1. Ellipse
- Posted by lithex <lithex at INTERGATE.BC.CA>
Sep 18, 1998
-
Last edited Sep 19, 1998
Hi
Here's an ellipse drawer that works at any angle and uses only
algebra and Euphoria.
Start of Euphoria code
-- This is a program that draws an ellipse
-- Written by Martin Hunt
-- This is a brute force approach, it examines each point on the
screen and -- determines whether it is on the ellipse or not. --
If it is on the ellipse, it makes a white dot, otherwise it
doesn't
include image.e
include get.e
include graphics.e
atom gr, sw, sh
sequence p1, p2, p3, p4, vidconf
gr=graphics_mode(18)
vidconf=video_config()
sw=vidconf[5] sh=vidconf[6]
p1={120,120} p2={210,200} p3={220,20} p4={150, 175}
function span_of(sequence p1, sequence p2)
return
(sqrt(power((p2[1]-p1[1]),2)+(power((p2[2]-p1[2]),2))))
end function
procedure Plot_if_on_ellipse(sequence foci, sequence point, atom k)
if floor(span_of(foci[1],point) + span_of(foci[2], point))=k
then pixel (WHITE, point) end if
end procedure
for i=1 to sw by 1 do
for j=1 to sh by 1 do
Plot_if_on_ellipse({p1,p2},{i,j},220)
Plot_if_on_ellipse({p2,p3},{i,j},230)
Plot_if_on_ellipse({p3,p4},{i,j},240)
Plot_if_on_ellipse({p4,p1},{i,j},250)
end for end for
End of Euphoria code
This is a brute force approach, and is a little slow.
The method just looks at every point on the screen, and sets it to
white if it is on the ellipse.
I'm trying to find a better method.
Bye
Martin
