[RobA]

I had asked a question in this post here about a script to randomly paint dabs based on a specified density map (see examples in that post).

I have cleaned it up, applied some error handling, as well as a bailout threshold (to stop it from going into an infinite loop). The starting point was this script by Charles Cave.

Here is the final script:

; random_density_map.scm
; by Rob Antonishen
; http://ffaat.pointclark.net

; Version 1.0 (20080408)

; Description
;
; Script to draw a specified number of random points with the currently 
; selected brush, using a density mask.
; Will appear in Filters->Map Menu
;

; based on random.scm
; by Charles Cave 
; http://members.optusnet.com.au/~charles57/GIMP

; License:
;
; 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.
;
; The GNU Public License is available at
; http://www.gnu.org/copyleft/gpl.html
(define (script-fu-random-density-map img inLayer inDensityMap inInvertMap inUseAlpha inIterations inMargin inBailout)

  (let* (
        (x1 0)
        (y1 0)
        (ctr 0)
        (x2 (car (gimp-drawable-width inLayer)))
        (y2 (car (gimp-drawable-height inLayer)))
        (xMap (car (gimp-drawable-width inDensityMap)))
        (yMap (car (gimp-drawable-height inDensityMap)))
        (x 0)
        (y 0)
        (map-type 0)
        (get-val 0)
        (test 0)
        (thresh 0)
        (*randompoint* (cons-array 2 'double))
        (drw-width 0)
        (drw-height 0)
		(lc 0)
        )

  ; define drawable area for the algorithm
  (set! x1 (+ x1 inMargin))
  (set! x2 (- x2 inMargin))
  (set! y1 (+ y1 inMargin))
  (set! y2 (- y2 inMargin))  (set! drw-width  (- x2 x1))
  (set! drw-height (- y2 y1))

  ;get map type:  RGB-IMAGE (0), RGBA-IMAGE (1), GRAY-IMAGE (2), GRAYA-IMAGE (3), INDEXED-IMAGE (4), INDEXEDA-IMAGE (5) 
  (set! map-type (car (gimp-drawable-type inDensityMap)))

  ; make sure maps isn't indexed
  (if (or (= map-type INDEXED-IMAGE) (= map-type INDEXEDA-IMAGE))
    (gimp-message "Density Map can not be indexed!") ; error
	(if (or (not (= x2 xMap)) (not (= y2 yMap)))
      (gimp-message "Density Map must be the same size as the active layer!") ; error
	    ;it begins here
		(begin 
		 (gimp-context-push)
		 (gimp-image-undo-group-start img)
		 
		 ; set up progress bar
		 (gimp-progress-set-text _"Rendering Random masked Image")
		 
		 (while (and (< ctr inIterations) (< lc inBailout))
		 
		   ; get a random location
		   (set! x (+ x1 (random drw-width )))
		   (set! y (+ y1 (random drw-height)))

		   ; get the pixel value at that spot
		   (set! get-val (cadr (gimp-drawable-get-pixel inDensityMap x y)))
		   
		   ; pick a number, any number
		   (set! thresh (random 255))

		   (if (and (= inUseAlpha TRUE) (= (car (gimp-drawable-has-alpha inDensityMap)) TRUE))   ; if using alpha
			 (begin
			   (set! test (aref get-val 3))   ; test threshold against alpha ( index 3)
			   (gimp-context-set-foreground (list (aref get-val 0) (aref get-val 1) (aref get-val 2)))  ;set brush colour
			 )
			 (if (or (= map-type GRAY-IMAGE) (= map-type GRAYA-IMAGE))  ;  else if greyscale
			   (set! test (aref get-val 0))  ; test threshold against colour ( index 0)
			   (if (or (= map-type RGB-IMAGE) (= map-type RGBA-IMAGE))  ; else if colour 
				 (set! test (/ (+ (aref get-val 0) (aref get-val 1) (aref get-val 2)) 3)) ; test threshold against average of r g and b
				 (set! test 255) ;  else threshold to full value (always draw)
			   )
			 )
		   )			   
		   (if (= inInvertMap TRUE)  ; reverse the map if invert option
			 (set! test (- 255 test))
		   )
		   (if (< thresh test)    ; compare threshold against random value
			 (begin
			   (set! ctr (+ ctr 1))       ; increment counter
			   (set! lc 0)
			   (aset *randompoint* 0 x)   ; set the paint array
			   (aset *randompoint* 1 y)
			   (gimp-paintbrush-default inLayer 2 *randompoint*) ; paint point
			   (gimp-progress-update (/ ctr inIterations))  ;update progress bar
			 )
		   )
		   (set! lc (+ lc 1))
		 )
		 
