Rendering contexts usually have a solid color on the background (black or whatever, see the image below):
I'm wondering if it's possible to setup a window, with no decorations AND with the transparent background, while allowing me to render OpenGL stuff on it.
This would give the illusion that the triangle is floating on the screen. The transparent background should allow you to see the desktop or other applications that might be behind it.
Could you please exemplify with source code?
Platform: Windows (win32 only)
Best Answer
After spending some reputation on a unsuccessful bounty to get some help on this issue, I finally realized how complex was the problem I was interested in.
The few individuals that have accomplished this task don't share much. During my research I found different ways to achieve what I was looking for. One of the most interesting ones is AeroGL, and it shows snippets of code using a technique that was not mentioned so far, which is rendering the graphics to a device-independent bitmap (DIB).
To close this thread permanently, the source code below implements that technique. The code itself is a slight modification of an application presented here (big thanks to Andrei Sapronov Y.).
The end result can be seen in the image below:
The code has been tested on Windows XP (32-bits) and Windows 8.1 (32-bits). Enjoy!