1. Re: xor_line
Sorry, Hawke, I should not rely on my memory that much, it's like a
sieve. I just checked the archive version of rat.e, and you are right,
the xor library is not there. I completely forgot I had not released
the complete widget set with the ratpack, just a cut-down version, in
other words only the routines necessary for the demo (I think, Irv had
already been pushing his 'windoz', and I did not want to create unfair
competition).
If you still want to compare notes, or for anybody else possibly
interested, the routine is attached below.
Sorry again, but I told you to give me a yell, if you strike a
problem..
jiri
global procedure xor_line(integer c, sequence p)
-- c is line color - same usage as draw_line, but limited
-- to single line segment between 2 points in sequence p
integer ai,bi,d,x,y,x2,y2,xi,yi,dx,dy
p=floor(p)
x=p[1][1]
x2=p[2][1]
y=p[1][2]
y2=p[2][2]
if y=y2 then -- horizontal line
if x<x2 then
pixel(xor_bits(get_pixel({x,y,x2-x+1}),repeat(c,x2-x+1)),{x,y})
else
end if
elsif x=x2 then -- vertical line
if y<y2 then
for i=y to y2 do
pixel(xor_bits(get_pixel({x,i}),c),{x,i})
end for
else
for i=y2 to y do
pixel(xor_bits(get_pixel({x,i}),c),{x,i})
end for
end if
else
if x<x2 then
xi=1
dx=x2-x
else
xi=-1
dx=x-x2
end if
if y<y2 then
yi=1
dy=y2-y
else
yi=-1
dy=y-y2
end if
pixel(xor_bits(get_pixel({x,y}),c),{x,y})
if dx>dy then
ai=2*(dy-dx)
bi=2*dy
d=bi-dx
while x!=x2 do
if d>=0 then
y=y+yi
d=d+ai
else
d=d+bi
end if
x=x+xi
pixel(xor_bits(get_pixel({x,y}),c),{x,y})
end while
else
ai=2*(dx-dy)
bi=2*dx
d=bi-dy
while y!=y2 do
if d>=0 then
x=x+xi
d=d+ai
else
d=d+bi
end if
y=y+yi
pixel(xor_bits(get_pixel({x,y}),c),{x,y})
end while
end if
end if
end procedure -- xor_line
global procedure xor_draw_line(integer c, sequence p)
-- same usage as draw_line: c is line color, p is sequence of
-- points ({x,y} coordinates) to be connected
-- works ok for single line segments, but xor_line() above is faster
for i=1 to length(p)-1 do xor_line(c,p[i..i+1]) end for
-- compensate for cancellations at line joints
for i=2 to length(p)-1 do pixel(xor_bits(get_pixel(p[i]),c),p[i]) end
for
-- compensate for cancellation at closure for line loops
if not compare(p[1],p[length(p)]) then
pixel(xor_bits(get_pixel(p[1]),c),p[1])
end if
end procedure
-----Original Message-----
From: Hawke <mdeland at NWINFO.NET>
To: EUPHORIA at LISTSERV.MUOHIO.EDU <EUPHORIA at LISTSERV.MUOHIO.EDU>
Date: Sunday, October 25, 1998 3:03 PM
Subject: Re: truecolr.e update, line(), other stuff...
>jiri babor wrote:
>>Go to the Archives and fetch my ratpack (SVGA mouse routines).
>>In it you will find a little library called xor.e.
>>From memory, among other graphic elements it also contains
>>an xor_line routine.
>ummm... i looked all thru all the files in rat.zip and i
>couldn't find xor_line. i looked pretty thoroughly...
>
>>It is based on Bresenham's line algorithm,
>knowing this however, i was able to find that algorithm
>and implement it (it's pretty quick),
>so thankee! for the tip... :)
>
>--Hawke'
>
