by Dan East » Dec 9, 2003 @ 5:35am
Since it is so expensive to transfer data to the display on MediaQ devices, it is better to first check to see if the backbuffer (what the game draws to) has been changed compared to what is currently being displayed (what has already been transferred to DRAM). If no change has taken place for a certain region of the buffer then that region does not need to be transferred to the display for that frame.
As Thierry said, the performance gain is dependant on how much of the screen is updated each frame. For example with a game like PacMan or Asteroids, only a small portion of the screen changes each frame, so very little information actually needs to be uploaded to the display hardware. However with a 3D engine, or a game in which the whole screen scrolls, the entire buffer will need to be sent if the camera is in motion.
Dan East
3D Pool tech demo - Performance/Compatibility testing wanted
