If it doesn't already exist, someone should make a masterclass on doing constraints and constraint like actions in Houdini. For the life of me, every time I go looking for information on doing a three point orientation constraint in SOPs, I get frustrated and give up.

Hi hibtachi,

I haven't come across the idea of a three point orientation constraint yet… what's the idea behind that?

Constraints, Rigging.. the whole thingamajig

Ha! Cool. I was mainly wondering about what the three point orient constraint was for, and what the problem could be

Maybe it is not a “thing” but what I call a constraint that needs three points to derive orientation, rotation, and transformation.

Usually I need it taking something moving and rotating, that I have to slap an emitter on. What I usually come across is someone trying to tell me I can do it at object level. I'd like to know how to do it in SOPs. I'm assuming it's through some expression work or VOP/Wrangle nodes.

Hmm, it's really hard to know what exactly you're after without an example, but it's well worth taking a look at the lookat() function in VEX, it calculates the same things as a obj level lookat constraint but returns a transform matrix instead that you can use to modify the position or other attribute.

Hope that's useful

Check out the Constraints shelf. I used the LookAt and Points tools to make this scene, though I had to setup a point group on the torus, and fiddle with the Point Constrain Look At / Look Up (see /obj/teapot/constraints/points). Hopefully this little example helps a bit. Check out the the constraints chop networks inside the torus and sphere objects to see what those shelf tools create.

There are some rigging masterclasses in the works by SideFX, which will be excellent.

This may be what your looking for…

http://www.tokeru.com/cgwiki/?title=HoudiniVex [tokeru.com]

just scroll down page where it starts with “Get transform of objects with optransform”.

BabaJ That is the kinda stuff I'm talking about.

I appreciate all the suggestions everyone.

I've a hard time understanding how to use and setup constraints and constraint networks as well. The documentation doesn't really help since it doesn't give a good overview and no use cases. An answer like “The Constraint Object Pretransform CHOP returns an Object pretransform.” about the question “What is a Constraint Object Pretransform?” doesn't help me as a beginner at all.

Did you try searching for ‘Pretransform’?

http://www.sidefx.com/docs/houdini/basics/objects#pretransform [www.sidefx.com]

The Rivet object is another (old-school) option.