Subject: Re: [stella] Polar to Cartesian Co-Ordinate Converter From: "Roger Williams" <mer02@xxxxxxxxxxxxx> Date: Sun, 21 Oct 2001 17:41:01 -0700 |
> Can you do your demos with single scanline accurate movement? > These demos were thrown together to provide a platform for demonstrating the pol2cart routine. My eventual plans involve using pol2cart in the kernal, which means that Y cannot be preserved. The single scanline vertical resolution is also so much finer than the horizontal that it seemed pointless to go for it when something "almost as good" could be realized much more easily. That said, there is no reason one couldn't use Y as the counter for a more normal kernal where VDEL would work, giving 1-scanline resolution. I didn't do that because you have to write both GRPx all the way down the screen. (If you turn on VDEL for a player in this kernal, it doesn't appear at all if it's not positioned within the other player 's and it bleeds down to the bottom of the screen if its bottom is below that of the other player.) With an appropriate kernal all three demos should work nicely at 192 vertical, and the polar routine can even correct the aspect ratio. But my main focus was on the polar routine and with rotation, and to my eye it looks better to have nearly-square pixels, and they're more compatible with 2's complement 8-bit math anyway. The kernal I wrote for this sucks on many levels, but it did the job of demonstrating my polar coordinate routine. I expect anyone who studies the sprite movement demos to quickly figure out how to clean them up for more general-purpose work. The hard stuff is there, and the lazy stuff is obvious. --Roger Williams - Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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