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Starry sky

A script-fu for The Gimp

Example

Bild das mit dem Skript-fu 'Starry sky' erzeugt wurde

Description

"Starry sky" is a script-fu for the Gimp. It generates a nighty sky image with plenty of stars. You choose the number of stars. The stars are placed at random positions. You'll never get twice the same image. The luminosity and contrast of the background are configurable too.

The script has been tested with The Gimp version 2.2.9 on Linux SuSE and with The Gimp version 2.2.10 on Windoze.
The script version 1.10 has been tested with The Gimp version 2.4.0 on Linux Ubuntu 7.10 Gutsy Gibbon.

Versions

2007.10.24 : The current version is 1.10 and has been adapted to The Gimp 2.4.

Download:

Click into the blue frame below where the script is listed.
Type Control-A to select the complete text of the script.
Type Control-C to copy the script to the clipboard.
Go to your text editor (gedit, Kate, Aedix, Notepad, etc) and type Control-V to paste the script.
Save it as a file named starry-sky.scm

Linux Ubuntu or other Gnome:   use the text editor gedit or bluefish

Linux Kubuntu or other KDE:   use the text editor Kate or Quanta

Mac OS X:   use the text editor Smultron

Windoze:   use the text editor Aedix (free), or Notepad (but beware of the file extension .txt which is unwanted, the script file must have the extension .scm and not .scm.txt)

Other text editors are ok too, but word processors are not. Do not use Word, OpenOffice or similar tools.

Installation:

Copy starry-sky.scm into one of the directories registered in the Gimp preferences under Folders/Scripts.

Linux Ubuntu and many others:
  /home/[username]/.gimp-2.n/scripts   or   /usr/share/gimp/2.0/scripts

Linux SuSE:
  /home/[username]/.gimp-2.n/scripts   or   /opt/gnome/share/gimp/2.0/scripts

Windoze:
  C:\.gimp-2.n\scripts   or   C:\program-files\gimp2.n\share\gimp\scripts

Then go to the menu Xtns (in The Gimp) and select Xtns / Script-Fu / Refresh Scripts. That's it.
The script can be called in the menu Xtns / Script-Fu / Patterns / Starry Sky...

Script-fu starry-sky.scm for The Gimp (english version)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
; SCRIPT-FU-STARRY-SKY produces an image of a nighty sky with stars at random
; version 1.01  2006.07.11
; version 1.10  2007.10.24, migration to Gimp 2.4
; Copyright (c) 2006-2007 Tharsice Demand <www.td-e.com>
;
;This program is free software; you can redistribute it and/or
;modify it under the terms of the GNU General Public License
;as published by the Free Software Foundation; either version 2
;of the License, or (at your option) any later version.
;
;This program is distributed in the hope that it will be useful,
;but WITHOUT ANY WARRANTY; without even the implied warranty of
;MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;GNU General Public License for more details.
;
;You should have received a copy of the GNU General Public License
;along with this program; if not, write to the Free Software
;Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
;
;Copy of the license at http://td-e.com/site/gpl.php

(define (script-fu-starry-sky width height smalls mediums bigs bglum bgcon)

(let* (
      ; Save the foreground & background colors
      (old-fg (car (gimp-palette-get-foreground)))
      (old-bg (car (gimp-palette-get-background)))

(image (car (gimp-image-new width height RGB)))
      (layer-one (car (gimp-layer-new image width height RGB-IMAGE "Bottom" 100 NORMAL-MODE)))
      (layer-two)
      (ii 0)
      (ns 0)
      (xs 0)
      (ys 0)
      (nm 0)
      (xm 0)
      (ym 0)
      (nb 0)
      (xb 0)
      (yb 0)
      (lum 0)
      (pixw (cons-array 3 'byte))
    )

(srand (realtime))
    (aset pixw 0 255)
    (aset pixw 1 255)
    (aset pixw 2 255)

(gimp-image-undo-disable image)
    (gimp-image-add-layer image layer-one 0)

; Set the fg to white, bg to black
    (gimp-palette-set-foreground '(255 255 255))
    (gimp-context-set-background '(0 0 0))
    (gimp-drawable-fill layer-one 1)  ;0 FG, 1 BG, 2 white

; generating small stars
    (while (< ns smalls)
      (set! ns (+ ns 1))
      (set! xs (rand width))
      (set! ys (rand height))
      (set! lum (+ (rand 160) 32))
      (aset pixw 0 (+ lum (rand 64)))
      (aset pixw 1 (+ lum (rand 64)))
      (aset pixw 2 (+ lum (rand 64)))
      (gimp-drawable-set-pixel layer-one xs ys 3 pixw)

; preparing the exit of the loop
      (set! ii (+ ii 1))
      (if (> ii 10000) (set! ns smalls))
    ) ; end of loop

