graphics-bug

[CarlManning@ai.mit.edu (Carl R. Manning)]

    Date: Fri, 30 Nov 90 15:26+0100
    From: gmdzi!nieters%sphinx@ai.sri.com (Hans Nieters)

    The call of draw-polygon does not produce visible output in case of thickness 1
            for skew lines in genera-8

    (graphics::draw-polygon  '(100 100 100 200 300 200 200 100) :thickness 1 :filled nil)

    Since it works for genera 7, i am surprised. Can it be repaired?

    Hans Nieters  

Use :thickness 0, which in the new graphics substrate of Genera 8 is the
'device minimum' rather than 'exact' thickness.  Using thickness 1 is supposed
to give you exactly displayed lines, which may not be possible at all angles.

My theory about why thickness 1 'shouldn't' work:  If you assume square pixels,
then the width of a non-vertical or horizontal line is greater than the
horizontal or vertical width of a pixel; for a 45 degree angle line, the width
of the line might be interpreted as (sqrt 2) pixels.

-- CarlManning@ai.mit.edu