first real run, make a gif89a, need more tweaking

GravityField/essai.f90

@@ -1,54 +1,97 @@
+!-----------------------------------------------------------------------
 !
 !       project "gravity field"
 !
+!-----------------------------------------------------------------------
 program essai
   use realfield
+  use spitpgm               ! XXX
+
   implicit none
 
   type(massbody)          :: planet
   integer                 :: foo
-  planet%posx = 1337.314
-  planet%posy = 1664.666
-  planet%mass = 1e4
+  character (len=100)     :: filename
 
-  do foo=1, 10
-    call build_a_field(800, 600, planet)
-    planet%posy = planet%posy + 51.45
+  planet%posx   = 337.314
+  planet%posy   = 164.666
+  planet%mass   = 1e8
+  planet%serial = 42
+
+  do foo=0, 48
+    write (filename, "(a, i5.5, a)") 'WS/', foo, '.pgm'
+    call build_and_write_a_field(800, 600, planet, filename)
+    planet%posx = planet%posx + 6.99
+    planet%posy = planet%posy + 2.55
   enddo
 
   STOP 'YOLO'
 
-contains        !------------------------------------------
-!
-subroutine build_a_field(szx, szy, moon)
+contains
+!-----------------------------------------------------------------------
+!-
+!   compute a field with only one body; and write pic file
+!-
+subroutine build_and_write_a_field(szx, szy, moon, fname)
   integer, intent(in)                :: szx, szy
   type(massbody), intent(in)         :: moon
+  character (len=*), intent(in)      :: fname
 
-  integer                            :: ix, iy
-  real                               :: fx, fy
-  real                               :: grav, maxi, mini
+  real                               :: maxi, mini
   integer                            :: errcode
-  real, dimension(:,:), allocatable  :: field
+  real,    dimension(:,:), allocatable  :: field
+  integer, dimension(:,:), allocatable  :: greymap
 
   allocate(field(szx, szy), stat=errcode)
-   
-  do ix=1, szx
-    fx = real(ix)
-    do iy=1, szy
-      fy = real(iy)
-      grav = compute_gravity(ix, iy, moon) / 2180800.0
-      field(ix,iy) = grav
-    enddo
-  enddo
 
+  call compute_a_field(field, moon)
   maxi = maxval(field)
   mini = minval(field)
   print *, "field: ", mini, maxi, maxi-mini
 
+  allocate(greymap(szx, szy), stat=errcode)
+  greymap = 65535
+  ! 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
 
-                !------------------------------------------
+!-----------------------------------------------------------------------
+!-
+!   Compute the gravity field in a pre-allocated array relative
+!   to the massbody 'moon'. Nobody know where the magic number
+!   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
+!-----------------------------------------------------------------------
+!-----------------------------------------------------------------------
 
 end program