287 lines
8.4 KiB
Fortran
287 lines
8.4 KiB
Fortran
!-----------------------------------------------------------------------
|
|
!-
|
|
! some functions for the project "gravity field"
|
|
!-
|
|
!-----------------------------------------------------------------------
|
|
module realfield
|
|
use spitpgm ! XXX
|
|
|
|
implicit none
|
|
|
|
!-----------------------------------------------------------------------
|
|
!-
|
|
! definition of structures
|
|
!-
|
|
type massbody
|
|
real :: posx = 0, posy = 0
|
|
real :: heading = 0.29
|
|
real :: speed = 1.017
|
|
real :: mass = 1.0
|
|
integer :: serial = 666
|
|
end type
|
|
|
|
!-----------------------------------------------------------------------
|
|
contains
|
|
!-----------------------------------------------------------------------
|
|
subroutine compute_barycentre_bodies(astres, bcx, bcy)
|
|
type(massbody), intent(in) :: astres(:)
|
|
real, intent(out) :: bcx, bcy
|
|
integer :: foo
|
|
real :: cx, cy
|
|
|
|
! May be we have to use DOUBLE RPECSION here ?
|
|
cx = 0.0
|
|
cy = 0.0
|
|
do foo=1, ubound(astres, 1)
|
|
cx = cx + astres(foo)%posx
|
|
cy = cy + astres(foo)%posy
|
|
enddo
|
|
bcx = cx / real(ubound(astres, 1))
|
|
bcy = cy / real(ubound(astres, 1))
|
|
end subroutine
|
|
!-----------------------------------------------------------------------
|
|
subroutine print_barycentre_bodies(astres)
|
|
type(massbody), intent(in) :: astres(:)
|
|
real :: cx, cy
|
|
|
|
call compute_barycentre_bodies(astres, cx, cy)
|
|
print *, "barycentre : ", cx, cy
|
|
|
|
end subroutine
|
|
!-----------------------------------------------------------------------
|
|
!-
|
|
! make a few solid body to play with...
|
|
!-
|
|
! planets : an array of type(massbody) to be filled
|
|
! coef : for setting the mass of the body
|
|
! sx, sy : borders of the universe
|
|
!-
|
|
subroutine create_some_planets(planets, coef, sx, sy)
|
|
type(massbody), intent(inout) :: planets(:)
|
|
real, intent(in) :: coef
|
|
integer, intent(in) :: sx, sy
|
|
integer :: foo
|
|
character(100) :: fmt
|
|
|
|
fmt = "(I4, ' | ', 2(F10.2, ' '), ' | ', 2F9.3, ' ', e12.3, I7)"
|
|
|
|
do foo=1, ubound(planets, 1)
|
|
if (foo .EQ. 1) then
|
|
!-
|
|
! the first planet is the home of Johnny Root
|
|
!-
|
|
planets(1)%posx = sx / 2
|
|
planets(1)%posy = sy / 2
|
|
planets(1)%mass = 31e8
|
|
planets(1)%serial = 1337
|
|
planets(1)%speed = 6.666
|
|
else
|
|
!-
|
|
! others are planets for peones
|
|
!-
|
|
planets(foo)%posx = rand() * real(sx-1)
|
|
planets(foo)%posy = rand() * real(sy-1)
|
|
planets(foo)%mass = 7e6 + coef*foo
|
|
planets(foo)%heading = 2 * 3.14159 * rand()
|
|
if (rand() .LT. 0.15) planets(foo)%speed = 3.14159
|
|
planets(foo)%serial = foo*2 + 120
|
|
endif
|
|
|
|
write (*, fmt) foo, planets(foo)
|
|
enddo
|
|
end subroutine
|
|
!-----------------------------------------------------------------------
|
|
!-
|
|
! the basis of the kluge
|
|
!-
|
|
function compute_gravity(fx, fy, body)
|
|
real, intent(in) :: fx, fy
|
|
type(massbody), intent(in) :: body
|
|
real :: compute_gravity
|
|
real :: rx, ry, dist
|
|
|
|
rx = fx - body%posx
|
|
ry = fy - body%posy
|
|
dist = sqrt( (rx*rx) + (ry*ry) )
|
|
if (dist .LT. 0.08) then
|
|
! write (0, *) "dist too small ", dist
|
|
compute_gravity = 0e0
|
|
else
|
|
compute_gravity = body%mass / (dist ** 2)
|
|
endif
|
|
|
|
end function
|
|
!-----------------------------------------------------------------------
|
|
!-
|
|
! Export a massbody area to a text file. no error check, wtf ?
|
|
!-
|
|
subroutine save_bodies_to_txt_file (astres, fname)
|
|
type(massbody), intent(in) :: astres(:)
|
|
character(len=*), intent(in) :: fname
|
|
|
|
character(50) :: fmt
|
|
integer :: io, idx
|
|
|
|
write(0, "('saving planets to ', A20)") fname
|
|
fmt = "( 2(F9.3, ' ') 2(F9.3, ' '), F14.3, I8)"
|
|
open(newunit=io, file=fname)
|
|
do idx = 1, ubound(astres, 1)
|
|
write(io, fmt) astres(idx)
|
|
enddo
|
|
close(io)
|
|
end subroutine
|
|
!-----------------------------------------------------------------------
|
|
!-
|
|
! Compute the gravity field in a pre-allocated array relative
|
|
! to the massbody 'moon'. Nobody know where the magic numbers
|
|
! come from, sorry.
