+grafixbmp Posted May 10, 2009 Share Posted May 10, 2009 Was just contemplating h position and was wondering if a missle has its h position set, and is active for several scanlines, would any change to size width alter the h position a few pixels on the same frame depending on the current size set for each scanline? I had heard this once but didn't know how a change to size would be percieved for every scanline following changes made. like for scanlines 20 to 21 set at 4 x and for scanlines 22 to 24 at 2 x. If the alignment on the left side were diffrent that would mean that an HMOVE would need to be triggered to compensate, correct? Quote Link to comment Share on other sites More sharing options...
SeaGtGruff Posted May 10, 2009 Share Posted May 10, 2009 Changing a missile's width without changing its horizontal position will affect where it ends on a scanline, but will *not* affect where it begins: On the other hand, changing a *player's* width without changing its horizontal position *can* cause it to shift to the right by one color clock: Specifically, it will start at the same color clock position as long as it is a single-wide player-- no matter how many copies of it are displayed-- but it will start one color clock later if it is a double- or quadruple-wide player. Michael Quote Link to comment Share on other sites More sharing options...
Wickeycolumbus Posted May 10, 2009 Share Posted May 10, 2009 On the other hand, changing a *player's* width without changing its horizontal position *can* cause it to shift to the right by one color clock Specifically, it will start at the same color clock position as long as it is a single-wide player-- no matter how many copies of it are displayed-- but it will start one color clock later if it is a double- or quadruple-wide player. Michael I never knew about that. Is it a hardware bug? Quote Link to comment Share on other sites More sharing options...
SeaGtGruff Posted May 10, 2009 Share Posted May 10, 2009 On the other hand, changing a *player's* width without changing its horizontal position *can* cause it to shift to the right by one color clock Specifically, it will start at the same color clock position as long as it is a single-wide player-- no matter how many copies of it are displayed-- but it will start one color clock later if it is a double- or quadruple-wide player. Michael I never knew about that. Is it a hardware bug? I don't think it's a bug, but I can't give you an explanation of why it happens. The TIA hardware notes that were written by Andrew Towers talk about horizontal positioning, but I don't understand all the technical aspects of it. However, there are several people on this board who can probably explain this behavior, so hopefully one of them will chime in! Michael Quote Link to comment Share on other sites More sharing options...
+grafixbmp Posted May 11, 2009 Author Share Posted May 11, 2009 doesn't the ball have any size settings and if so, do they stay aligned properly? Quote Link to comment Share on other sites More sharing options...
Omegamatrix Posted May 11, 2009 Share Posted May 11, 2009 doesn't the ball have any size settings and if so, do they stay aligned properly? Yep, the ball has size settings. They are actually a part of the CTRLPF register, bits D5 and D4. I wrote a small program and it seems like the ball always begins at the same place, despite its width. I tried it on real hardware with the Krok and it looks okay. I get some weird scrolling in both Stella and Z26 though. I think it might be my ancient video card. TestBall.zip Quote Link to comment Share on other sites More sharing options...
+stephena Posted May 11, 2009 Share Posted May 11, 2009 doesn't the ball have any size settings and if so, do they stay aligned properly? Yep, the ball has size settings. They are actually a part of the CTRLPF register, bits D5 and D4. I wrote a small program and it seems like the ball always begins at the same place, despite its width. I tried it on real hardware with the Krok and it looks okay. I get some weird scrolling in both Stella and Z26 though. I think it might be my ancient video card. TestBall.zip Yes, you're probably using software mode in Stella (and in z26, this is the only mode available). The artifacts you're seeing are because the screen updates aren't synchronized to your monitor refresh rate, and for most (all?) operating systems, it's impossible to do so in software mode. If you switch to OpenGL mode and turn on OpenGL vsync, the updates will be much smoother. Quote Link to comment Share on other sites More sharing options...
Omegamatrix Posted May 11, 2009 Share Posted May 11, 2009 Yes, you're probably using software mode in Stella (and in z26, this is the only mode available). The artifacts you're seeing are because the screen updates aren't synchronized to your monitor refresh rate, and for most (all?) operating systems, it's impossible to do so in software mode. If you switch to OpenGL mode and turn on OpenGL vsync, the updates will be much smoother. Yep, that worked for the refresh rate. Thanks. I also changed the demo slightly, and commented the source a little more. No big deal, but it's more readible. TestBall.zip Quote Link to comment Share on other sites More sharing options...
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