Wavy Navy Is it possible??

[neotokeo2001]

One of my favorite games is Wavy Navy for various computer platforms.

Looking at the screenshots, Would a version be possible on the Atari 2600??

 

 

The waves have a constant rolling effect from left to right, I think that would be the biggest problem.

[Out_of_Gas]

If anyone can do it, you can.

[Thomas Jentzsch]

Depends on how smooth you want to have them. If using blocky playfield graphics is acceptable, then there should be no problem with the waves.

[neotokeo2001]

If anyone can do it, you can.

 

Nope. It's beyond me, I'm only a hacker not a coder. Maybe someday.

[neotokeo2001]

Depends on how smooth you want to have them. If using blocky playfield graphics is acceptable, then there should be no problem with the waves.

 

I don't know if a blocky wave would kill the gameplay (too jittery?). Maybe just a static picture of a wave??(but that would be blocky too) Another idea is to break the wave into 3 sections (left. center, right) and just have each section rise and fall. This may be the best solution.

[Nukey Shay]

Nonesense, it doesn't need to be that limited. The 2600 has 40 horizontal pixels. It looks pretty choppy in the example below, but if each "step" were limited to 1 pixel in height (as opposed to 1 to 8 in this pic), it would look less so (and take less memory).

 

This example uses 99 bytes per frame to store the playfield data. If the waves were rolling at 2 pixels per step (total of 12 frames), that could fit into 1 bank easily...each page of memory holding an odd and even frame #.

[neotokeo2001]

Nonesense, it doesn't need to be that limited.  The 2600 has 40 horizontal pixels.  It looks pretty choppy in the example below, but if each "step" were limited to 1 pixel in height (as opposed to 1 to 8 in this pic), it would look less so (and take less memory).

 

This example uses 99 bytes per frame to store the playfield data.  If the waves were rolling at 2 pixels per step (total of 12 frames), that could fit into 1 bank easily...each page of memory holding an odd and even frame #.

 

Thats way more detailed then I thought was possible. With that type of wave is it still possible to have the same number of enemies?

[Nukey Shay]

The wave doesn't matter, since it's made of playfield GFX which is just fetched 3 bytes per scanline and then mirrored to the other half of the screen. Now that I think of it, the number of bytes can be further trimmed to 30 for each frame...since you are loading 3 bytes at a time and you could space the waves out so that 20 pixels exist from crest to crest. A seperate data table dictates how many scanlines each group of 3 bytes use on the screen (from 1 scanline to 8 ).

Not sure about the number of enemies tho. I reduced the number of them horizontally to 7 (which is what it is in Galaxian).

[Nukey Shay]

Galaxian...hmm...how about hacking Galaxian to take playfield GFX into account? I dunno how much prospect there is for free cycles/ram/rom that Galaxian would allow, but there must be quite a bit devoted to the attract mode. The playfield would consume 600 bytes for the waves if they are scrolling 1 pixel at a time (300 if 2 pixels at a time), a dozen or so for the scanline counter values, and 3 bytes of ram to put the playfield data in prior to jumping to the display.

[neotokeo2001]

That's all beyond me.

 

I would love to see it happen one day.

[Nukey Shay]

The idea is that Galaxian already uses a small amount of processor time to display the borders of the screen (and the method above uses slightly more). If there is cycle time in the kernal being wasted, it should be possible.

 

Getting all of the free space, that's the real trick. But I've done it before :wink:

[NE146]

Getting all of the free space, that's the real trick.  But I've done it before :wink:

 

Yes you have

[Nukey Shay]

If you could live without the 4 pixels on the outer edges, that would reduce the number of bytes to 2 each. A smoothly (1 pixel, that is) rolling wave consisting of 10 levels of height would consume 400 bytes...200 if it's rolling 2 pixels at a time (which would get it to fit on a single memory page). But scrolling 2 pixels might look too choppy...so I think that it would be better to consider 2 pages (odd frames grab from 1 page, even frames from an adjacent page).

[Thomas Jentzsch]

How about rolling the waves by simply shifting the bits?

 

And if you can accept some symmetrie you would only need 3 bytes/row which only have to be set once/row (using non-reflected playfield). Check e.g. Laser Gates, Cruise Missile (or Cave1K for examples.

[Nukey Shay]

Yeah...but time might be a factor with enemies dipping below the wave crests. ROL/ROR Worked OK in simpler kernals like Breakout ...though I understand that Defender also shifts bits for its cityscape.

[ATARI TROLL]

Don't tease with pics Post the bin damnit!

 

Cheers

[neotokeo2001]

Don't tease with pics Post the bin damnit!  

 

Cheers

 

Just planning to see if it is possible. No work has started on it that I know of.

I would love to see someone attempt it.