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peskanov
Account closed
Registered: Mar 2004
Posts: 17 |
Sprites over blanked screen
Hi there; I am working on a small effect using sprites. I don't need any kind of backdrop, just the sprites and raster interrupt in the odd lines.
To free cycles I am poking the $d011 register in each IRQ to disable bad lines.
Well, the question is that I have been looking some demos to see the ways used by others coders, and to my surprise I have disassembled a demo which displays the sprites over a blanked screen!?
It's Comajob from Crest. The sprite strech effect works with the 4th bit of $d011 cleared, along all the screen (as far as I have seen).
I am totally puzzled, is there a way to display sprites over a deactivated screen?
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peskanov
Account closed
Registered: Mar 2004
Posts: 17 |
Yes, that's the trick I was looking for. I didn't have the slightest idea about this trick.
Thanks a lot for the fast reply! |
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Radiant
Registered: Sep 2004
Posts: 639 |
NP, I was in your situation before JackAsser pointed me to that thread. :-) As was apparently he before that thread existed... |
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Cybernator
Registered: Jun 2002
Posts: 154 |
<rantmode>
A while before Oswald's thread was posted, I thought of this trick (not knowing if it was used/known before as it wasn't mentioned in VIC-article or anywhere else), and said to myself: "WOW! I'm having a worldfirst. Wait till the dudez hear about it." :PPP
</rantmode>
And btw, I named it hypra-screen. (and I still have no idea why :P) So I have to ask, does this trick have a formal name? |
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TDJ
Registered: Dec 2001
Posts: 1879 |
Quote: <rantmode>
A while before Oswald's thread was posted, I thought of this trick (not knowing if it was used/known before as it wasn't mentioned in VIC-article or anywhere else), and said to myself: "WOW! I'm having a worldfirst. Wait till the dudez hear about it." :PPP
</rantmode>
And btw, I named it hypra-screen. (and I still have no idea why :P) So I have to ask, does this trick have a formal name?
Yes, it's called hyper-screen. |
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Oswald
Registered: Apr 2002
Posts: 5094 |
while we're at it... invalid modes can be made visible by turning sprites behind them, maybe one of them is easyer to adress as the normal bitmap. So set up a sprite layer behind the invalid gfx bits, and experiment, here we have something YET to explore :) |
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Ninja
Registered: Jan 2002
Posts: 411 |
BTW, have you read the VIC-Article yet, Oswald? ;) |
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Cybernator
Registered: Jun 2002
Posts: 154 |
TDJ: Isn't hyper-screen a screen with (partially) removed borders? IIRC, that's what VIC article says. |
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JackAsser
Registered: Jun 2002
Posts: 2014 |
(out of topic but as an answer to Oswald's post)
Actually Pinball Dreams uses the illegal Bitmap+ECM mode for the dot-matrix display for two reasons:
1) The ECM properties saves us memory due to wrapping.
2) The pixels are automatically black no matter what's in the screen which is good since that's the linecruncher area and we only want a black grid.
Any other demos/games that makes use of these modes? |
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Cruzer
Registered: Dec 2001
Posts: 1048 |
invalid/illegal modes - is that the $3fff thing? |
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Frantic
Registered: Mar 2003
Posts: 1648 |
Quite unrelated: Illegal opcodes.. Illegal graphics modes.. What other illegal activities are there? :) I guess one could say that SounDemoN uses an "illegal" SID-trick when he locks the noise oscillator in his Pico!-tune to create new waveforms. ;) Illegal CIA-settings? No? :) |
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