Not long ago, I tried out a program from an OpenGL guidebook that was said to be double buffered; it displayed a spinning rectangle on the screen. Unfortunately, I don't have the book anymore, and I haven't found a clear, straightforward definition of what a buffer is in general. My guess is that it is a "place" to draw things, where using a lot could be like layering?
If that is the case, I am wondering if I can use multiple buffers to my advantage for a polygon clipping program. I have a nice little window that allows the user to draw polygons on the screen, plus a utility to drag and draw a selection box over the polygons. When the user has drawn the selection rectangle and lets go of the mouse, the polygons will be clipped based on the rectangle boundaries.
That is doable enough, but I also want the user to be able to start over: when the escape key is pressed, the clip box should disappear, and the original polygons should be restored. Since I am doing things pixel-by-pixel, it seems very difficult to figure out how to change the rectangle pixel colors back to either black like the background or the color of a particular polygon, depending on where they were drawn (unless I find a way to save the colors when each polygon pixel is drawn, but that seems overboard). I was wondering if it would help to give the rectangle its own buffer, in the hopes that it would act like a sort of transparent layer that could easily be cleared off (?) Is this the way buffers can be used, or do I need to find another solution?