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 CAD / MLCad / 1524
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Subject: 
Re: *** Start celebrating .... NOW
Newsgroups: 
lugnet.cad.mlcad
Date: 
Fri, 27 Dec 2002 23:31:58 GMT
Viewed: 
4776 times
  
In lugnet.cad.mlcad, Orion Pobursky writes:

I think the most confusing aspect of the existing curve program, with the
exception of Fredrik's, is the fact that the control points are tricky to
position correctly.  Fredriik's LDraw mode solves this by dynamically
determining the control points.

If memory serves me well, in Fredrik's Ldraw mode you specified the
endpoints in terms of orientation as well as coordinates, stated the number
of joints and it calculated the rest. Certainly a good system for many
instances as that information is often easily derived from the attachment
points in the model itself.

I tried the Bezier curve generator and it seems pretty logical, however,
when I feed the values back into the MLCad hose generator it doesn't seem to
generate the same curve. Perhaps it is using another method, or perhaps I am
still missing something obvious? :-) Another thing that I don't understand
is how the elements in the hose are not evenly distributed along its length.

Jennifer



Message has 2 Replies:
  Re: *** Start celebrating .... NOW
 
(...) Some progress - myself and a CAD expert mucked about a bit until we realised the obvious thing I was missing, the fact that the control point coordinates are specified relative to the end points and not in absolute coordinates! Jennifer (22 years ago, 28-Dec-02, to lugnet.cad.mlcad)
  Re: *** Start celebrating .... NOW
 
(...) This sounds like a shortcut in the algorithm. If the bezier function is f(t), it does not have the property that |f(t) - f(t+d)| = c for all t, d given. I've corrected for this in my algorithm by using some simple optimization to find a (...) (22 years ago, 28-Dec-02, to lugnet.cad.mlcad)

Message is in Reply To:
  Re: *** Start celebrating .... NOW
 
(...) I think the most confusing aspect of the existing curve program, with the exception of Fredrik's, is the fact that the control points are tricky to position correctly. Fredriik's LDraw mode solves this by dynamically determining the control (...) (22 years ago, 27-Dec-02, to lugnet.cad.mlcad)

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