Positions in curves?

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Bixelator Q

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Jun 12, 2023, 1:28:45 PM6/12/23
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Hi,

I'm trying to use I/OCurve classes for my application, but I'm confused about the positions (m_positions). 

Are they positions of control points (not necessarily on the curve) or curve points (on the curve)?  

Thanks,
Bella.

Lucas Miller

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Jun 12, 2023, 1:51:10 PM6/12/23
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I think they are control points based on how they are used in the Maya AbcImport plugin.

Lucas

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Nicholas Yue

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Jun 12, 2023, 2:12:12 PM6/12/23
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I believe they are control points base on the following
(2) RenderMan curves are spline based [https://rmanwiki.pixar.com/display/REN25/Curves]

HTH

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Bixelator Q

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Jun 12, 2023, 3:32:47 PM6/12/23
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Thank you for your insights! 
Then how about other attributes such as width (m_widths) and uvs (m_uvs)? I would assume they are also per control point. How would I get those values for curve points
if I'm tessellating the curve to line segments?

Bella

Lucas Miller

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Jun 12, 2023, 4:28:42 PM6/12/23
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Something to keep in mind about the widths is that it doesn't necessarily have to be per control point, it could be for all curves in that schema or even a single width per curve.

(Sadly I'm unsure about the interpolation math per your original question)

Lucas

Bixelator Q

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Jun 12, 2023, 11:44:46 PM6/12/23
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Thank you for the note! 
I might just try running De Boors on those attributes as well. 

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