[pstricks] Automate a line drawing routine
Herbert Voss
Herbert.Voss at FU-Berlin.DE
Wed Dec 31 00:09:07 CET 2008
Michael Sharpe schrieb:
> I think there's a problem here that goes back to the code for
> \psIntersectionPoint, which gives a Postscript division by 0 error
> where the lines are parallel. This makes your macro fail when the line
> is either horizontal or vertical. (Try \psSlope(-4,2)(4,2).)
Michael,
this is not the problem with my example \psSlope(2,2)(4,1)
it is the negative slope, which needs the nodes sorted in another
order.
Herbert
> I think there needs to be a test in the code for the case where the
> absolute value of the determinant of dX1 dY1//dX2 dY2 is small--say, <.
> 01 times the area of ABCD, and in this case, the intersection could be
> declared to be 100 times the larger of (dX1,dY1), (dX2,dY2) plus the
> basepoint. The current code tests only for dX1 or dX2 small, which is
> not sufficient to prevent PostScript errors.
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