I have two surfaces. The source surface that I am blitting has a “surface alpha” set to give me semi transparency. The destination surface has a transparent colorkey. What I would like to have happen is that source surface makes semi transparent any pixels on the destination surface that are not transparent but otherwise ignores the colorkey pixels. Is this possible? Right now what happens is that the surface alpha of the source surface simply makes semi transparent everything on the destination surface. Including the the colorkey pixels (i.e. ones intended to stay transparent).
In brief is it possible to blit a surface alphaed surface such that it does not alter transparent color on the destination source? Maybe there is some blend I should use?
Thanks for any help.