1. Polygon bug?
Rob,
I have noticed that Euphoria's polygon routine has two small anomalies:
1. an unfilled polygon is often slightly different than the same polygon
outlined using the draw_line routine.
2. a complex filled polygon with a high number of vertices often produces
some spurious horizontal lines.
This happens in all the graphics modes that I have tried. Would this be a
bug in Euphoria or Watcom?
Colin
2. Re: Polygon bug?
Colin Taylor writes:
> I have noticed that Euphoria's polygon routine has
> two small anomalies:
If you can send me an example of each anomaly,
I'll look into it. It does sound more likely that this is
due to a bug, or bugs, in the WATCOM graphics library,
but I'd like to check it carefully.
Thanks,
Rob Craig
Rapid Deployment Software
http://www.RapidEuphoria.com
3. Re: Polygon bug?
Colin Taylor writes:
> I have noticed that Euphoria's polygon routine has
> two small anomalies:
Thanks for sending me the example program.
I can see the two effects that you are referring to.
> 1. an unfilled polygon is often slightly different than the
> same polygon outlined using the draw_line routine.
I'm not worried about this one. It seems to be clearly a case
where two different algorithms have been used to
compute the same thing, but in a few isolated instances the
numbers round off differently, and you see
a pixel plotted one position off from where it was plotted
with the other algorithm.
> 2. a complex filled polygon with a high number of vertices
> often produces some spurious horizontal lines.
This one is a bit harder to explain. Sometimes there's
a short line segment of several pixels that doesn't match
with the other algorithm. Maybe one algorithm, polygon(),
draws very sharp vertices as "invisible", while the other,
draw_line(), always draws a line segment. I'm not sure.
Anyway, thanks for reporting it. I don't think it will
cause a problem for the average person using polygon()
or draw_line().
Euphoria uses a different method for draw_line() than
it does for polygon(). Euphoria calls a WATCOM line-draw
routine for *each* draw_line() segment, but for polygon(),
it makes a single call to WATCOM's polygon routine.
Regards,
Rob Craig
Rapid Deployment Software
http://www.RapidEuphoria.com
