Is there a way to join these curves into one primitive?

A Polygon curve can't split into two branches. At least not in Houdini. You can only have a single non-forking backbone.

You can use a Fuse SOP to consolidate the points of all the curves. This gives you no gaps but also leaves you with three primitives. Many tools in Houdini will work on the curves with consolidated points though.


In general the PolyPath SOP is used to take several curve segments and joint them into a single curve. The documentation for PolyPath also states that when it reaches a branch, that it will stop that curve and continue down each branch to join. Because your example has three curve segments, PolyPath SOP will not do anything as it assumes the result is valid from your input curves.

What do you want to do with the curves?

old_school
A Polygon curve can't split into two branches. At least not in Houdini. You can only have a single non-forking backbone.

You can use a Fuse SOP to consolidate the points of all the curves. This gives you no gaps but also leaves you with three primitives. Many tools in Houdini will work on the curves with consolidated points though.


In general the PolyPath SOP is used to take several curve segments and joint them into a single curve. The documentation for PolyPath also states that when it reaches a branch, that it will stop that curve and continue down each branch to join. Because your example has three curve segments, PolyPath SOP will not do anything as it assumes the result is valid from your input curves.

What do you want to do with the curves?

Thanks for responding Jeff, I wanted to use something like this in a Vellum Sim without having to constrain the points of the curves to each other. I did try the Fuse SOP and it didn't produce the result I was expecting but I think it was my fault. I used two Fuse SOPs (one for network in vellum geo and one for vellum hair constraint network because I was getting error that the geo and constraints had different number of points when I did the fuse before the vellum constraint SOP) But I now realize (after reading your post) that doing the one fuse was OK if I only put it in the geometry port of the vellum and not pass it into the constraints port because the constraint will get generated properly.