I work on commercial project using (of course unfortunately) DirectX (there is only "that" on the XBOX), but I am a huge
fan of OpenGL (as you may have guessed) and my home engine is written with this API. I just can't find in the OpenGL API
a function very usefull which exists in DirectX : the blending operation. I'm not talking about the blending sources (I mean glBlendfunc)
, it seems like in openGL the blending equation is fixed (result = fragment * sfactor + framebuffer * dfactor) and not in D3D (very weird?). With
this renderstate D3DBLENDOP we can substract or add (usefull to do substractive blending). Is there a similar function/renderstate in OpenGL?