nesdev.com
http://forums.nesdev.com/

How did f-1 Race work?
http://forums.nesdev.com/viewtopic.php?f=2&t=15847
Page 2 of 2

Author:  zeroone [ Fri Apr 28, 2017 2:05 pm ]
Post subject:  Re: How did f-1 Race work?

thefox wrote:
allocates the tiles dynamically (i.e., only the tiles that have non-empty CHR data will have non-zero nametable entries), and uses palette switching to get double buffering.


I don't understand. :/

Author:  tepples [ Fri Apr 28, 2017 2:27 pm ]
Post subject:  Re: How did f-1 Race work?

Palette switching means that in even frames, bitplane 0 (consisting of bytes $00-$07 of each tile) gets displayed while bitplane 1 (consisting of bytes $08-$0F of each tile) gets filled, and vice versa in odd frames. To display only bitplane 0, set the palette to black, white, black, white, so that bitplane 1 is ignored. To display only bitplane 1, set the palette to black, black, white, white, so that bitplane 0 is ignored.

Dynamic allocation means it stores a partial nametable in main RAM, filled with solid black tiles. When trying to draw pixels into a tile whose current tile number is the solid black tile, it allocates a new tile number for that tile. When trying to draw pixels into a tile that is not the solid black tile, it uses the same tile number that was already there.

Page 2 of 2 All times are UTC - 7 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/