Fortraneries/Fraktalism/mandelbrots.f90

!-----------------------------------------------------
!		MANDELBROT SET
!-
!    refactored Thu 29 Dec 2022 03:21:16 PM CET
!    refactored Sat 31 Dec 2022 12:37:03 PM CET
!-
!-----------------------------------------------------
!-
module mandelbrots
    implicit none
contains
!-----------------------------------------------------------------------

subroutine mandelbrot_one(pic, start)
    ! use cmplxmath
    ! use imagetools
    use pixrgb

    implicit none

    type(t_pixrgb), intent(inout), dimension (:,:)  ::  pic
    complex, intent(in)                             ::  start
    ! type (CenterMag), intent(in)             :: cz

    integer   :: ix, iy, width, height
    real      :: fx, fy, mod2, rval
    complex   :: za, zb, cste
    integer   :: iter, maxiter
    logical   :: escape

    ! write(0,*) "> plotsomething"

    width  = ubound(pic, 1)
    height = ubound(pic, 2)
    ! print *, "  pic size ", width, height
    print *, real(start), aimag(start)

    !   initialise constants
    ! 
    maxiter =  3456

    !   enter megaloop
    ! 
    do iy = 1, height
        fy = (float(iy) / float(height/3)) - 1.5
        !! print *, "line  ", iy, fy
        do ix = 1, width
            fx = (float(ix) / float(width/3)) - 2.0
            !-------------------------------------
            !     working on the current pixel
            za   = start
            cste = complex ( fx, fy )
            iter = 0
            escape = .FALSE.
            do while (iter .lt. maxiter)
                zb = (za * za) + cste
                mod2 =  real(zb)*real(zb) + aimag(zb)*aimag(zb)
                !! print *, "mod2  ", mod2
                if (mod2 .GT. 4.0) then
                    escape = .TRUE.
                    exit
                endif
                za = zb
                iter = iter + 1
                !! print *, "ZA ITER ESCAPE", za, iter, escape
            enddo
            if (escape) then
                pic(ix, iy)%r = mod(iter*12, 255)
                pic(ix, iy)%b = mod(iter*7,  255)
            else
                rval = (sqrt(mod2) + abs(real(start)*aimag(start))) * 9e2
                pic(ix, iy)%g = mod(int(rval), 210) 
                ! pic(ix, iy)%g = mod(iter, 255)
                ! pic(ix, iy)%b = mod(iter*11, 255)
            endif
            !-------------------------------------
        end do           ! fin boucle sur X
    end do

end subroutine
!-----------------------------------------------------
end module
!-----------------------------------------------------