On Wed, May 20, 2009 at 9:07 PM, Daniel Johannsen <dj@xxxxxxxxxxxxxxxxxx> wrote: > Hi, > yes, your assumption is right. I start the painting process with layers > only for shapes and silhouettes. > Then i add a "layer group" with the mask property (or in photoshop-terms > a group of "clipping mask"-layers) > to each of the shape-layers. The layers inside the layer group mask define > volume, texture, athmospheric perspective, etc. of the shape they are > connected to. > > So to say, the layer group mask has the property of a transparency > value. This value is defined > by the alpha-value of the layer the group is assigned to. > > Here is a link that shows the photoshop approach quite well: > http://photoshopcontest.com/tutorials/23/clipping-mask-101.html > > You are absolutely right, every layer in the layer group should maintain > their independent transparency, > but in addition inherit the transparency of their layer group mask. GEGLs XML format implements such per composition subtree masks. It even allows building these masks using other filters, allowing for instance to create a mask for a layer group using a blurred text layer. I've found the underlying technical approach used to represent the GEGL compositing graph as a tree in those systems to provide all the power that should be needed. Finding sufficiently rich mappings to a user interface most probably using some higher level abstract compositing operations remains a challenge for GIMP in exposing such functionality. An example composition following the underlying model of OpenRaster using low-level operations: crop over translate apply_opacity gaussian blur render text hue-saturation subtract some more noise multiply some more noise some noise pattern checkerboard Some of the low-level ops like the combination of translation and a compositing operation like over (and perhaps even the application of opacity) can be folded into a single UI level concept to avoid having too many individual items in the compositing tree. What the aboive example renders is three noise layers that are combined with different layer modes, a blurred piece of text is used as the overall group opacity for the noise and the noise itself is composited over a checkerboard background. Finally the whole image is cropped (this crop op would probably in fact be the canvas dimensions). See http://create.freedesktop.org/wiki/OpenRaster , http://pippin.gimp.org/oxide/ and http://gegl.org/ for more information. -- «The future is already here. It's just not very evenly distributed» -- William Gibson http://pippin.gimp.org/ http://ffii.org/ _______________________________________________ Gimp-developer mailing list Gimp-developer@xxxxxxxxxxxxxxxxxxxxxx https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
