Transparency on multiple objects
 

I'm having a problem with transparency. I'm constructing an engine where I want the user to be able to fade its individual components to partially transparent or completely transparent, therefore being able to see the different components working.

When I modify the alpha values of the different geometries to anything but 1.0 or 0.0, there is an accumulation error in that it doesnt accumulate the color thru multiple transparent geometries. I found the 'drawOrder' function which helps a little, but since the different geometries arent in such a straight forward order (i.e. they wrap around each other), there are still problems. I get background color coming thru where there should be geometry color.

Is there any way to get a true alpha buffer and accumulate values rather than just assigning drawing order?

Thanks