I had a chance to play a couple of Tetris clones for the 2600 recently.
They all seem to pretty much just use playfield graphics for the blocks,
except Colin Hughes' Tetris26 which adds grid lines that look great but
seem to introduce some flicker in emulation (didn't try it on a real 2600,
and I'm only assuming it's the gridlines causing the flicker since it's
what's different.) Today while waiting in a Sam's Club checkout line it
occurred to me that there's no need for the flicker if you use both players
set to 3 copies each.
Suppose the playfield is set appropriately, and each player is set to
00010001
So you could set them to three copies each, both colored black, and get this:
1 1 2 2 3 3 4 4 5 5 6 6
where the 1's are player 1, copy 1, the 2's are player 2 copy 1, the 3's
are player 1 copy 2, etc. This is enough to get a 12 column wide tetris
game going. If that's not wide enough (I'm not a huge Tetris fan so I
don't know offhand) you could add both missiles and get 6 more columns for
a total of 18. As a bonus, you could set all the players' and missiles'
positions at the top of the screen, and just switch them off when you draw
the frame containing the game. You could add the horizontal grid lines by
vblanking every 8th scanline, or just changing the playfield color to black.
Am I missing something or would this accomplish what Colin has done without
introducing any flicker?
Rob
kudla@xxxxxxxxx ... http://kudla.org/raindog ... Rob
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