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Radiant
Registered: Sep 2004
Posts: 639 |
Release id #3310 : Mentallic
There has been some discussion in the release comments about how the "9 sprite trick" in the last part is achieved. Some have said that one of the letters (the 'I') is made using the $3fff (or whatever bank) byte. But wouldn't that be impossible to achieve, due to the requirement of exact timing?
I really haven't played around much with that byte, but I figure it would need to be changed at exactly the right cycle, and then immediately changed back the next - which, unless I'm mistaken, is impossible without utilizing a REU or something. |
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Ninja
Registered: Jan 2002
Posts: 404 |
iopop is correct. The "i" is done using $D016. For example, if you change the screen-x-offset from leftmost to rightmost in the middle of the screen, you create a "hole" showing the background color. Really neat trick! |
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JackAsser
Registered: Jun 2002
Posts: 1989 |
It becomes even better when crossbow does characters with holes in them (see Krestage, Krestage). Now how's that possible? =D |
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Ben
Account closed
Registered: Feb 2003
Posts: 163 |
As far as Mentallic goes, set $d015 to 0 and $3fff to e.g. $55, for good fun.. |
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Spinball
Registered: Sep 2002
Posts: 87 |
wasn´t that $d016 trick invented by cruzer?
One Year Camelot 3 (last part) |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
The first demo with the "$D016 gap trick" which comes to my mind is indeed 1 Year Camelot III. The disadvantage of that trick is that you can only produce a gap of 1-7 pixels and not any byte pattern, so Crossbow/Crest later invented another trick in "Krestage" which can display ANY byte. |
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JackAsser
Registered: Jun 2002
Posts: 1989 |
@graham: For the all mighty CSDB record, how does that trick work? |
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HCL
Registered: Feb 2003
Posts: 716 |
Just read the answer in the code :).
;prepare..
LDA #$ff
STA $3FFF
LDA #COLOR
STA $D021
;put gfx..
LDX #PATTERN
LDA #0
STX $3FFF
STA $D021
Strange enough, $3fff seems to be updated 2 cycles slower than $d021.. So we get two bytes of gfx. Set $d016 to #$cf and 7 pixels will go away.. left is 9 pixels, where two of them are copies of the same 3fff-bit. That gives us 7 pixels to make a random pattern of. Done :). |
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CyberBrain
Administrator
Posts: 392 |
Much of this was already discussed at 9th Sprite so check that thread aswell |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
@HCL: Why "strange enough"? It's obvious because before the VIC can display the byte, it first has to be fetched from memory and be passed to the bitmap shifter. |
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Tch
Account closed
Registered: Sep 2004
Posts: 512 |
Thanx guys...I keep on learning. 8)
But probably I´ll never use this knowledge.
Nice trick though and I really like the demo.
Anyway,Panoramic Designs always had a special place in my heart.
Ahead of their time!! |
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HCL
Registered: Feb 2003
Posts: 716 |
@Graham: Oh, of course.. And $d021 uses the kitchen door to get into the screen faster, right ;). Hmm, it's obvious that i make some dudes here look kinda stupid, and it's equally clear that you make me look stupid :))). So be it. |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
Hehe :) |
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WVL
Registered: Mar 2002
Posts: 886 |
when it comes to looking stupid, who doesn't when he (or she) is being compared to crossbow? ;-)
btw, I don't think either of you guys look stupid, but I do think HCL shouldn't wear any baseball caps and Graham should try to avoid the Gul-Dukat look a bit more :-)
anyway, so actually the scroller in Krestage can have a mix width of 7 pixels then? (or 9 ofcourse, but that's not totally free)... hmmm.. well, doesnt really matter, most charsets only use 7 pixels anyway. |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
No, I tried it yesterday. You only get 6 pixels. |
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HCL
Registered: Feb 2003
Posts: 716 |
Hmm, that's really strange. Xbows scroller is also only 6 pixels wide, so probably that's it. |
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WVL
Registered: Mar 2002
Posts: 886 |
only 6 pixels? I have to try this too :-) |
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Scout
Registered: Dec 2002
Posts: 1568 |
This demo needs more exposure! |
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WVL
Registered: Mar 2002
Posts: 886 |
And also, i still didnt try it. |
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Clarence
Registered: Mar 2004
Posts: 119 |
Now that you brought this thread back to life, I remember
the inspiration to do the lower border 10 sprites dycp in Irrational, came from this discussion.
There you have two arbitrary seven pixels wide patterns, and for the first time in the history (of these kind of 3fff based tricks) the effect uses *non-black* background. :)
Ofcourse I'm not called Xbow, so nobody gives a shit when somebody else does something like that. :D
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