Anonymous user
Bitmap/Midpoint circle algorithm: Difference between revisions
Bitmap/Midpoint circle algorithm (view source)
Revision as of 00:03, 20 February 2009
, 15 years agofortran
No edit summary |
(fortran) |
||
Line 147:
6 6 5 blue test circle
test bshow cr
=={{header|Fortran}}==
This code should be inside <tt>RCImagePrimitive</tt> (see [[Bresenham's line algorithm#Fortran|here]]). The private subroutine <code>draw_circle_toch</code>, which writes to a ''channel'', is used by both <code>draw_circle_rgb</code> and <code>draw_circle_sc</code> and the interface allows to use <code>draw_circle</code> with ''[[Basic bitmap storage#Fortran|rgb]]'' images and [[Grayscale image#Fortran|grayscale images]].
<lang fortran> interface draw_circle
module procedure draw_circle_sc, draw_circle_rgb
end interface
private :: plot, draw_circle_toch</lang>
<lang fortran> subroutine plot(ch, p, v)
integer, dimension(:,:), intent(out) :: ch
type(point), intent(in) :: p
integer, intent(in) :: v
integer :: cx, cy
! I've kept the default 1-based array, but top-left corner pixel
! is labelled as (0,0).
cx = p%x + 1
cy = p%y + 1
if ( (cx > 0) .and. (cx <= ubound(ch,1)) .and. &
(cy > 0) .and. (cy <= ubound(ch,2)) ) then
ch(cx,cy) = v
end if
end subroutine plot
subroutine draw_circle_toch(ch, c, radius, v)
integer, dimension(:,:), intent(out) :: ch
type(point), intent(in) :: c
integer, intent(in) :: radius, v
integer :: f, ddf_x, ddf_y, x, y
f = 1 - radius
ddf_x = 0
ddf_y = -2 * radius
x = 0
y = radius
call plot(ch, point(c%x, c%y + radius), v)
call plot(ch, point(c%x, c%y - radius), v)
call plot(ch, point(c%x + radius, c%y), v)
call plot(ch, point(c%x - radius, c%y), v)
do while ( x < y )
if ( f >= 0 ) then
y = y - 1
ddf_y = ddf_y + 2
f = f + ddf_y
end if
x = x + 1
ddf_x = ddf_x + 2
f = f + ddf_x + 1
call plot(ch, point(c%x + x, c%y + y), v)
call plot(ch, point(c%x - x, c%y + y), v)
call plot(ch, point(c%x + x, c%y - y), v)
call plot(ch, point(c%x - x, c%y - y), v)
call plot(ch, point(c%x + y, c%y + x), v)
call plot(ch, point(c%x - y, c%y + x), v)
call plot(ch, point(c%x + y, c%y - x), v)
call plot(ch, point(c%x - y, c%y - x), v)
end do
end subroutine draw_circle_toch
subroutine draw_circle_rgb(img, c, radius, color)
type(rgbimage), intent(out) :: img
type(point), intent(in) :: c
integer, intent(in) :: radius
type(rgb), intent(in) :: color
call draw_circle_toch(img%red, c, radius, color%red)
call draw_circle_toch(img%green, c, radius, color%green)
call draw_circle_toch(img%blue, c, radius, color%blue)
end subroutine draw_circle_rgb
subroutine draw_circle_sc(img, c, radius, lum)
type(scimage), intent(out) :: img
type(point), intent(in) :: c
integer, intent(in) :: radius, lum
call draw_circle_toch(img%channel, c, radius, lum)
end subroutine draw_circle_sc</lang>
== {{Header|OCaml}} ==
| |||