Hi The layer modes have now been ported to GEGL. As layer mode compositing with GEGL uses a different model than legacy layer mode compositing it deserves some elaboration. If you want to try out the new layer mode compositing you can do View -> Use GEGL in GIMP trunk. The new model is based on the one in the SVG 1.2 draft: http://www.w3.org/TR/2004/WD-SVG12-20041027/rendering.html The model used is Dca' = f(Sc, Dc) * Sa * Da + Sca * (1 - Da) + Dca * (1 - Sa) Da' = Sa * Da + Sa * (1 - Da) + Da * (1 - Sa) where Sc is the layer color (channels) Dc is the composite of the layers below Dc' is the result composite Xa means alpha channel Xca means pre-multiplied data f(Sc, Dc) is a blending formula Things to note about this model: The contribution to the end pixel that comes from the layer mode specific blending is proportial to Sa * Da, i.e. the subpixel area that contains both the layer and below composite in the Porter-Duff alpha compositing model. The rest of the contribution to the end pixel comes from the unblended (since there is nothing sensible to blend with) layer and below composite pixels: Sca * (1 - Da) + Dca * (1 - Sa). All layers independent of layer mode are treated as having an opacity and thus affect the alpha of the final composite. This new model creates a more consistent and predictable layer mode blending experience. Examples of differences compared to legacy layer mode compositing: 1. With a 50% opaque Addition mode layer put on top a 50% opaque Normal mode layer, the resulting composite has an opacity of 0.5 + 0.5 - 0.5 * 0.5 = 75% with GEGL layer mode compositing, but 50% with legacy layer mode compositing. 2. With a 100% opaque Addition mode layer put on top a completely transparent layer, the resulting composite becomes 100% opaque containing the unblended Addition mode layer pixels when using GEGL, but completely transparent when using legacy compositing. The current plan is to have add kind of compatibility rendering mode so that old .xcfs will render the same as in old versions of GIMP also when using GEGL. BR, Martin _______________________________________________ Gimp-developer mailing list Gimp-developer@xxxxxxxxxxxxxxxxxxxxxx https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