; generating medium stars
    (set! ii 0)
    (while (< nm mediums)
      (set! nm (+ nm 1))
      (set! xm (rand (- width 1)))
      (set! ym (rand (- height 1)))
      (set! lum (+ (rand 96) 128))
      (aset pixw 0 (+ lum (rand 32)))
      (aset pixw 1 (+ lum (rand 32)))
      (aset pixw 2 (+ lum (rand 32)))
      (gimp-drawable-set-pixel layer-one xm ym 3 pixw)
      (gimp-drawable-set-pixel layer-one (+ xm 1) ym 3 pixw)
      (gimp-drawable-set-pixel layer-one xm (+ ym 1) 3 pixw)
      (gimp-drawable-set-pixel layer-one (+ xm 1) (+ ym 1) 3 pixw)

; preparing the exit of the loop
      (set! ii (+ ii 1))
      (if (> ii 10000) (set! nm mediums))
    ) ; end of loop

; generating big stars
    (set! ii 0)
    (while (< nb bigs)
      (set! nb (+ nb 1))
      (set! xb (rand (- width 2)))
      (set! yb (rand (- height 2)))
      (set! lum (+ (rand 64) 160))
      (aset pixw 0 (+ lum (rand 32)))
      (aset pixw 1 (+ lum (rand 32)))
      (aset pixw 2 (+ lum (rand 32)))
      (gimp-drawable-set-pixel layer-one xb yb 3 pixw)
      (gimp-drawable-set-pixel layer-one (+ xb 1) yb 3 pixw)
      (gimp-drawable-set-pixel layer-one (+ xb 2) yb 3 pixw)
      (gimp-drawable-set-pixel layer-one xb (+ yb 1) 3 pixw)
      (gimp-drawable-set-pixel layer-one (+ xb 1) (+ yb 1) 3 pixw)
      (gimp-drawable-set-pixel layer-one (+ xb 2) (+ yb 1) 3 pixw)
      (gimp-drawable-set-pixel layer-one xb (+ yb 2) 3 pixw)
      (gimp-drawable-set-pixel layer-one (+ xb 1) (+ yb 2) 3 pixw)
      (gimp-drawable-set-pixel layer-one (+ xb 2) (+ yb 2) 3 pixw)

; preparing the exit of the loop
      (set! ii (+ ii 1))
      (if (> ii 10000) (set! nb bigs))
    ) ; end of loop

(define layer-two (car (gimp-layer-copy layer-one 1)))
    (gimp-image-add-layer image layer-two -1)
    (gimp-image-set-active-layer image layer-two)
    (plug-in-gauss-rle 1 image layer-two 3 1 1)
    (plug-in-normalize 1 image layer-two)
    (gimp-layer-set-mode layer-two SCREEN-MODE)

(define layer-three (car (gimp-layer-copy layer-one 1)))
    (gimp-image-add-layer image layer-three -1)
    (gimp-image-set-active-layer image layer-three)
    (plug-in-gauss-rle 1 image layer-three 6 1 1)
    (plug-in-normalize 1 image layer-three)
    (gimp-layer-set-mode layer-three SCREEN-MODE)

(define layer-four (car (gimp-layer-copy layer-one 1)))
    (gimp-image-add-layer image layer-four -1)
    (gimp-image-set-active-layer image layer-four)
    (plug-in-gauss-rle 1 image layer-four 32 1 1)
    (gimp-levels layer-four 0 0 (- 44 bgcon) 1 0 255)
    (plug-in-gauss-rle 1 image layer-four 16 1 1)
    (gimp-colorize layer-four 236 64 bglum)
    (gimp-layer-set-mode layer-four SCREEN-MODE)

(gimp-layer-set-name layer-one "Stars")
    (gimp-layer-set-name layer-two "Stars contour")
    (gimp-layer-set-name layer-three "Stars halo")
    (gimp-layer-set-name layer-four "Sky bg")

; Restore the old foreground & background colors
    (gimp-palette-set-foreground old-fg)
    (gimp-palette-set-background old-bg)

(gimp-display-new image)
    (gimp-image-undo-enable image)
  )
)

(script-fu-register "script-fu-starry-sky"
                    "<Toolbox>/Xtns/Script-Fu/Patterns/Starry Sky..."
                    "Creates a starry sky pattern."
                    "T. Demand <td-e.com>"
                    "T. Demand"
                    "2007.10.24"
                    ""
                    SF-ADJUSTMENT "Image width"  '(256 16 8192 16 64 0 1)
                    SF-ADJUSTMENT "Image height" '(256 16 8192 16 64 0 1)
                    SF-ADJUSTMENT "Small stars"  '(200 20 10000 10 10 0 1)
                    SF-ADJUSTMENT "Medium stars" '(20 2 1000 1 10 0 1)
                    SF-ADJUSTMENT "Big stars"    '(4 1 100 1 2 0 1)
                    SF-ADJUSTMENT "Background luminosity" '(32 0 64 1 10 0 0)
                    SF-ADJUSTMENT "Background contrast" '(24 0 40 1 1 0 0)
)

Sponsorship

If you find the script 'Starry sky' useful and want to support the developer, you can

License

The GNU general public license applies to the script-fu starry-sky.scm above.

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