Greetings all, Say you had a skybox, and you wanted to simulate going from day to night. Using multipass rendering and blending you could alpha them in and out. If your implementation supports multitexturing is it possible to set some sort of alpha when applying the two textures to do the same thing? Thanks

Simple answer, you don''t need it for what your doing. Blending is more than adequate. And is well more than fast enough.
heck, if you were worried about speed you could simple dump the interpolated image to a texture at run time, since it would only change noticably every minute or so.

otherwise,

if you want to interpolate between texture units then look into GL_ARB_texture_env_combine. Interpolation is a bit buggy on nvidia cards though.