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hanhphuc

SPLINE Fit points missing

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hanhphuc

hi all, can ACAD newer version replicate this bug? (2007)

 

0. draw a SPLINE

1 SPLFRAME sets to

2.manually to modify / shift Control Points from its original positions

3.SPLFRAME sets to 0

4.REGEN, why Fit points grips get toggled off!?

system variables issue?

 

version - Bugs

2007 - Fitpoints gone

2008 - ??

2009 - ??

2010 - ??

...

...

2017 - ??

2018 - ??

 

 

spl bug.gif

Edited by hanhphuc
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lrm

Non-Uniform Rational B-Splines (NURBS) are represented as a series of Control Vertices (CVs) that have associated weights for each CV.  When you create a spline with Fit points the AutoCAD spline software calculates a set of CVs that will yield a spline that passes through the CVs. Note that for a given set of Fit points there are an infinite variety of smooth curves that could pass through the points.  The spline software uses some rules that create a “reasonable” curve.  The Fit points near a CV lose their meaning if the CV near them is moved resulting in relocated fit points.   You should consider that the definition of a spline is based primarily on its CVs and that the Fit points are secondary to them.  Perhaps the frame and CVs are turned off when you change to the Fit point method of editing to reduce confusion between the two sets of points and to highlight the fit points which are usually of more concern to a designer. 

 

With 2018 you can turn on the spline frame display (which I prefer to do via properties) but must explicitly note whether you want to edit Fit points or CVs.  The frame is hidden if the method is changed to Fit. Note that you can move fit points and dynamically see the change in CV location if the CV Frame is shown.

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hanhphuc
10 hours ago, lrm said:

 

With 2018 you can turn on the spline frame display (which I prefer to do via properties) but must explicitly note whether you want to edit Fit points or CVs.  The frame is hidden if the method is changed to Fit. Note that you can move fit points and dynamically see the change in CV location if the CV Frame is shown.

 

Thank you sir for the input. oh It looks like 2018 already  has improvement to switch Fit points ON.

so i think that is version issue. i'll try research any system variable or activeX methods to revert fit points in v2007

 

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