I'm writing application, which should take screenshots of extrenal app/game (opengl).
So, as far as i have found it's done by using GL.ReadPixels (glReadPixels) method, but using it alone produces nullreference exception.
Could you enlight me how can i do it? Should i hook into game/ or catch app's graphicscontext/ bind frame buffer, if so, how it's done.
I coudn't find in docs about this stuff, only about creating your one context, which i don't need.
Some code example would be really great.
P.S. I'm new to OpenGL & OpenTK