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Splines .. just a question - (#2427)
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jol  
#1 Posted : Sunday, June 28, 2009 9:44:49 AM(UTC)
jol

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Splines .. just a question - for somebody who uses another CAD

When I draw a spline, the end tangent is always zero .. ie: at the absolute end of the spline, the spline is straight (See A in attached image)

Do other CADs draw splines this way ?

.. or .. as I might expect, is there an option for the endpoints of the splines to have "free" tangency .. thus giving you the possibility of a default spline that does not flatten to the end (See B in attached image)
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jol  
#2 Posted : Sunday, June 28, 2009 9:54:04 AM(UTC)
jol

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.. and whilst on the subject .. I'd still like to have a default spline type that offers me all the benefits of an Interpolate Spline .. but with the ability to change not only the direction of the tangent, but also the length.

Without that tangent length control - you either need to start adding heaps of points you don't want or have to go to another spline type .. which then have other disadvantages

CDRS had wonderful splines this way - I wish we could offer this same ability !
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jol  
#3 Posted : Sunday, June 28, 2009 10:20:09 AM(UTC)
jol

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in short .. what I want is not 3 spline types which offer different benefits ..

.. but one default spline type which offers all the benefits of current interpolate and bezier splines (with points-on the spline)

Again - other CADs dont offer 3 spline types .. it's just confusing

how is it done in Rhino etc ?

we need one default Superspline !
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unique  
#4 Posted : Sunday, June 28, 2009 2:57:48 PM(UTC)
unique

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Originally Posted by: jol Go to Quoted Post

Again - other CADs dont offer 3 spline types .. it's just confusing

how is it done in Rhino etc ?


Yep it sure is...to the point where it's out of control even for development !!!

Rhino does a brilliant job with curves....no whistles and bells...:rolleyes:
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Tim Olson  
#5 Posted : Tuesday, June 30, 2009 1:02:12 AM(UTC)
Tim Olson

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>>When I draw a spline, the end tangent is always zero .. ie: at the absolute >>end of the spline, the spline is straight (See A in attached image)

Hi Jol

For interpolate splines ACIS defaults the curvature at the start/end to zero.

Unfortunately there are no options to control the magnitude of the start/end slope for an interpolate spline in ACIS.

With our available options to control the magnitude at the start/end of a curve you would need to use either a control point or bezier curve.

Tim
Tim Olson
IMSI Design/Encore
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