Pin Constraint

[JFWfilms]

Hi, 

 

I'm trying to get my head around constraints. I'm trying to create a pin constraint. I have constrained a box to a point that I created using the add node. I created a 'name' attribute for both the box and the point with piece0 as a string. Also on the point I have added another attribute with a 'position' constraint type. In the dop network I have a constraint network with a 'hard constraint relationship' as the input, It works when I use the point from the add node to constrain to, but if i switch it out for a packed primitive it doesn't work. is there a way that I can constrain an object to the position of another object. 

 

I'm new to Houdini so i'm not really sure what i'm talking about but hopefully that makes sense

 

Thanks!

 

Josh

[rich_lord]

Hi JFWFilms

 

I've attached a file with the simplest constraint networks in it so you can see how to set it up. Theres a packed primitive version, and the standard RBD object workflow.

 

The big difference is that in the packed prim version, the point attribute 'name' on the constraints should match the point attribute 'name' on the packed prim.

 

In the RBD object version, there is no name attribute on the RBD, so the name attribute on the constraint should be the name of the dop node itself.

 

Also, you dont really need the Add SOP. If a point in your constraint geometry has a blank name attribute, it will be constrained to the world.

 

Ive used spring constraints rather than pins becuase its quicker to see some motion.

 

Check out the file and let me know if you have any questions. This stuff is a little tricky at first, but its very simple once you understand it - and incredibly powerful.

[rich_lord]

oops, forgot to attach file, here it is.

constriant.hip