; FP-Retro-Background script

; This is an updated version of the default GIMP line nova script.
; The purpose for modifying it was to create a simple retro-style background.
; I've add options for setting the foreground/background colors so that it will automatically
; create the retro background with the user's chosen colors.  The default settings work pretty
; well for most image sizes, but above 1024X768, things get a little unusual.  I don't quite
; understand the underlying math for most of the script, so at the moment, I can't change that.
; However, a future goal for this script is to allow the user to choose the center point for the rays
; and allow it to work well on any image size.

; I also modified the script to allow it to work better with the Undo option.  The original script
; added a line in the "let* block" to turn turn off any existing selection and save it to a channel.
; By doing this, it was impossible to Undo everything in one step.  I moved that command out from the 
; "let* block" and into the script itself.
;
; Updated 1/11/2008:
;
; Gives user the option to save the selection created by the script as a channel for use later on. Default for
; this option is to save the selection.  Thanks to ClayOgre (http://clayogre.deviantart.com/) for the suggestion.
; 
; Also, told the script to add its own layer to make the background from, rather than requiring the user to do so
; beforehand.  Thanks Photocomix (http://photocomix-resources.deviantart.com/) for the suggestion.

; Updated 5/19/2008: Added option to let user place the center point of the "sunburst" at any location.  Also added
; ability to use almost size of image to create selection.  Previous script was limited in that regard.
;
; Updated script on October 5, 2008 to ensure compliance with GIMP 2.6 standards.



(define (fp-retro-background img drw center CX  CY  num-of-lines corn-deg offset variation fg-color trans-bg bg-color save-select addSun sunRadius)
  (let* (
        (*points* (cons-array (* 3 2) 'double))
        (modulo fmod)                        ; in R4RS way
        (pi/2 (/ *pi* 2))
        (pi/4 (/ *pi* 4))
        (pi3/4 (* 3 pi/4))
        (pi5/4 (* 5 pi/4))
        (pi3/2 (* 3 pi/2))
        (pi7/4 (* 7 pi/4))
        (2pi (* 2 *pi*))
        (rad/deg (/ 2pi 360))
        (variation/2 (/ variation 2))
        (drw-width (car (gimp-drawable-width drw)))
        (drw-height (car (gimp-drawable-height drw)))
        (drw-offsets (gimp-drawable-offsets drw))
        (old-selection 0)
        (radius (* 20 (max drw-height drw-width)))
        (index 0)
        (dir-deg/line (/ 360 num-of-lines))
        (retro-layer 0)
        )

    (define (draw-vector beg-x beg-y direction)

      (define (set-point! index x y)
            (aset *points* (* 2 index) x)
            (aset *points* (+ (* 2 index) 1) y)
      )
      (define (deg->rad rad)
            (* (modulo rad 360) rad/deg)
      )
      (define (set-marginal-point beg-x beg-y direction)
        (let (
             (dir1 (deg->rad (+ direction corn-deg)))
             (dir2 (deg->rad (- direction corn-deg)))
             )

          (define (aux dir index)
                   (set-point! index
                               (+ beg-x (* (cos dir) radius))
                               (+ beg-y (* (sin dir) radius)))
          )

          (aux dir1 1)
          (aux dir2 2)
        )
      )

      (let (
           (dir0 (deg->rad direction))
           (off (+ offset (- (modulo (rand) variation) variation/2)))
           )

        (set-point! 0
                    (+ beg-x (* off (cos dir0)))
                    (+ beg-y (* off (sin dir0)))
        )
        (set-marginal-point beg-x beg-y direction)
        (gimp-free-select img 6 *points* CHANNEL-OP-ADD
                          TRUE                ; antialias
                          FALSE                ; feather
                          0                    ; feather radius
        )
      )
    )

    
; Allow for the GIMP settings to be restored prior to running the script

(gimp-context-push)


    (gimp-image-undo-group-start img)
    (set! old-selection (car (gimp-selection-save img)))
    (gimp-selection-none img)
    (srand (realtime))

    
; Create new layer for the Retro Background, add it to the image, and fill it with color

(set! retro-layer (car (gimp-layer-new img drw-width drw-height RGBA-IMAGE "Retro Background Layer" 100 NORMAL-MODE)))
(gimp-image-add-layer img retro-layer -1)
(gimp-drawable-fill retro-layer TRANSPARENT-FILL)
(gimp-context-set-foreground fg-color)
(gimp-context-set-background bg-color)

    (if (= trans-bg FALSE)
    (gimp-edit-fill retro-layer BACKGROUND-FILL)
    )
 
   (while (< index num-of-lines)
      (if (= center TRUE)
		(begin
		(set! CX (/ drw-width 2))
		(set! CY (/ drw-height 2))
		)
	)
	(draw-vector (+ (nth 0 drw-offsets) CX)
                   (+ (nth 1 drw-offsets) CY)
                   (* index dir-deg/line)
      )
      (set! index (+ index 1))
    )


(if (= addSun TRUE)
    (begin
    (gimp-ellipse-select img (- CX (* 0.5 sunRadius)) (- CY (* 0.5 sunRadius)) sunRadius sunRadius CHANNEL-OP-ADD TRUE FALSE 0)	
    )
)
    (gimp-edit-fill retro-layer FOREGROUND-FILL)

(if (= save-select TRUE)
    (gimp-selection-save img)
)
    
    (gimp-image-set-active-layer img retro-layer)
    (if old-selection
      (begin
        (gimp-selection-load old-selection)
        (gimp-image-remove-channel img old-selection)
      )
    )
    	
	(gimp-displays-flush)
	(gimp-image-undo-group-end img)

; Return GIMP settings back to those used prior to script

(gimp-context-pop)
    
  )
)

(script-fu-register "fp-retro-background"
  "<Image>/Filters/Render/FP Retro Background..."
  "Create a Retro Style Background with Chosen Colors"
  "Art Wade"
  "Art Wade"
  "October 5, 2008"
  "RGB*"
  SF-IMAGE       "Image"               0
  SF-DRAWABLE    "Drawable"            0
  SF-TOGGLE     "Place sunburst at center of image?" TRUE
  SF-ADJUSTMENT "Center X Coordinate"     '(10 0 9999 1 1 0 1)
  SF-ADJUSTMENT "Center Y Coordinate"   '(10 0 9999 1 1 0 1)
  SF-ADJUSTMENT "Number of lines"     '(10 10 1000 1 1 0 1)
  SF-ADJUSTMENT "Sharpness (degrees)" '(8 0.0 10.0 0.1 1 1 1)
  SF-ADJUSTMENT "Offset radius"       '(0 0 2000 1 1 0 1)
  SF-ADJUSTMENT "Randomness"          '(1 1 2000 1 1 0 1)
  SF-COLOR      "Foreground Color"    '(0 0 0)
  SF-TOGGLE     "Transparent Background?" FALSE
  SF-COLOR	    "Background Color"	  '(255 255 255)
  SF-TOGGLE     "Save selection created by script in a channel?" TRUE
  SF-TOGGLE     "Add Sun?" FALSE
    SF-ADJUSTMENT "Sun Radius"     '(10 10 9999 1 1 0 1)

)