Subject: Re: [stella] parallel efforts / Invaders From: Erik Mooney <emooney@xxxxxxxxxxxxxxxx> Date: Fri, 16 Mar 2001 02:28:11 -0500 |
On Thu, 15 Mar 2001 14:29:51 +0100, you wrote: >There also is enough time to apply the shifted graphics. Remember >what you are seeing is the second player copy, so the RESPx happens >quite a few pixels away from the actual display position. That's the part I missed; you're right. >And now I remember what the problem was that I was thinking of. >If you only have one invader in a row, it will display both >of it's player copies, since from the second line on, the only >hit to RESPx happens always at the same time in the line. You >will have to special-case that, like position that player normaly >during the setup phase for that row and then don't hit RESPx >during the display. I ran into that problem too. Funny how making the code do the complex case of 11 invaders makes it unable to do the simple case of 1 invader. >> I thought I actually had the pixel shifting solved, or at least reasonably >> minimized. Also, it's only a one pixel shift, and it happens because >> there are nine pixels between successive RESPx hits, but only 8 pixels >> between NUSIZ copies. Argh, I'm getting curious enough to set up the 2600 >> again and try this out, seeing as how the various emulators aren't perfect >> with regards to the repeating-sprites... > >Well, you might want to have a closer look at the display of >your program then. Or maybe not. ;-) The invaders in the third >row for example are all shifted to the left. And on my system >and on the emulators it's two pixels. Look at my demo. The lower >invaders are 7 pixels wide and there is the one pixel gap between >two invaders, yet the second to last invader in the row is >attatched to the invader before him. See, I have no idea what my own program is doing anymore. :) Yes, I see that now, although I don't understand why it's two pixels instead of one, or even why there's any offset at all. Every single invader in my demo is drawn as a second copy of the player (NUSIZx is always 1.) Why I didnt see it before was that I had programmed the thing with either a full invader formation, or the same invaders missing in each row. I only put in the some-missing invader formation as a quick hack to show off the routine right before posting it. >Oh BTW, I know exactly how you feel. I had to dig out my old code >yesterday too and try out the sprite shifting. I almost got it >working, but I seriously need to clean up the code before I can >post something here. I guess that's what I get for always making >fun of Andrew's commenting habbit. ;-) > >So Erik, tell me why is it that I always feel challenged to >write some VCS code after reading your posts. ;-) Because I've become the guru of this list, dispensing advice from on high while not dirtying my own hands in such mortal matters anymore. :) - Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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