Games with pixel screen scrolling?

[nippur72]

can you name VIC-20 games that use screen scrolling at the pixel level (VIC's screen-offset registers).

I can only think of one: Salmon Run.

Any other?


P.S. howdy to the forum! it's a long time I've been away from here

[beamrider]

note sure about original games from the 80s

some contemporary games come to mind..

Cheese & Onion
Pulse
Victragics Kickstart (1/2 char)

[hasseapa]

There are quite a few from the 80s. While their scrolling bg often is rather sparse and only a small part of the screen, they are very often part of a parallax effect.

Quadrant (1983). Unexpanded Moon Patrol clone. Lower layer/row moves at 4 pixels/step, middle layer at 2 pixles, upper layer 1 pixel.

Moon Patrol (1983). Two layers.

Choplifter (1982). Tanks scroll faster than houses & hostages. Also a nice parallax effect at the crossing of the border.

Jungle Hunt (1983). Overlaying parallax in the sea/river level! The faster layer moves at 4 pixels, the slower at 2 pixels.

Spiders Of Mars (1982). Super smooth 'wireframe' mountains. 50/60 fps?

Regarding contemporary games. Let's not forget Misfits' precursor to Cheese & Onion - Super Starship Space Attack. Full screen vertical scrolling with nice parallax effect.

[Ola H]

Polaris (1983)

[DarwinNE]

I tried to achieve a sub-char vertical screen scrolling in my Cavern Explorer (2018):

http://sleepingelephant.com/ipw-web/bul ... 2&p=102571

I'm not fully satisfied of it, I think the code can be made more efficient, but it works reasonably well.

[nippur72]

I tried to achieve a sub-char vertical screen scrolling in my Cavern Explorer (2018):

very nice game! I was just thinking of making a game like this

[DarwinNE]

very nice game! I was just thinking of making a game like this

Thank you!

[pixel]

Pulse

Not quite. It's actually recalculating the charset for each frame, thus making things much more straightforward.

[Ivanhoe76]

Skyhawk even if i think it's 2 pixel scrolling

[beamrider]

I've just discovered "Mountain King".

https://www.youtube.com/watch?v=tAItz1ig6B0

I thought Cheese & Onion was the only game to have 4-way smooth scrolling, but this seems to have it as well, albeit with a more repetitious background.

In addition It also has a fixed panel at the bottom which misfit said he found too difficult to do in C&O.

[beamrider]

Intrigued, I did a bit of digging.

Mountain King doesn't appear to be update the HSCROLLPOS register @ $9000 so I am guessing it's shifting a few defined pairs of characters to achieve the fine scrolling illusion. As can be seen here, this works well on a repeating/constrained background, but not to well for arbitrary graphics IME.

MK does update $9001 for the much simpler vertical scrolling. I'm guessing that the static potion at the bottom is re-rendered at the pixel level on every change of vertical position otherwise I've found that it judders up and down, since $9001 is latched during the fly-back, and any changes during raster splits have no effect.

[nippur72]

Mountain King doesn't appear to be update the HSCROLLPOS register @ $9000 so I am guessing it's shifting a few defined pairs of characters to achieve the fine scrolling illusion. As can be seen here, this works well on a repeating/constrained background, but not to well for arbitrary graphics IME.

that's strange, how can you use shifting when you have different colors without color clash? (e.g. the cyan stairs and the red ground). To me it seems $9000 horizontal scrolling at work. Is it moving 1-pixel steps or two? (I'm unable to step frame by frame in youtube)

[beamrider]

I put a watch on $9000 in VICE and it never fired.

[nippur72]

I put a watch on $9000 in VICE and it never fired.

you are absolutely right. $9000 isn't touched at all, and if you force $9005 to $ff you see how only certain tiles are moved/shifted. The cyan stair and red ground I guess it's done with multicolor.

Very very remarkable!

[beamrider]

So you can - even more so if you slow it down to 10%.

As I already mentioned, you can now see that the bottom static area has unwanted vertical juddering when it scrolls up/down, so they must be offsetting the rendered text characters to compensate.