		 (if (>= lc inBailout)
		   (gimp-message "Bailout Parameter Exceeded - Aborted!") ; error      
		 )
		 
		 (gimp-progress-end)
		 (gimp-image-undo-group-end img)
		 (gimp-displays-flush)
		 (gimp-context-pop)
		)
    )
    )
  )  
)

(script-fu-register "script-fu-random-density-map"
                    "/Filters/Map/Random Density Map..."
                    "Draw a specified number of random points with the currently selected brush, using a density mask."
                    "Rob Antonishen"
                    "Rob Antonishen"
                    "April 2008"
                    "RGB*, GRAY*"
                    SF-IMAGE       "Image"         0
                    SF-DRAWABLE    "Drawable"      0
                    SF-DRAWABLE    "Density Map"   -1
				    SF-TOGGLE      "Invert Map"    FALSE
					SF-TOGGLE      "Use map alpha channel for Density and draw with map colour"  FALSE
                    SF-ADJUSTMENT  "Number of points to draw"     '(10 1 10000 10 100 0 0) 
                    SF-ADJUSTMENT  "Border Margin (pixels)"       '(0 0 100 1 6 0 0)
                    SF-ADJUSTMENT  "Bailout Threshold"            '(200 100 2000 10 100 0 0)
                    )

It uses the currently selected tool.

The density map can either be a greyscale map, in which case it will draw with the current pen and colour, or a layer with transparency. In that case, it will use the alpha for density and paint using the colour of the layer with transparency. See the examples in the other thread.

-Rob A>

[Oregonian]

I tried your script. Used the default settings. It said it failed ... something about bailout exceeded. It would be helpful if you'd post some instructions with it.

[RobA]

OK-

Create a new image (I'll use 300x300), black canvas. First we'll make a density map. Draw a white circle in the middle and blur it:


This is the density map. The script randomly picks coordinates in the image. Any black areas have no probability of getting a paint blob drawn. white will have a 100% chance, and grey in between.

Create a new white layer to actually apply the filter on. Pick a red circle 7 paintbrush and select the white layer then run the filter.


Here is the result. 200 paint dabs, following the density map.


Here is another sample density map:


and the resultant density filter result. This was a star brush in white on a black background, with 600 paint dabs:


Hope that clarifies the basic usage.

-Rob A>

[Oregonian]

Whoa! Something must have happened and I didn't get back to this. A very belated thank you for those instructions, RobA.

Here's a quicky little image I did using the script.

[lylejk]

No support of scaleable brushes unforuntately (ie., set the scale for a brush to 50%, but the script runs the brush size at full size). Anyway, can you add a scale option to this script Rob? I did just save one of my brushes to a smaller size, but it would be cool to no have to do so (have a lot of large brushes that I scale as I need too). :)

[Oregonian]

lylejk said:

No support of scaleable brushes unforuntately (ie., set the scale for a brush to 50%, but the script runs the brush size at full size). Anyway, can you add a scale option to this script Rob?

I second that request. :mrgreen:

[RobA]

lylejk said:

No support of scaleable brushes unforuntately (ie., set the scale for a brush to 50%, but the script runs the brush size at full size). Anyway, can you add a scale option to this script Rob? I did just save one of my brushes to a smaller size, but it would be cool to no have to do so (have a lot of large brushes that I scale as I need too). :)

Love to but it can't be done in Scheme as far as I can figure out.

-Rob A>

[lylejk]

That's cool Rob. Only affects gih brushes of course (can copy and past for gbrs). Had some fun with this cool Script-fu at GIMPChat by the way. :)

[Oregonian]

Here's a path to our playing. :mrgreen:

http://www.gimpchat.....php?f=11&t=530

[lylejk]

Here's one that i just did using my Arcimbolder GIH. Definitely a cool Script-fu. :)



Uploaded with ImageShack.us

[lylejk]

Just as a side note, I wonder if you are going to officially release this one on the Registry? I saw your link to your grid version. I happen to like both so I did (for my own personal use) edit the grid version so that it can co-exist with the full random version on my PC. I really do think it's worthy Rob of it. Really have enjoyed playing with your Script-fus over the past few years Rob. I actually created the Arcimbodo brush using your Rotating Brush assistant Script-fu. :)

[Rod_Blake]

I keep getting an integer error. =\