Fortraneries/Fraktalism/mkmandel.f90

!-----------------------------------------------------
!		MANDELBROT SET
!-
!    refactored Thu 29 Dec 2022 03:21:16 PM CET
!-
!-----------------------------------------------------
!-
subroutine plotsomething(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

    print *, "> plotsomething"

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

    !   initialise constants
    ! 
    maxiter =  1984

    !   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*8,  255)
            else
                rval = (mod2 + abs(real(start)*aimag(start))) * 666.666
                pic(ix, iy)%g = mod(int(rval), 180) 
                ! 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

!-----------------------------------------------------
! 
!    this is the main programm
! 
program mkmandel
    use pixrgb

    implicit none

    interface
      subroutine plotsomething (pic, start)
          use pixrgb
          type(t_pixrgb),   intent(inout), dimension (:,:) ::  pic
          complex,   intent(in)                            ::  start
      end subroutine plotsomething
    end interface

    type(t_pixrgb), allocatable     ::    pic(:,:)
    integer                         ::    angle
    real                            ::    radangle, radius
    real                            ::    stx, sty
    character (len=80)              ::    filename

    write(0, *) "-------- making some mandelbrot -------"

    allocate(pic(1152, 900))

    do angle = 0, 1500

        call rgbpix_set_to_zero(pic)

        radangle = float(angle) * 0.01664
        radius   = float(angle) / 1500.0
        write (filename, "(a, i5.5, a)") "frames/mandel/", angle, ".pnm"
        ! filename = trim(filename)
        print *, "#### passe ", angle, radangle, trim(filename)

        stx = radius * (sin(radangle*3.9) + sin(radangle*5.36))
        sty = radius * cos(radangle*3.3)

        call plotsomething (pic, complex(stx, sty))
        call rgbpix_spit_as_pnm_8 (pic, trim(filename))
        print *
    enddo

    print *, "     [DONE]"

end

!-----------------------------------------------------