[Sidefx-houdini-list] using OBJNAME to build RBD constraints

Ben Schrijvers ben.schrijvers at guerrilla-games.com
Wed Aug 26 10:37:57 EDT 2009

Hi there,

I've got a bunch of RBD objects in Dop's and a matching bunch of 
(animated) points in Sop's.
Now I want to constraint each RBD object to the corresponding goal point.

I've allready brought the goal points into Dop's using an Empty Object 
Dop and Point Position Dop.
I can create a constraint with a rbdSpringConstraint for a single RBD 
Object and that works as expected.

But obviously I want to do it in a single node so I'm not constrainting 
myself to the number of objects :-)

So I went into a rbdSpringConstraint and used $OBJNAME in the Object 
field of the anchorobjspacepos1 node.
And goal_`opdigits($OBJNAME)` in the Object field of the 
anchorobjspacepos2 node.

Appart from positions not jet propperly being set etc.. the main thing 
that goes wrong is that the $OBJNAME variable is not being used.
So all RBD object use a constraint between goal_0 and chunk_0.
I geuss the constraint1 node does know about which object is being 
processed but doesn't pass this upstream to the anchors.
If I connect.. my stream of objects... to an achorobjspacepos and use 
the same expression it actually does work in sense that it creates an 
anchor that's properly named goal for each RBD Object.
But in this way the anchor get's created in the root of the RBD Object 
instead of inside the Constraint.
I've also tried to create the Contraint first and then force the 
Anchor's Data Name to be 
But that creates a new branch with subfolder and looking at the icon 
they are of the type anchor.
Even tried Modify Data Dop..

Is this posible at all? The feeling I get from Dop's is that this should 
actually be easy... if you know what you're doing.


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