Game Development Reference
In-Depth Information
Figure 2.1
Basic CRT drawing.
When the electron gun has finished drawing one frame, its aim will be positioned
at the bottom-right corner of the CRT. The amount of time it takes for the electron
gun to shift its aim from the bottom-right corner all the way back to the top-left
corner isknownasthe
vertical blank interval
(VBLANK). This interval isafrac-
tion of a second, though the precise timing depends on whether or not the CRT is
for a television or computer, and additionally the region where the device is inten-
ded for use.
Early gaming hardware such as the Atari did not have enough memory to store the
pixel data for the entire screen at once, which further complicated the rendering
systems on that system. This topic is covered in greater detail in David Crane's
GDC talk that was referenced in
Chapter 1
,
“
Game Programming Overview
.”
