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Full Version: Cutting template for frustum

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From: gunter511
27 Dec 2017   [#22]
Thank you ALL for your help. Your support is really invaluable :)

Happy New Year!
Gunter
From: bemfarmer
27 Dec 2017   [#23] In reply to [#21]
Thank you Karsten.

My understanding of Isocurves, UV, and NURBS is improving, but more study is needed :-)

- Brian
From: Karsten (KMRQUS)
27 Dec 2017   [#24] In reply to [#23]
Hello Brian,

there is no deeper understanding needed. If you want, start with the simplest form of a curve - a line with start and end point (P0,P1). You can describe every point of the curve by a parameter u in this form: Pm(u)=(1-u)*P0+u*P1 with 1-u;u as weight/blending functions. The sum of both is always 1.

Now take a second line with P2,P3
Pn(u)=(1-u)*P2+u*P3

Now create a line between the curves with a parameter v:

PS(u,v)=(1-v)*Pm(u)+v*Pn(u)

This describes a ruled surface, better a point on it.
If one parameter is constant and the other is variable, you describe a iso curve. If you use more points and want to use Bezier have a look to Bernstein polynoms ---- 1-u;u are basic ones. If you want to use other e.g. spline you have to use different ones.

Have a nice day
Karsten
p.s.: No magic, nothing mystic - very simple vector math, but some of the guys try to give it a special flavour with mystic math symbols!

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