On Thu, 13 Feb 2025, Andrea paz wrote: > Tomorrow I'm going to do some testing, including the change you > suggested: \u201cOK, but now you can take the arith_subtract function, > change the expression for alpha to something like A_OUT = A(s); or > even A_OUT = 1;, and you'll get green\u201d
Andrea, I have found, the standard Overlay effect seems not to make arithmetic with emulated transparencies if the project has no alpha channel. Therefore I made a small correction: now the fact of having alpha (== 1) or not having alpha (== 0) is also given to user functions as an additional parameter HAS_ALPHA. The patch to CGG source, cgg-blend-noalpha.diff.gz, is in attachment. 5 BlendAlgebra functions have to be changed due to this modification. For CGG distribution, they are in that patch. For the 'ovl2' example the updated functions are in the archive ovl2-upd.tar.gz, also in attachment. And yes, arith_subtract without alpha became green:) All the other functions are not affected by the modifications, either they do not use alpha at all, or the arithmetic on it constantly gives 1.0 anyway. _______________________________________________________________________________ Georgy Salnikov NMR Group Novosibirsk Institute of Organic Chemistry Lavrentjeva, 9, 630090 Novosibirsk, Russia Phone +7-383-3307864 Email [email protected] _______________________________________________________________________________
cgg-blend-noalpha.diff.gz
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ovl2-upd.tar.gz
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