copper l!nes (zx spectrum)

[xxl]

zx spectrum:

http://www.pouet.net/prod.php?which=49698

 

 

and a8:

http://atari.pl/copper.obx

[Tezz]

Fast!

[+MrFish]

zx spectrum:

http://www.pouet.net/prod.php?which=49698

 

 

and a8:

http://atari.pl/copper.obx

 

Any way to avoid the shearing/flickering?

[Heaven/TQA]

since 20 years I never captured how these "kefren bars" work... can someone tell me what is driving the illusion? because I don't believe that the screen is been rendered fully every frame...

[MaPa]

since 20 years I never captured how these "kefren bars" work... can someone tell me what is driving the illusion? because I don't believe that the screen is been rendered fully every frame...

 

Once I looked in monitor of some demo how the kefrens bar are done. IIRC "every" line of DLI was reffering to the same address (in this case to zero page for speed) and just after every WSYNC you add new data and in VBLANK you just clear the one line (will clear "whole" screen) and repeat. But this demo does it in different way (just looked at DLIST...).

Edited July 6, 2008 by MaPa

[Heaven/TQA]

Ahhh... Mapa, does make sense a little bit... so the 1 line is rendered on the fly every scanline, right? but you don't have much time each line to render a bit?

[MaPa]

Ahhh... Mapa, does make sense a little bit... so the 1 line is rendered on the fly every scanline, right? but you don't have much time each line to render a bit?

 

I never tried to do it, but if you have 1 kefren bar you just add/render like 1 byte per line, you just need to calculate new position on some sinus trace or can have it precalculated. Remember that whenever you put data onscreen they are repeated vertically to the bottom until you put some other data in that place, so you render "only" the top edge of the bar and the "wall" down from there is there automatically. It's simplified but the basics can be like that.

[Heaven/TQA]

yeah. now I got it... First i thought they shuffle around the lines (simple on Amiga and Atari800 due to LMS command of the "copper list") but it seems it is even far more simpler... have to try that on my own...

[eru]

MaPa is right, on Atari this should be done by re-using the same line.

Unfortunately, you can't do this on speccy, and I think XXL just did one-to-one conversion.

 

Here's a quick hack how it should work/look:

executable: http://homepages.cwi.nl/~marcin/a8/copperu.xex

sources: http://homepages.cwi.nl/~marcin/a8/copperu.asx

 

1 hour of work from scratch, not optimized at all.

 

btw, on Atari there is a 256-byte intro that does something similar: http://www.pouet.net/prod.php?which=9761 (the part not on the screenshot)

[Heaven/TQA]

damned... Eru again faster than me...

[Oswald]

MaPa is right, on Atari this should be done by re-using the same line.

Unfortunately, you can't do this on speccy, and I think XXL just did one-to-one conversion.

 

yep. I have once coded a c64 version. you need an lda screen,x and mask,x ora bargfx,x sta screen,x sequence for each byte updated. (x contains the horizontal offset of the bar, and use clever tables) how many times you do this depends on how wide bars do you want (and at wider ones you dont need to mask the middle). on a8 colors could be changed on a line basis to make it look niftier than c64 versions, and there is more time to do wider bars. (only wsync at the top of the screen, then keep a constant timing for each line to save speed.. imho)

Edited July 6, 2008 by Oswald

[Heaven/TQA]

Oswald, how did you do kefrens on c64? render a complete screen or gfx window?

[eru]

It's amazing... I looked at the effect, and I though: "Hmm, it's a bit different than kefren bars" - w r o n g

So I reimplemented the same thing

 

Btw, Oswald, I think you need to use Y in the AND/ORA combination

[Oswald]

Oswald, how did you do kefrens on c64? render a complete screen or gfx window?

 

there's a vic trick (costs 6 cycles / line at best) which will repeat a gfx line endlessly.

[Oswald]

It's amazing... I looked at the effect, and I though: "Hmm, it's a bit different than kefren bars" - w r o n g

So I reimplemented the same thing

 

Btw, Oswald, I think you need to use Y in the AND/ORA combination

 

yeah probably but I got a hangover and some insomnia as an excuse:)

[eru]

've been there done that

[carmel_andrews]

So....Copper lines and 'Copper Lists' are the same thing then (just a different way of programming)

[xxl]

no, copperlist is something like dli ( not exactly ).

[Bryan]

A Copper List is like a Display List, except it's much more flexible and can program registers other than just video ones, so it removes most of the need for things like DLI's by automating register changes as the screen is drawn.

 

The name Copper was chosen because it sounds like Co-processor.

 

-Bry

[Heaven/TQA]

So in theory I could reposition hardwaresprites on the fly by the copper list? shame on me that I have an a500 and a1200 and never touched programming them...

[Rybags]

From memory, you can get copper instructions to load just about any hardware register relating to graphics/sound.

 

But there's a limit per scanline. Got the hardware manual here, just too lazy to pull it out.

 

I also have owned Amigas for > 15 years, but never really got into programming them beyond batch type files.

 

I guess the awesome games just made us too busy in that regard - on the ST I got into a fair amount of programming.

[Heaven/TQA]

I was more into demos watching on A1200... not so often played games (same time I got my SNES).

[bfollett]

What file format is .obx? Can you use Atari800win to run it? I can't figure out how.

 

Thanks,

 

Bob

[+Philsan]

What file format is .obx? Can you use Atari800win to run it? I can't figure out how.

Rename the extension in .xex and the program will start with emulator.

[+Philsan]

Marcin, what is the colored bar in the lower part of the screen of your beautiful copperu?