; Script by Micha Pfeiffer
; Used to quickly generate a set of layers from a base layer which are all displaced by a random cloud layer.


(define (generate-lightning-layers inImg inLayer inNumberOfLayers inRoughness inIntensity inBeamsPerLayer)
	(let* (
		(width (car (gimp-drawable-width inLayer)))
		(height (car (gimp-drawable-height inLayer)))
		(newImg (car (gimp-image-new width height RGB)))
		(noise-layer (car (gimp-layer-new newImg width height RGB-IMAGE "Noise" 100 NORMAL-MODE)))
		(roughnessLow (/ inRoughness 2))
		(roughnessHigh (/ inRoughness 2))
		(i 0)
		(j 0)
		(layer-copy1 0)
		(selection 0)
		(film-image 0)
		(imgList (cons-array 1 'long))
		
		(offset-y 0)
		
		)

		(aset imgList 0 newImg)
		
		(srand (realtime))
		(set! roughnessHigh (- 255 roughnessHigh))
		
		(gimp-image-add-layer newImg noise-layer 0)
		
		(gimp-edit-copy inLayer)
		
		(while (< i inNumberOfLayers)
			; copy the selected layer, create a new displacement map, 
			;(set! layer-copy (car (gimp-layer-copy inLayer FALSE)))
			(set! j 0)
			(while (< j inBeamsPerLayer)
				(set! layer-copy1 (car (gimp-layer-new newImg width height RGBA-IMAGE "Displaced" 100 NORMAL-MODE)))
				(gimp-image-add-layer newImg layer-copy1 -1)
				;(gimp-layer-add-alpha layer-copy)
				(set! selection (car (gimp-edit-paste layer-copy1 FALSE)))
				(gimp-floating-sel-anchor selection)
				(plug-in-solid-noise RUN-NONINTERACTIVE newImg noise-layer 0 0 (rand 99999) (+ 1 (rand 2)) (* (/ 15 inBeamsPerLayer) (- inBeamsPerLayer j)) (+ 2 (rand 3)))
				(gimp-levels noise-layer HISTOGRAM-VALUE roughnessLow roughnessHigh 1.0 0 255)
				(plug-in-displace RUN-NONINTERACTIVE newImg layer-copy1 inIntensity inIntensity TRUE TRUE noise-layer noise-layer 0)
				
				(gimp-layer-set-opacity layer-copy1 (+ 70 (+ (rand 10) (* (/ j inBeamsPerLayer) 20))))
				
				(if (> j 0)
					(gimp-image-merge-down newImg layer-copy1 2)
				)
					
				(set! j (+ j 1))
			)
			
			(set! i (+ i 1))
		 )
		
		(gimp-image-remove-layer newImg noise-layer)
		
		(set! film-image (car (plug-in-film RUN-NONINTERACTIVE newImg 0 0 '(0 0 0) 0 "" '(0 0 0) FALSE FALSE 1 imgList)))
		
		; create a group to undo all the changes in this script with only one click
		(gimp-image-undo-group-start film-image)
		
		(set! offset-y (/ (- (car (gimp-image-height film-image)) height) 2))
		(gimp-image-crop film-image (car (gimp-image-width film-image)) height 0 offset-y)
		
		(plug-in-colortoalpha RUN-NONINTERACTIVE film-image (car (gimp-image-get-active-drawable film-image)) '(0 0 0))
		
		(gimp-image-delete newImg)
		
		; display everything you've done:
		(gimp-display-new film-image)
		(gimp-displays-flush)
			
		; end the undo group
		(gimp-image-undo-group-end film-image)
	)
)

(script-fu-register "generate-lightning-layers"
  _"Lightning..."
  _"Generate multiple displaced layers"
  "Micha"
  "Hrvoje Horvat"
  "01 April, 2011"
  "RGB* RGBA*"
  SF-IMAGE "Input image"    0
  SF-DRAWABLE    "Input drawable" 0
  SF-ADJUSTMENT _"Number of layers" '(5 1 200 1 10 0 1)
  SF-ADJUSTMENT _"Roughness" '(140 0 255 1 10 0 1)
  SF-ADJUSTMENT _"Intensity" '(6 0 50 1 10 0 1)
  SF-ADJUSTMENT _"Beams per Layer" '(3 1 10 1 5 0 1)
)

(script-fu-menu-register "generate-lightning-layers"
                         "<Image>/Filters/Custom")