Parallel Face Selector

I have a definition that selects faces in the same direction-all left faces, all right faces, etc. Right now, it works if the faces are all orthogonal (first image), but goes haywire when the input faces are distorted (second). What is going on?

Surfaces in the second are a rhino cage edit of the surfaces in the first image. They were originally all closed polysrfs exploded just to input into grasshopper.

In the definition attached, each surface is compared to an original (its the small box in the far left of the top image) The point there is the ability to select for more than just the 6 faces of a cube, but find the closest match to more complicated inputs. In the second image, distorted surfaces are being compared to a distorted original.

If I have my math right, two parallel unitized normal vectors should have a dot product of 1, and the further away from 1 their dot product the further away from parallel, no? Why does it fail when I leave the comfy land of 90 degrees?

Attachments:

Parallel Face Selector.gh, 32 KB

Replies to This Discussion

Permalink Reply by Peter Stone on January 28, 2015 at 2:57pm

oops, size limits. Here is the rhino file of the distorted not working bit.

Attachments:

Test Parallel.3dm, 2.7 MB

Permalink Reply by Pieter Segeren on January 28, 2015 at 3:39pm

Hi Peter,
you have the wrong uv coordinates for the EvaluateSurface input. Try these methods:

Permalink Reply by Pieter Segeren on January 28, 2015 at 5:14pm

Hm, I took a closer look... ~ all planar surfaces, so the uv coordinates don't really matter:

Attachments:

ParallelFaceSelector_PSG.gh, 24 KB

Permalink Reply by Peter Stone on January 29, 2015 at 9:57am

Thanks! This is perfect- just needed to put the absolute value after the subtract component (otherwise it cant tell the difference between left and right)

Permalink Reply by Pieter Segeren on January 29, 2015 at 1:06pm

I figured you wanted that Peter, but than again - you wrote "parallel" ;)
Nice that you fixed my teaser:)

Permalink Reply by Peter Stone on January 29, 2015 at 1:13pm

Fair enough, naming things is not my strong suit. Thanks again!

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