[metapost] Re: new is_clockwise routine

Giuseppe Bilotta gip.bilotta at iol.it
Sun Nov 27 12:27:41 CET 2005

Sunday, November 27, 2005 Taco Hoekwater wrote:

> Werner LEMBERG wrote:
>>>Finding the direction at which a curve turns at any given
>>>point is easy: just find the sign of the cross product [...]
>> In my macros I use the cross product to check for grazing intersection
>> only.
>>>In general, to find the clockwiseness of a single Bézier
>>>cubics it suffices to check [...]
>> Far too complicated and slow to be implemented as macros IMHO.

> Put it looks like precisely the right way to fix the turningnumber
> primitive. Giuseppe, any chance of you writing some code for this?

Not within a short timeframe, I'm afraid. Writing MetaPost
macros isn't something I'm proficient in, so it takes quite
some time to get them right, and time is the last thing I
have plenty of in this end-of-PhD rush :)

I may be able to dedicate it some time from the second half
of the next month. It seems however that Paul Pichaureau is
looking. I'll be more than glad to check out any problems he
may come across (especially concerning METAPOST limitations)

Giuseppe "Oblomov" Bilotta

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