having is this .. it seems that after the first collision (which looks good), the position of the ball is not correct according to the keyframed motion. I think what is happening is that the particle collision is moving the softbody, which is parented under the ball, so it's kind of a double transform going on. I really just want the keyframed ball to react to collision geometry without using goals (goals seem to add a secondary movement which doesn't look very good). Is there a way to get rid of this secondary transform ? I hope I am being clear. thanks

-ranxx
mandark1011
05-10-2007, 10:43 PM
how did you create your lattice softbody? was it duplicated and goaled to the original? if so it may be because the goal weight isnt high enough.....since you mentioned not using goals i would look at your dependency from the sounds of it your "parenting" structure may be causing the double transforms
ranxx
05-10-2007, 11:05 PM
how did you create your lattice softbody? was it duplicated and goaled to the original? if so it may be because the goal weight isnt high enough.....since you mentioned not using goals i would look at your dependency from the sounds of it your "parenting" structure may be causing the double transforms


this is how I made my softbody:

To make a lattice a soft body




Select the lattice.
Select Soft/Rigid Bodies > Create Soft Body > file:///C:/Program%20Files/Alias/Maya8.0/docs/Maya8.0/en_US/Dynamics/images/optbox.gif to display the options window.
From the Creation Options menu, select Make Soft.
Click the Create button.
Connect the soft body to the field you want to use to deform the object.
at this point I connect the particles of the softbody to a plane for collisions, then I create springs for the soft body structure. The parenting structure is definitely causing the double transform, but I'm not sure what to do about it (the particles have to be a child of the lattice, the lattice has to be a child of the object).

thanks for any ideas anybody might have, I seem to be stuck and am looking at other solutions.

-ranxx

edit:

p.s. my scene doesnt exhibit the behavior if I don't create springs on the particles.
mandark1011
05-11-2007, 02:10 PM
The particles should exist outside your hierarchy. they will follow the lattice as is and when you create a lattice you also get a base lattice object ie. the lattice before deformations. Put your base lattice within your parenting structure but leave the deforming (soft ) lattice outside.

If this doesnt work post a screen grab of your hypergraph parent hierarchy that should help clear up whether this is a parenting issue or not

One other thing worth mentioning at this point is you may not be getting a double transform at all it may be your spring behavior that is causing what looks like a double transform...in my experience springs are very sensitive and take alot of adjustment to get the right behavior

didnt see the ps part about springs..yah they are tough to get the proper behavior from them
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