[EMAIL PROTECTED] (2003-03-22 at 1850.44 +0100): > I've just completed a Script-Fu script that some people may find quite > useful (I've missed this functionality myself several times). The > purpose is to convert a layer's Alpha channel into a mask for editing > it and later using Apply Layer Mask to put it back. The idea is > similar to what QuickMask does with selections.
Maybe you can poke at the attached script, a bit old, for reference see http://groups.yahoo.com/group/gimpi/message/1479 and other posts about tribes 2 video game. This one does not lose the selection, IIRC. GSR
;;; The GIMP -- an image manipulation program ;;; Copyright (C) 1995 Spencer Kimball and Peter Mattis ;;; ;;; script-fu-alpha-to-mask ;;; Moves the transparency of a layer to the layer mask ;;; Copyright (c) 2001 Guillermo S. Romero ;;; famrom infernal-iceberg.com ;;; ;;; ### 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. ;;; ;;; You can get a copy of the GNU General Public License from ;;; http://www.gnu.org/, the site of the Free Software Foundation, Inc. ;;; ;;; ### Versions ### ;;; ;;; 1.00.00 Initial release (bug in L,C&P thumbnails?) ;;; 1.01.00 Support for existent mask added (merges transp and mask) ;;; ;;; ### Inline Documentation ### ;;; ;;; # Intro # ;;; Tribes 2, a 3D game, uses RGBA PNGs as skins. The RGB are used for ;;; the colour, and the A for the quantity of environment mapping. ;;; Or at least that is what I have read. ;;; ;;; # Requirements # ;;; This plugin was developed with Gimp 1.2.1 CVS ;;; Check all your plugins and scripts in the DB Browser before reporting bugs ;;; It merges the current layer mask, if any, so you keep all info ;;; ;;; # Parameters # ;;; None the user can play with ;;; ;;; # Debugging and to-do # ;;; Look for ";; @" comments ;; Helper functions from neon-logo.scm (define (set-pt a index x y) (prog1 (aset a (* index 2) x) (aset a (+ (* index 2) 1) y))) (define (AlphaSpline) (let* ((a (cons-array 6 'byte))) (set-pt a 0 0 255) (set-pt a 1 127 255) (set-pt a 2 255 255) a)) ;; The function (define (script-fu-alpha-to-mask inImg inDrw) ;; Start (gimp-undo-push-group-start inImg) ;; Merge mask if any (set! OrigMask (car (gimp-layer-mask inDrw))) (if (not (= OrigMask -1)) (gimp-image-remove-layer-mask inImg inDrw APPLY)) ;; Create a new mask (set! Mask (car (gimp-layer-create-mask inDrw ALPHA-MASK))) (gimp-image-add-layer-mask inImg inDrw Mask) ;; Unerase (gimp-curves-spline inDrw 4 6 (AlphaSpline)) ;; End (gimp-undo-push-group-end inImg) ;; @ The image thumbnail does not update nice ;; @ Undo then redo and it refreshes to the right state ;; @ Or change to another image and back, to force the refresh too ;; @ A refresh call is missing in the C code, maybe fixed for Gimp 1.4 (gimp-displays-flush)) ;; Register! (script-fu-register "script-fu-alpha-to-mask" _"<Image>/Script-Fu/Utils/Alpha to layer mask" "Moves the transparency of a layer to the layer mask" "Guillermo S. Romero" "2001 Guillermo S. Romero" "2001-04-29" "RGBA GRAYA" SF-IMAGE "Image where to work" 0 SF-DRAWABLE "Drawable to modify" 0)
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