|
|
!-
|
|
subroutine compute_a_field(field, moon)
|
|
real, dimension(:,:), intent(out) :: field
|
|
type(massbody), intent(in) :: moon
|
|
|
|
integer :: ix, iy
|
|
real :: fx, fy
|
|
real :: grav
|
|
|
|
! print *, "pic size ", ubound(field, 1), "W", ubound(field, 2), "H"
|
|
! print *, "mass body ", moon
|
|
|
|
do ix=1, ubound(field, 1)
|
|
fx = real(ix)
|
|
do iy=1, ubound(field, 2)
|
|
fy = real(iy)
|
|
grav = compute_gravity(fx, fy, moon)
|
|
field(ix,iy) = grav
|
|
enddo
|
|
enddo
|
|
|
|
end subroutine
|
|
!-----------------------------------------------------------------------
|
|
!-
|
|
! compute a field with only one body; and write a pic file
|
|
!-
|
|
subroutine build_and_write_a_field(szx, szy, moons, fname)
|
|
integer, intent(in) :: szx, szy
|
|
type(massbody), intent(in) :: moons(:)
|
|
character(len=*), intent(in) :: fname
|
|
|
|
real :: maxi, mini
|
|
integer :: errcode, foo
|
|
real, dimension(:,:), allocatable :: field, tmpf
|
|
integer, dimension(:,:), allocatable :: greymap
|
|
|
|
allocate(field(szx, szy), stat=errcode)
|
|
allocate(tmpf(szx, szy), stat=errcode)
|
|
|
|
field = 0.0
|
|
do foo=1, ubound(moons, 1)
|
|
call compute_a_field(tmpf, moons(foo))
|
|
tmpf = tmpf * 0.018
|
|
field = field + tmpf
|
|
enddo
|
|
|
|
maxi = maxval(field)
|
|
mini = minval(field)
|
|
! print *, "field: ", mini, maxi, maxi-mini
|
|
|
|
allocate(greymap(szx, szy), stat=errcode)
|
|
greymap = 65533
|
|
! convert from real value to 16 bits int values
|
|
where (field < 65530.0)
|
|
greymap = int(field)
|
|
end where
|
|
|
|
call spit_as_pgm_16(greymap, trim(fname))
|
|
|
|
! make valgrind happy
|
|
deallocate(field)
|
|
deallocate(greymap)
|
|
|
|
end subroutine
|
|
|
|
!-----------------------------------------------------------------------
|
|
!-
|
|
! Yes, I know, this is a disturbing kluge, but I like it :}
|
|
! May be, it's time to read the doc of modern Fortran
|
|
!-
|
|
subroutine init_random()
|
|
|
|
integer, dimension(3) :: tarray
|
|
integer :: t3
|
|
real :: dummy
|
|
call itime(tarray)
|
|
t3 = 8971*tarray(1) + 443*tarray(2) + tarray(3)
|
|
write(0, '(A,3I3,A,I6)') "sranding: ", tarray, " --> ", t3
|
|
call srand(t3)
|
|
! after initializing the random generator engine,
|
|
! you MUST use it for initializing the initializer
|
|
do t3=1, 4
|
|
dummy = rand()
|
|
write(0, '(" dummy", I4, F9.6)') t3, dummy
|
|
enddo
|
|
|
|
end subroutine
|
|
!-----------------------------------------------------------------------
|
|
!-
|
|
! dump a field of reals numbers to disk - preliminary version
|
|
!-
|
|
subroutine dump_a_field_to_file(field, fname)
|
|
real, dimension(:,:), intent(in) :: field
|
|
character(len=*), intent(in) :: fname
|
|
|
|
integer :: header(8)
|
|
integer :: io
|
|
|
|
print *, "D) field size ", ubound(field, 1), "W", ubound(field, 2), "H"
|
|
print *, "D) filename ", fname
|
|
|
|
header = 0
|
|
header(1) = 574908040 ! magic number
|
|
header(2) = 1 ! this is a dump of real field
|
|
header(3) = ubound(field, 1)
|
|
header(4) = ubound(field, 2)
|
|
header(5) = 666
|
|
|
|
open(newunit=io, file=fname, form='unformatted')
|
|
|
|
write(io) header
|
|
write(io) field
|
|
|
|
close(io)
|
|
|
|
end subroutine
|
|
!-----------------------------------------------------------------------
|
|
!-
|
|
! load a real field from file - preliminary version
|
|
!-
|
|
subroutine load_a_field_from_file(field, fname)
|
|
real, dimension(:,:), intent(in) :: field
|
|
character(len=*), intent(in) :: fname
|
|
|
|
integer :: header(8)
|
|
integer :: io, foo
|
|
|
|
print *, "L) field size ", ubound(field, 1), "W", ubound(field, 2), "H"
|
|
|
|
!-
|
|
! how to check if the field array was valid ?
|
|
!-
|
|
|
|
open(newunit=io, file=fname, form='unformatted', status='old', &
|
|
action='read')
|
|
read(io) header
|
|
do foo=1, 8
|
|
print *, foo, header(foo)
|
|
enddo
|
|
|
|
STOP ' --- FUCKED UP BEYOND ALL REPAIR ---'
|
|
|
|
close(io)
|
|
|
|
end subroutine
|
|
!-----------------------------------------------------------------------
|
|
!-----------------------------------------------------------------------
|
|
|
|
end module
|