Refreshing Window

I’m pretty new to VC++, MFC & also OpenGL. I’m working on a ray tracing project using VC++, with MFC & OpenGL. I realised that OpenGL will refresh the WHOLE window when there is any changes done on the graphics. May I know if there is anyway to refresh only the changed area??
Please guide. Thanks.


glScissor(…) restricts drawing to a certain portion of the screen.
theres an extension or 2 for windows u might be interested in as well GL_WIN_SWAP_HINT and a KTX extension

Thanks for your reply, but I can’t find any details about glScissor() in the OpenGL Super Bible. I tried search in this website, found only little information.
As I realised, it’s the Invalidate() which force to redraw the whole window. I have a Inside/Outside testing function within a ray tracing function. Should I call this glScissor() before I call this ray trace function?

I’ve found some information on glScissor() in MSDN of VC++. It is drawing a restricted rectangle area. What I wish to do is to test the points within a rectangle that bounds my polygon. IF the points are inside the polygon, redraw it; IF outside of the polygon but inside the rectangle, ignore it without redrawing. May I know that in this case, is it possible to use glScissor()?