Henry Dean

friedasparagus

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My Tutorials

obj-image Intermediate
Rigging with CHOPs - 2 (with added foot roll)
obj-image Intermediate
Rigging with CHOPs - 1

Recent Forum Posts

How to get object worldspace xform after constraints/chops May 25, 2018, 8:51 a.m.

Hey,

This isn't very clear from the docs, so I wouldn't beat yourself up

The Get World Space CHOP grabs what Houdini calls the ‘preconstraint transform’. The first input in most CHOP constraint setups will be this node pointing to the object being constrained (with the relative path “../..”). This prevents recursion problems.

In your case you'll be wanting to use the node listed as ‘Object (Constraints)’ under the network editor tab menu. This one fetches the final (post-constraint) world transform of the object, or the final relative transform to the node pointed to in the ‘Reference’ parameter (leave this blank for World Transform).

Be wary of recursion problems if you get too involved in intercepting/rebuilding transform hierarchies through constraints… Even though the ‘Get World Space’ chop node grabs the pre-constraint transform of the target object, that pre-constraint transform still contains any post-constraint transforms that are present in its parents. So attempting to set constraints on a parent object based upon a child object's preconstraint transform will still result in ‘infinite recursion’ errors.

It's more than likely you can ignore that last paragraph as it's something that generally only happens when you try something daft (as I have done many, many times)

storing @P to @mypos doesn't work May 20, 2018, 10:46 a.m.

Hi Olivier,

apart from a small list of reserved attribute names (like @P and @N) you need to tell houdini what type the attribute is. Replacing @mypos with v@mypos should fix things

boneCapture_pCaptData Row Order confusion May 16, 2018, 1:15 p.m.

Ha… quite right, quite right I meant to be more emphatic, as in ‘have I missed something really obvious?’

EDIT: As it turns out, yes I was missing something really obvious - the alignment of the cregion… which is itself a child transform. And as the matrix represents the cregion transform, not the bone, the default z-axis alignment would produce the matrix in the attribute… I'm going to sleep now and hope that I wake up with my brain screwed in