RetroGaming Shorts Part 047 - Auto Chase
Auto Chase 1981 (CreatiVision)
I'm not sure how to explain what's special about this one. The CreatiVision uses the same TMS9918 video chip as ColecoVision, TI-994/a, MSX and others ... this chip did NOT support smooth scrolling.
And yet, Auto Chase has smooth scrolling. How? It's very clever graphics design. Even though the 8x8 pixel tiles can't budge, the graphics in Auto Chase are designed to be able to smooth scroll either horizontally or vertically while keeping a limit of only two different colors in each 8x8 tile.
One obvious idea is to simply surround each colored thing with an 8 pixel border between it and any other color.
A less obvious clever idea is to use colored 8x8 blocks. If you only scroll horizontally or vertically - but not both at the same time - then there will still only be 2 colors in each 8x8 tile.
A VERY clever idea is the way the cross shaped roofs work ... Examine closely to see how it works, keeping at most 2 colors in each 8x8 tile.
This could be useful for an AutoDuel or racing type game, especially one with two players, since it's possible to use side-by-side split screen. On the C64, you'd normally use hardware smooth scroll, but this doesn't really work for side-by-side.
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