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Strepto
Registered: Dec 2015
Posts: 11 |
Kefrens bars
I've been thinking about kefrens bars on the c64.
How do you think it is implemented?
Perhaps using repeated char lines and update the chars using cycle exact timing? |
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Oswald
Registered: Apr 2002
Posts: 5094 |
linecrunch crunches lines (char rows) down to a single rasterline, and this is used to move the screen upwards, so there should be badlines and not the same single rasterline displayed but in each rasterline a new char row in 1 pixel high glory ? |
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Krill
Registered: Apr 2002
Posts: 2980 |
Quoting Oswaldlinecrunch crunches lines (char rows) down to a single rasterline, and this is used to move the screen upwards, so there should be badlines and not the same single rasterline displayed but in each rasterline a new char row in 1 pixel high glory ? If you linecrunch continuously, with a write to $d011 each rasterline, there will be no badlines. Once you stop writing to $d011, the last rasterline of the current char row will be repeated, but after that, there will be normal badline DMA action and new lines as normal, with whatever line counter is left after all the linecrunching. |
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JackAsser
Registered: Jun 2002
Posts: 2014 |
Quote: linecrunch crunches lines (char rows) down to a single rasterline, and this is used to move the screen upwards, so there should be badlines and not the same single rasterline displayed but in each rasterline a new char row in 1 pixel high glory ?
A DMA fetch != VC->VCBASE
With line crunch you avoid bad line condition by setting $d011&7 != $d017&7, then at cycle 59 you trigger bad line condition to avoid entering IDLE, then repeat. So basically you trick the VIC-chip into badline condition, but at the same time avoid the actual DMA. |
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Oswald
Registered: Apr 2002
Posts: 5094 |
okay, some old c= hacking described it as really crunching down rows, and as I only ever used it for stretching (without knowing its the linecrunch effect) and not for moving screen, I didnt realize its really stretching. thanks :) |
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Golara
Account closed
Registered: Jan 2018
Posts: 212 |
Quote: okay, some old c= hacking described it as really crunching down rows, and as I only ever used it for stretching (without knowing its the linecrunch effect) and not for moving screen, I didnt realize its really stretching. thanks :)
Yeah, C64 names are weird, some refer to the visible effect (you can do 'FLD' in software I guess, just copy graphics down) others to the actual technique. Also using word "line" as in charline, "pixel" as actual one raster line... I always found "Different Y char position" so weird. It sounds awkward, but it's exactly what it is.
It's even better when you hear some scener and not just read it, cuz I pronouce all kids of stuff differently, for example FLI as just FLEE and not EF EL AY or DYSP as.. well, DYSP not DEE UAJ ES PEE |
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Krill
Registered: Apr 2002
Posts: 2980 |
Quoting Golarafor example FLI as just FLEE and not EF EL AY or DYSP as.. well, DYSP not DEE UAJ ES PEE As long as you don't pronounce "char" like "car"... =) |
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Smasher
Registered: Feb 2003
Posts: 520 |
Quote:It's even better when you hear some scener and not just read it, cuz I pronouce all kids of stuff differently, for example FLI as just FLEE and not EF EL AY or DYSP as.. well, DYSP not DEE UAJ ES PEE
hehe lol. not only routine acronyms, my head automagically translates all your handles/groups in a very Italian way. so I'm in "effequattrocigi" while "milleunocriu'" were first in opening the sideborder. and poor "federation against copyright" sounded like "f**k" :)
I remember the good old days chatting with sceners over PSTN... if you called you needed minimum 10 minutes to make me understand who you were. ehm, sorry for that :) |
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Street Tuff
Registered: Feb 2002
Posts: 88 |
https://bitbucket.org/streetuff/4krawall-final/src/master/kefre.. |
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CyberBrain
Administrator
Posts: 392 |
I included the source code in the zip-file for Kefrens Without For, if you want to have some example code to look at.
("igenigen code" means "againagain code" which means "speedcode" :)) |
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Oswald
Registered: Apr 2002
Posts: 5094 |
Quote: https://bitbucket.org/streetuff/4krawall-final/src/master/kefre..
that pha in the kernel is very sexy. |
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