Linux framebuffer graphics and VSync

Question

I\'m making a game in C that works on the linux framebuffer. So far I have a red 100x100 square that moves in tandem with the mouse, just like a pointer. I have implemented

Answer 1

This isn't the correct way to do double-buffering. You're right to do all the painting on a back-buffer, but then you do a memcpy to transfer the data to the front. A screen refresh could easily happen during the copy.

To do this properly, you should only have to switch a pointer to the data; not copy the data itself. With the Linux framebuffer device, this is done by having a "virtual" screen that is twice as large as the physical screen, and using an offset variable to set whether you're showing the top or bottom half. You can query the size and set offset using the FBIOGET_VSCREENINFO, FBIOPUT_VSCREENINFO, and FBIOPAN_DISPLAY ioctl calls.

This page briefly gives some details about this: http://www.ummon.eu/Linux/API/Devices/framebuffer.html

All the relevant data structures are in the linux/fb.h header file.