Monday, September 20, 2010

My First Rhinoceros 3D tool!

Rhinoceros 4's symmetric feature left much to be desired. Essentially a forced build session with history mirroring on the Z coordinate, I didn't like how inflexible it was compared to what I was hoping for...so, I decided to write a better one. It was, I thought, a simple enough function to get acquainted with both Rhino's scripting environment and ramp up on VBA.

Boy was I wrong, VBA is a pain in the *@#$ to work with, and Nurb objects are a lot more complicated than I had thought. With VBA and loop matrices foibles, and Nurb object minutia mastered, my first tool started to take shape nicely. I've named it "Surface Lateral Symmetry" and it does as advertised...mostly. Rough to be sure, but it does work.

Another reason for building this tool along with my disliking the official implementation of surface symmetry is that I like rebuilding surfaces as a sculpting technique. But as I found, Rhino has a bad habit of mangling symmetry on certain rebuilds. This asymmetry was not only unexpected, but it is difficult to detect because the grips that are misaligned can be off by mere hundredths of a Rhino unit but will then wreak havoc down the production line. Most avoid this by slicing objects down the median then dealing with that seam but this I've found can lead to many headaches with surface blends, fillets and chamfers misbehaving. So, with my tool, I can avoid down stream mismatches as well as obviate much headaches from visible seam glitches.

Below is an example of the tool in action.

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