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Luke
Registered: Dec 2004
Posts: 19 |
Sprite Stretching or what? :>
So i found it on old disk:
Only screenshots here:
Sorry for Polish language in comments, but no time for explain all into English.
First screenshot - route sprite setting. 8 sprites, $54 y , x from 00 step $18++.
http://www.platine.fajnastacja.pl/IMG_0918.JPG
Second screenshot, old irq routine: set $ff in $d017, waiting some cycles and $00 -> $d017 + dec $3fff. And it's all.
http://www.platine.fajnastacja.pl/IMG_0917.JPG
Third screenshot : How is it works? $3fff used in sprite + extra multiplexer for free without any changes of $d001, and $00 in $d017 :) What is this?:D
http://www.platine.fajnastacja.pl/IMG_0919.JPG
Sry for crap screens, no time for it at all.
I'm wondering - multiplexer for free :)
Btw. If that change $d017 from $ff to $00 are in next line, then 2x multpilexer in Y :)
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pernod
Account closed
Registered: Nov 2004
Posts: 25 |
Hey, it looks like you have re-invented "sprite crunching"! It is a kind of weird, but very useless trick. |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
useless? not really =) |
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Oswald
Registered: Apr 2002
Posts: 5094 |
well I havent seen a use of it other than xbow being able to display more sprites.. |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
well yes, its a nice trick everytime you want a spritelayer over some kind of fli routine. not terribly useful for most other stuff, ok =) |
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Oswald
Registered: Apr 2002
Posts: 5094 |
ah forgot about that =) |
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Luke
Registered: Dec 2004
Posts: 19 |
Is here any "sprite crunching" manual?:D |
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WVL
Registered: Mar 2002
Posts: 902 |
Quote: Is here any "sprite crunching" manual?:D
Xbow once wrote a complete list of what's happening in one of his demos. I guess it's this one :
Krestage press runstop in the multiplexer part to get the list ;) |
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Luke
Registered: Dec 2004
Posts: 19 |
thank you :) |
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ready.
Registered: Feb 2003
Posts: 441 |
just adding one question to this thread instead of opening a new one. I am trying to do a $d017 sprite stretch, but with bad lines active. I can repeat the same sprite line only until a bad line occurs. It seems to me that in order to repeat a sprite line n-times, $d017 must be set only at a certain x position within a raster line (corresponding to an x coord near the left part of the visible screen area). So setting $d017 when no bad line occurs is feasible, but when a bad line comes, the portion of the screen where $d017 must be changed is taken by the VIC and cannot be accessed by the CPU.
So, is this feasible or shall I remove bad lines? Of course I want badline in order to keep other gfx too. |
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Oswald
Registered: Apr 2002
Posts: 5094 |
I'm no expert, only thing I know you can steal back some cycles with inc / dec, try that. |
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