I have a number of RGBA images that i am drawing one on top of another. When I draw an image behind an already drawn image that has an alpha channel, the alpha channel is ignored and what is behind is not blended with the image in front of it. Is there something in glAlphaFunc, glDepthFunc, or glBlendFunc that will make it test to see if there is an alpha channel in front of what will be drawn?
The Red Book will help you with that. Blending section.
You need to enable blending (glEnable) and then select a blending function (glBlendFunc). When rendering, draw all the opaques surfaces first, then disable the z buffer and draw the transparent ones back to front. The order in which you draw transparent polygons is important.
Good luck,
Dan.