1. circle.e - Reply
Last night, when I saw Lucius' creation, I thought there must be a better way.
The routine below is based on a bastardized Bresenham's algorithm, but only
partially unrolled for speed.
There is not much point in adding inferior routines to our collection, but this
one, at least, has a tile option, missing from the Euphoria version.
It is adapted from my virtual screen set of routines, which includes virtual
pixels, lines and tiled rectangles, ellipses and polygons, as well as the basic
virtual screen manipulation routines. No assembly, just high level Euphoria
routines, but they compare surprisingly well with build-in routines in mode 19.
I shall release them as soon as I find some time to write a decent demo and some
docs. In the meantime, if anybody is desperate enough, just mail me. Jiri.
-- ellipse.ex ------------------------------------------------------------------
-- Jiri Babor
-- j.babor at gns.cri.nz
include graphics.e
include get.e -- wait_key()
object junk
sequence tile
procedure v_ellipse(object c,integer f,atom xc,atom yc,atom m,atom n)
-- c is color or 2d tile sequence, f is fill flag
-- xc,yc are centre coordinates, and m,n are major/minor radii
sequence s
integer x,y,dx,dy,r,rx,ry,xx,lx,ly,mx,my
xc=floor(xc)
yc=floor(yc)
m=floor(m)
n=floor(n)
dx=2*m*m
dy=2*n*n
r=m*n*n
rx=2*r
ry=0
x=m y=0
if not f then -- hollow ellipse
pixel(c,{xc-m,yc})
pixel(c,{xc+m,yc})
while x>0 do
if r>0 then
y=y+1
ry=ry+dx
r=r-ry
end if
if r<=0 then
x=x-1
rx=rx-dy
r=r+rx
end if
pixel(c,{xc-x,yc-y})
pixel(c,{xc+x,yc-y})
pixel(c,{xc-x,yc+y})
pixel(c,{xc+x,yc+y})
end while
elsif atom(c) then -- filled ellipse: single color
xx=m+m+1
s=repeat(c,m+m+1)
pixel(s,{xc-m,yc})
while x>0 do
if r>0 then
y=y+1
ry=ry+dx
r=r-ry
end if
if r<=0 then
x=x-1
xx=xx-2
rx=rx-dy
r=r+rx
end if
pixel(s[1..xx],{xc-x,yc-y})
pixel(s[1..xx],{xc-x,yc+y})
end while
else -- tiled ellipse
ly=length(c)
lx=length(c[1])
xx=m+m
y=0
s=c
for i=1 to ly do
while length(s[i])<xx+lx do s[i]=s[i]&c[i] end while
end for
mx=1+remainder(xc-x,lx)
my=1+remainder(yc-y,ly)
pixel(s[my][mx..mx+xx],{xc-x,yc})
while x>0 do
if r>0 then
y=y+1
ry=ry+dx
r=r-ry
end if
if r<=0 then
x=x-1
xx=xx-2
rx=rx-dy
r=r+rx
end if
mx=1+remainder(xc-x,lx)
my=1+remainder(yc-y,ly)
pixel(s[my][mx..mx+xx],{xc-x,yc-y})
my=1+remainder(yc+y,ly)
pixel(s[my][mx..mx+xx],{xc-x,yc+y})
end while
end if
end procedure
-- examples --------------------------------------------------------------------
junk=graphics_mode(19)
{9,14,14,14,9,9},{9,14,14,14,9,9}}
v_ellipse(tile,1,50,100,30,50)
v_ellipse(tile,1,200,100,100,50)
junk=wait_key()
junk=graphics_mode(-1)
