In the houdini help there's a section on exporting simulation data to other networks.

You can pull out any type of geometry data from a simulation, including not just the final simulated geometry, but also collision fields, visualizations, and guide geometry. Look in the details view to see what data is available on a given object.

I tried looking in the details view to pull the pin contstraint lines from the Dynamics
pendulum example into a geo via an object_merge. I can grab the simulated pendulums
but not the lines that connect them.. which id like to do..

anyone know how to do this?
thanks.

I believe the guide geometry for the constraints is being built in OpenGL and has no representative data in the simuation data.

I created a file that contains an HDA that builds the link from a pin constraint by typing in the path to the sim and the name of the constraint.

Awesome! Thanks for the quick response!

Hey Jeff, trying to extend this for a second constraint, and could use some input.
if you check out the pendulum example there is a pin_upper_pendulum constraint
for which this works great.. but then there is a pin_pendulums_together constraint
which connects a secondary pendulum to the first for which this doesnt work
so great. any input? mucho gracias!

oh and there are a bunch of chop nodes like null and rename
that have an export prefix as /obj. Is this necessary or just
a default? It generates a bunch of otl parameter warnings
that a reference is being made outside of the hda. Ill try
getting rid of it and see what happens.

yeah, all chop nodes appear to have a common tab with and export prefix
set to /obj (by default). The operator type manager complains about all of
these when trying to save the hda.. a bug perhaps?

Im poking around with adding a point for the GoalAnchor of
the secondary constraint without much success.. the result
is still evaluates to z=0 and y=0…

sdugaro
yeah, all chop nodes appear to have a common tab with and export prefix
set to /obj (by default). The operator type manager complains about all of
these when trying to save the hda.. a bug perhaps?

it's not a bug.
when rigging characters as HDAs I always delete the Export Prefix on the Common Tab…never had any problems.

goldfarb! how u doin brother? whats up @ c.o.r.e?
go see cloudy with a chance of meatballs. I dont think
an animated feature has ever made me laugh so hard
since the first storyboards of the wild.

ok, since it doesnt look like theres an immediate way to get constraint geometry
ive instead added 3 points (the origin, the centroid of the first pendulum, and
the centroid of the 2nd pendulum) delete all points but the centroid, merge
them together in the order i want and use another add sop after the merge
to create the lines i need, with a final polywire to get some renderable geom
for the constraints..

This HDA is wicked however… and with a little effort i think it can be tweaked
to lookup and use the worldspacepos and offset of the CurrentAnchor
and GoalAnchor from the Relationships folder of the Dop Network.