UV frame directions... What am I missing?

I put this in grasshopper as it´s my concern, but I guess my question is deeper. Feel like a noob…
Why are the UV frames not aligned/tangent to U or V lines? I get they couldn’t be aligned to both at the same time, but to none?

One of the frame axis is aligned with the U or V at the frame origin here as shown. Let me know if I’m misunderstanding your question though and I’ll make sure it’s not a bug that needs filing.

FrameAlignmentOnSrf.gh (14.7 KB)

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Thanks Brian!

I see now. I have difficulties predicting UV orientation on my surfaces (usually lack of attention).
My question after your reply… Could it be possible to choose the alignment? Is it arbitrary or has a deeper reason? As you point the frames are aligned with one direction but I needed just the other. To achieve this I had to get the “other direction” isolines and use them as frame axis… Clumsy workaround of mine as usually, but it worked.

I think you could add an Align Plane component like this…

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I’m pretty sure the plane X-axis is parallel to the U direction, and the Y-axis is then picked to have the correct orientation, regardless of the actual V direction.

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A coherent rule. My problem/question arises when willing to get the other direction. Shouldn’t it be possible to toggle it without workarounds like @BrianJ’s or mine?

Yeah would be nice to have options that allow for U->X, V->Y or Average alignment. This would have to be added to at least [Evaluate Surface] and [Surface Frames]. Or maybe add another component which provides the exact U and V directions as separate vectors at a Surface (u,v) coordinate.

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I added a new [Evaluate Surface] component which includes U and V output vectors. (The old one is now obsolete, though still available when loading existing gh files of course.)

It seemed like the least amount of disruption for the most amount of flexibility and consistency. Using those vectors you can create whatever plane you’re looking for relatively easily.

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Did you “just” add that component (cause I can´t find it in RH6 GH), @DavidRutten? If so, you guys are IMPRESSIVELY AWESOME!

Yeah, “just” before I wrote that. It should be in the next weekly WIP release.

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