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## [help-3dldf] Re: new is_clockwise routine

**From**: |
Laurence Finston |

**Subject**: |
[help-3dldf] Re: new is_clockwise routine |

**Date**: |
Sun, 27 Nov 2005 13:32:29 +0100 (MET) |

On Sun, 27 Nov 2005, Werner LEMBERG wrote:
>* I thought that the idea of my code is quite obvious, but apparently it*
>* isn't. Here's the used algorithm.*
I don't usually find reading other people's code enjoyable. Thank you for
the explanation in plain English.
>
>* 1. Find a point P on the path which has a non-zero direction.*
[...]
>* This method completely avoids any problems with the geometry of Bézier*
>* curves.*
It seems like a roundabout way of doing it, which is the impression I had
before. You asked for comments, so I explained how I plan to go about
it, if and when I reach this point. If it's not helpful to you, please
disregard it. I don't see any problems with the geometry of Bezier
curves. One can convert the representation using control points into a
polynomial and manipulate the latter using straightforward and
well-documented methods.
>* > A more serious problem is determining whether the curve loops or*
>* > changes direction between two values of 't'.*
>
>* As mentioned in my last mail, I assume that the curve doesn't*
>* intersect itself. It's not needed for my particular problem, and it*
>* makes life much simpler.*
I try to find general solutions without losing touch with reality.
Laurence