[cairo] Obtaining two parallel paths from a single curve
archee at 126.com
Tue Jul 29 07:14:58 PDT 2008
> archee at 126 (archee at 126.com) wrote:
>> Yes, it does work for a simple road. But what if you want to draw two
>> directions of a road? In that case, each direction is actually an independent
>> road but with the same shape.
> *If* the two directions are always parallel you could draw a wide line
> (maybe also using two strokes for an outline) plus a very thin line
> indicating the separation between the two directions.
> If this does not fit your problem: Unfortunately it is mathematically
> impossible to represent the parallel to a given bezier segment as a
> bezier segment, you have to resort back to approximations. There are
> solutions for this, you might find example code in inkscape.
In this way, you can not draw each direction of the road in different colors
(for example, to present traffic condition on each direction). So I think, to draw
these parallel curves, I need to do some mathematical calculation to get two different
curves according to the following knowledge:
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