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Transitioning from NURBs

Lately I’ve been getting deeper into Modo from Luxology. It’s a poly and subdivision surface modeler (as well as animation and rendering engine) which is great, but I really liked working with the NURBS in Studio Tools and Maya. For some things it’s easier just to lay out curves and sweep the surfaces, at least for me. While Modo doesn’t have NURBs, it does allow you to do some of the same kind of modeling using curves and Patch Curves tools. This is where you find the Patch Curves tool. It’s the same button used for the other Curves.

The Hitch:

If you follow the otherwise great help system, it does tell you how to create the Patch. However, it leaves out one really important step that you have to do otherwise it doesn’t work. I’d lay out four curves, snap the vertices to each other, then try to run the Patch. No such luck. You can extend the curves on the ends for some cool effects, but no surface like you’d get using a Boundary or Square in Alias.

The Fix:

It’s really dead simple: just merge the vertices with the (appropriately named) Merge Tool. You’ll find it under the vertex tab:

Didn’t know I had to do that, but it does make sense. Once the verts are merged, all the curves are happy, and the patch tool works like a champ.

To illustrate, here are some curves and the resulting patch:

Then you run the Merge Tool and apply it. The default values should be OK as long as you’ve either snapped to the vert or the grid when you created the curve. The go back to the basic tools tab and select the Patch Curve tool. Set the tool mode to “Define Patch”, then click in the view port. Then select each curve and you’re done!