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Joe Musashi

[DPC+] Zaxxon HD Demo

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Now and then when reading the forum, I come across a post that inspires me to try out some new things. This time it a was repost of Andrew Davie's Chronocolour ™ Mario demo. Despite the flicker it looks fantastic, so I was wondering if it would also be useful for dynamic content in a game.

 

As an example, I wanted to see how Zaxxon would look with this technique. This requires more memory and compute resources than a standard 2600 has, so the demo uses DPC+ and ARM code and therefore needs a Harmony or Melody card to run on a real machine.

 

I have to tell you how wonderful I think this is. I wonder if you could figure out how to only flicker two screens and get some of the benefits with more on the fly line color changes. I like the fact that you use the technique to achieve a wonderful color palette and scrolling effect on the 2600. (I've only tried in Stella at the moment.) How much memory in total does the harmony cart have? I also feel like (made an attempt at it but haven't gone back since learning better searching techniques) given a particular image the default Chronocolour palette may not be the best choice. I know it maximizes the available gamut in color space but not sure that is really the best alternative. Maybe black as a foreground color and gray as the background is better. The closer the lumen values of the two colors the less apparent the flicker is, and certainly a 30 Hz flicker would be less than the 15 Hz this gets. But with a Harmony Cart and the fancy DPC+ tricks that you do it seems to me you could make a nice video loop using this technique expanded to a custom matched palette. If you were able to integrate a game engine like this into the interleaved flicker then a movie using a custom palette per frame would be child's play. :) That would be an awesome demo.

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There is no color palette with Chronocolour™.

For all colors it must cycle three RGB colors every scan line.

Look at it zoomed up in Stella's Debugger. The actual color values are a light green, light orange, and blue.

No other colors are used.

You can vary the luma of the 3 chosen colors as was done in the Parrot.bin demo.

 

Picking just 2 of the 3 RGB values, you could get some interesting blending, and that would be 30 Hz flicker, but not full color or what appears to be white.

As in orange, green would = red, green, yellow, black colors for the bitmap.

Placing a playfield color or a background color would add more color effects...

 

P.S. I LOVE how the H / L are made with changing Ball sizes and with the background colors and playfield mask! So brilliantly clever.

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There is no color palette with Chronocolour™.

For all colors it must cycle three RGB colors every scan line.

Well, you can choose any three colors here, just like we did in Boulder Dash. So you can give different scenarios different color themes.

 

To achieve white, the third color has to be complementary to the combined colors one and two.

 

We have explained that in a bit more detail in the Boulder Dash manual, end of page 12.

Edited by Thomas Jentzsch
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Finally had time to try out the demo, Joe. SICK! Wish I had a harmony to try it on real hardware. Very slick implementation of the CC technique. We had often discussed what Zaxxon VCS could be but that blows it away, even if just a tech demo. :D

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On 10/8/2015 at 9:50 AM, iesposta said:
User ScumSoft was working on a DPC+ bitmap kernel in assembly but has not been very active here the last year or so. His Eggventure's title screen is a wide colorful bitmap kernel display.
ScumSoft even mentioned working on bus stuffing kernel techniques like SpiceWare.
I don't know if ScumSoft knows C programming to use the extra ARM cycles as a co-processor like SpiceWare and Joe Musashi.
This early ScumSoft demo of moving a night soft sprite around the bitmap was exciting to me, even though it has skip-a-line

Eggventure was done in batari basic and used RevEng's titlescreen bitmap framework, I didn't do it from scratch.

 

What I did at the time of that spritetest demo was rediscover flicker blinds in column flicker mode. The way it was coded doesn't leave much time to do other things in an actual gameplay. So I moved onto DPC+ for the extra umpf, however I didn't like the setup the stock framework has so I started recoding a new framework that focused on Bitmap engines and routines to augment such. I modified an older version of Stella to prototype the DPC+ changes that needed to happen since the Harmonys new core wasn't written yet.

 

I'll look through my coding backup and see how far I got on the actual project, I don't recall at the moment where I left off on it.

 

[edit]Looks like I left off coding the Harmonys new core using Keil. I was working out the cycle exact timing involved to have the 2600 run a display stub kernel from internal ram and have the ARM stuff the game display onto the bus during this time. Polling of A12 would occur only during certain windows to ensure we stayed synced up rather than all the time thus freeing up the ARM for pure C coded games.

Edited by ScumSoft
OCD
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Just got a Harmony Encore after getting tired of seeing broken stuff on the Atari Flashback Portable. Don't get me wrong, love the AFP because it is portable and plays a lot of stuff, but certainly not the ARM code of the Harmony cart. :D

 

So would love to see more of this or any other ARM projects.

Edited by doctorclu
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Sick, cant wait to see the progress!

 

Indeed. I nearly got Temporal Psychosis from this. It's like this should not be possible. And, yet, here it is. Then I was stuck back in the 70's dreaming of games like so, then seeing them come to the arcade in the 80's. Then fast forwarding to present day with Harmony and ARM DPC+ putting 1980's arcade material on 1970's hardware. Today, yesterday. The past was the future and today in the future the past is pulled forward on tech that got its base origins before any of the above happened. Today the future is the past and the past is the future it eventually became before the present deviated. And all of FAKED and made timeless with emulators running stuff. My head is spinning!! Gyrating worse than Gyruss!! Temporal Psychosis indeed..

Edited by Keatah
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Wow, Just Wow. That coming out of the VCS. The flicker isn't any worse than Asteroids.

Edited by Zonie

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On 1/24/2017 at 3:23 AM, Keatah said:

 

Indeed. I nearly got Temporal Psychosis from this. It's like this should not be possible. And, yet, here it is. Then I was stuck back in the 70's dreaming of games like so, then seeing them come to the arcade in the 80's. Then fast forwarding to present day with Harmony and ARM DPC+ putting 1980's arcade material on 1970's hardware. Today, yesterday. The past was the future and today in the future the past is pulled forward on tech that got its base origins before any of the above happened. Today the future is the past and the past is the future it eventually became before the present deviated. And all of FAKED and made timeless with emulators running stuff. My head is spinning!! Gyrating worse than Gyruss!! Temporal Psychosis indeed..

Well, actually 1980's material on 1970's hardware with the assistance of 2010's technology.

 

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Without looking deeper, I am almost certain this demo can be expanded to a full game on Unocart using ACE.

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Posted (edited)

a nolan bushnell vcs innovation award goes to the person or team who sees it through.  so this unocart using ace is a step above my Harmony cart?  Well for this game i'd be all in.  So basically instead of upgrading to Harmony Encore I'd upgrade to Uno?

 

this is my favorite vcs demo!

Edited by chewy

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Posted (edited)
This demo is very impressive!Using the extra resources of Harmony and Unocart there
is a possibility to finish this demo.
Edited by alfredtdk

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