Hi

I am wondering about the Resample SOP and the curveu attribute

In the example scene attached, a simple polygon and a Resample SOP.
When Treat Polygons is set to “Straight Edges”, curveu ranges from 0 to 1
But when Treat Polygons is set to “Subdivision Curves”, curveu ranges from 0 to 0.33

Does anyone know why and how to have curveu range from 0 to 1 even in Sudbivision mode?

Thanks
B

Looks like when you make subd curves with the resample sop curveu attribute will always be 1/number of points that aren't the first (0) point. I'm sure there's a technical reason why, someone else will have to weigh in on that. That said, it's pretty simple to normalize curveu, in a wrangle do @curveu = (float)@ptnum/(@numpt-1);

Hi,

it seems strange for me too. But if you evaluate the curve with primuv for example for the point attribute ‘P’, the range will be between 0 and 1. You don't have to evaluate ‘curveu’ attribute before. You can look at my example, just switch the uncomment lines (where float cu is defined) in the attribute wrangle to see the difference.

Hi

thanks for answering.

Yes the primuv() parameter ranges from 0 to 1.
But I am more after getting @curveu right for some other operation later on.

I know I can calculate it with the formula given by AndyW, but because I use the Resample SOP anyway I wanted to use this option (and it's also one node less to use).

And I did not realize it was depending on the number of points on the input curve.
This confuses me even more

I'll keep digging
Thanks

Hi,

it looks like a bug for me but I'm not sure. If you have a set of curves which are connected with increasing prim numbers (n-numbers) and every curve is (0,1) u-para, curve (i) can be reparametrize with (i,i+1) just subtracting the prim number (which is “i”) from the interval boundaries, so the whole curve is (0,n). Now if you want the whole curve (0,1) just divide by n so the first curve is (0,1/n) … the i-th will be (i/n,(i+1)/n), it is just an idea and I don't even thing it makes much sense here. You can avoid this anyway by just resampling the curve again but you need an extra node.

Hi all,
I‘ve just came across the same bug and contacted the sideFX Support.
They have logged it as a bug.
(ID# 86093)

Cheers, Michael

gotchee
I‘ve just came across the same bug and contacted the sideFX Support.
They have logged it as a bug.

Thanks! It should be fixed soon. The value was already in the “unit” domain in that case, and was being converted from “real” domain to “unit” domain unnecessarily, so it was easy to fix.

Hi all,

Good to know!
Thanks a lot, for reporting the bug and for fixing it.

Hi… if you evaluate the curve with primuv for example for the point attribute ‘P’, the range will be between 0 and 1. You don't have to evaluate ‘curveu’ attribute before. You can look at my example, just switch the uncomment lines in the attribute wrangle to see the difference.

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