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Rudi
Account closed
Registered: May 2010
Posts: 125 |
DYPP
Hi,
DYPP - Different Y Pixel Position.
I don't seem to find an explanation on this effect on C64 on codebase or anywhere. Maybe its in another thread here on csdb, then please provide an link.
I know the basics of sines, ive made sinescroll on PC, but its easier there since you can look up the framebuffer directly, via sine-tables and so on.
Im wondering how this effect is easily made on C64. I believe there are more than one way, but i guess one way is slower than the other; for example moving each column-bit (inside a char) in realtime. The other way I think is having the chars animated, similar to a twister. Though, im thinking each angle is used for lookup table. I just dont seem to get it right in my mind to start coding on this effect. I've seen several early cracktros and demos that does this very fast, but haven't had the time to reverse-engineer the binaries. If you have any tips and info i'd appreciate it, or even better; write an explanation for codebase.
Thanks |
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chatGPZ
Registered: Dec 2001
Posts: 11092 |
i think you want to look for DYCP or DYSP on codebase :) |
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TWW
Registered: Jul 2009
Posts: 541 |
The DYPPs I made in the past was done something like this:
Fetch charset data AND bit pattern and store with sine-index offset (1x1 charset).
lda Character
asl
asl
asl
tax
lda CharsetData,x
ldx sinus
and #%1111000
sta CharsetDisplayBuffer,x
and so on for the remainder. Off course the AND will determine how many routines you have to write.
There are some optimisations for bigger characters which was used where you only update the to and bottom of the character, not every pixel in between and resulted in looong codestreams ;-) |
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Rudi
Account closed
Registered: May 2010
Posts: 125 |
groepaz: are you sure this is the same as DYPP? of course i could start with those, but i want to start with the difficult.
TWW: interesting ill try out this.
By the way, I started an irc-channel (ircnet) #c64coders. pls join, i want it to be purely coding related. and spread the word. no lamers pls! |
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Digger
Registered: Mar 2005
Posts: 421 |
A neat example of a char based DYPP can be found in Obornik (coded by Brush). |
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Rudi
Account closed
Registered: May 2010
Posts: 125 |
Digger: nice. yes, the sine-scroll in that demo is a good example of what i want to learn how is done. |
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Rudi
Account closed
Registered: May 2010
Posts: 125 |
Ok, I forgot to turn of invite on the channel. I wanted to keep the lamers out. If you are irc user, Pls (auto)join #c64coders (ircnet) if you want hang on a pure coders channel. Thx |
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ChristopherJam
Registered: Aug 2004
Posts: 1370 |
Does anyone know which production holds the area record for freeform DYPP? (ie, not relying heavily on solid 8x8s in the source) |
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Axis/Oxyron
Registered: Apr 2007
Posts: 91 |
There exists an old, but pretty good DYPP based on VSP in Anal Intruder. And AFAIK the best completely dynamic DYPP is in Mekanix. |
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chatGPZ
Registered: Dec 2001
Posts: 11092 |
Quote:are you sure this is the same as DYPP?
i have no idea what "DYPP" should be exactly, and how its different from DYSP, to be honest :=) |
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HCL
Registered: Feb 2003
Posts: 716 |
I'm afraid we're going off-topic here, but to me a DYSP means Different Y SideborderSprite Position, which is quite far from a DYPP. |
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