Transparent Window

I want to create an opengl Window without any background (fully transparent). I only want to see the 3D-Shapes, drawn over whatever application or desktop is visible behind.

With this I want to make a unique “Splah-Screen” for my application.

Is there a way to do this in pure OpenGL, without use of shaders?
I was thinking of something like clearing the screen with a transparent color, or maybe overlay windows.
But nothing I tried so far gave me the appropriate result. I would be glad if somebody could tell me if this is possible at all, and what keywords I should google for.

Of course, if somebody has a code example it would be great!

Regards, Juergen

AFAIK not actually opengl related, more of underlying desktop api thing. On win32 you could try this.


Thanks for your answer niko. I will try this today!

I tried that and got a bit disappointed: the performance of my extreme testapp (one-textured-quad rendered by fixedpipe) drops roughly tenfold. Another note of interest: opengl context which window has the colorkeying/alpha enabled degenerates to not-so-usefull “OpenGL 1.1.0/Microsoft Corporation/GDI Generic” -mode… sigh


A number of past projects managed to do that (with hardware accelerated GL), here my search results, from newest to oldest :…true#Post216469…true#Post194443…true#Post123974