I haven’t used gh in a while now. Back to it briefly for some office furnishing schematics. One of the things that always drove me nuts about gh is the need for extensive “error” reconciling when modifying base geometry–in this case, a simple gh-generated 2-pt box–an excellent primitive example. What I mean is, just because an initial result came out one way/direction, doesn’t mean it’ll come out that way again (like when adjusting an earlier parameter (e.g.height)), which still tends to fall on the “incomprehensible” spectrum for me–could be my lack of CompSci, but seems like an order-of-things issue… Anyway, here’s the description
Issue: UV directions of face/surface flip depending on the height of the originating 2-point box. (At least face0 is always face0, relative to world-plane.)
Description: When box height = 40", U direction is vertical (horizontal divisions); when box height = 41", U direction is horizontal (vertical divisions). Issue exists for other ‘Z’ values, too.
Expectation:
UV direction is based on some predictable formal quality, and does not flip (randomly) unless the formal quality is seriously altered, similar to predictable vertex numbering order, etc., perhaps based upon proportion or something (U is always the longer side, etc).
Steps (all in Grasshopper):
- Use gh ‘Construct Point’ to supply ‘Box 2Pt’ w/ A & B point values
- Extract a desired face using ‘DeBrep’
- Subdivide surface (various techniques) & select output to preview/highlight
- Using a slider, adjust the Z value of point B
Notes:
Various surface division techniques will flip UV on diff Z values, but they all seem to flip at some point;
Doesn’t seem to be predicated upon box/face proportion (e.g. small-Z or big-Z relative to XY area).;
Can’t predict which values will flip it (w/o differential calculus, anyway!).
File:
Box-UV flip.gh (25.8 KB)
Please advise, and thanks in advance,
-dt
