Marcus von Appen wrote:
Should we change this to take alpha into account for the BLEND_* args as well and only apply the default alpha blending, if no BLEND_* args are passed?
Maybe what's needed is another set of flags to specify what transfer function to use for the alpha channel, independently of the RGB channels. A good place to look for ideas on this would be the set of blending functions specified by OpenGL. It seems to be fairly comprehensive and is based on a lot of experience of what people have found useful. In particular, it has modes which specify the alpha combining function separately, which seems to be what is needed here. -- Greg