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questions about parallax scrolling
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GHS
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PostPosted: Sat Jan 24, 2009 5:47 pm    Post subject: questions about parallax scrolling Reply with quote

The C-64 games Flimbo'sQuest and Hawkeye have what looks like 2layer parallax scrolling but the C-64 has 1 layer.
Can anyone explain in easy to understand detail on how it is dun, and can
the PCE do the same or better?
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Tomaitheous
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PostPosted: Mon Jan 26, 2009 4:33 am    Post subject: Reply with quote

From what I've seen for Flimbo's Quest, it's dynamic tile animation. Notice the foreground layer has hard vertical edges for the parts were the faux far layer scrolls by? The far layer is a series of pre-shifted tiles. You update the tiles with the new set for each scroll. Since there is a pattern, it only requires a small amount of updating as each instance in the tilemap reflects the change(instead almost a whole scroll screens worth of data).

It can get expensive (storage wise) depending on the complexity of the faux scroll. There are PCE games that do use this trick though. Some better than others. On the PCE, that trick is usually accompanied by sprites to make a more complex looking effect.

Btw - http://pcedev.blockos.org/viewtopic.php?f=5&p=96#p96 Wink I'll do a section on such tricks in the future.
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GHS
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PostPosted: Mon Jan 26, 2009 5:55 pm    Post subject: Reply with quote

Is this what wiki calls repeating pattern/animation method?
Games like Metalstorm and micromachines (nes) use this method but they look like a signal tile pattern scrolled in 8 directions, compared to Flimbo which looks like a large art piece composed of many tiles instead of a single repeated tile pattern.
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Tomaitheous
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PostPosted: Mon Jan 26, 2009 11:04 pm    Post subject: Reply with quote

Yes, those two games uses a simplified version of that method. NES doesn't have a lot of bandwidth for updating tiles, being a port based video ram system with only access during inactive display. So the the pattern is small like that.
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GHS
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PostPosted: Wed Jan 28, 2009 12:25 am    Post subject: Reply with quote

Can this method be used for 8 direction multi scrolling, or is it only for
horizontal and vertical scrolling only?
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Tomaitheous
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PostPosted: Thu Jan 29, 2009 7:59 am    Post subject: Reply with quote

It can be used for one, the other, or both. But the storage space is going to dramatically increase in size. For instance; a single repeating pattern inside an 8x8 tile is 8 frames for horizontal animation (8 pre-shifted/rolled frames). If you were to add vertical movement along with the horizontal movement, that's 8 more frames per 8 horizontal frames. So it would take 64 frames to have a free X/Y moving pattern for a single 8x8 cell. That's 2048bytes or 2k just for one tile set of animation Wink
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GHS
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PostPosted: Thu Jan 29, 2009 4:55 pm    Post subject: Reply with quote

So how many pixels/tiles big can you make the patter, and dose that depend on resolution, # of sprites etc?
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Tomaitheous
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PostPosted: Fri Jan 30, 2009 3:47 am    Post subject: Reply with quote

For the pattern size, technically as much as VRAM will hold (2000 tiles). I have a project that uses a 120x120 pattern. I don't do vertical scrolling and I use a special technique to save on memory. Remember, you normally need a revolution of the pattern for it to work. 8x8 pattern means one revolution is 8 frames, but for a 120x120 picture I would normally need 120 frames. That would take up 865k. The method I employ only requires 115k and 8 frames. And it doesn't really take anymore resource to do it, but the method overly complicated.
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GHS
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PostPosted: Fri Jan 30, 2009 4:09 pm    Post subject: Reply with quote

OK? getting of topic here, can we get back on it!?

Are there any games on the PCE that use this method, either simple or complex?
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Kaminari
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PostPosted: Fri Jan 30, 2009 5:18 pm    Post subject: Reply with quote

(It's a spam bot.)
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Tomaitheous
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PostPosted: Sat Jan 31, 2009 3:57 am    Post subject: Reply with quote

GHS wrote:

Are there any games on the PCE that use this method, either simple or complex?


Only a few have X and Y pattern scrolling. I think Star Parodia does x/y pattern for one level, but it's pretty basic. Lords of Thunder uses horizontal shifted pattern in a few areas. The water level with the parallax scrolling water, is preshifted tile animation. The desert level too, so that the large enemy can be moved independent of the parallax sand.
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GHS
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PostPosted: Sat Jan 31, 2009 4:52 pm    Post subject: Reply with quote

I found some games that use this method.
DraculaX, ShapeShifter, NinjaSpirit and NinjaGaiden.
NinjaGaiden's backgrounds are large art pieces that are supposed to stay still while the foreground scrolls, but the BG looks jerky when you move. Why is that? (look it up on You Tube)
As for NinjaSpirit the 2nd levels tree branch leaves are not hard vertical edges and there not sprites, so how dose that work?
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Tomaitheous
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PostPosted: Mon Feb 02, 2009 3:14 am    Post subject: Reply with quote

GHS wrote:
I found some games that use this method.
DraculaX, ShapeShifter, NinjaSpirit and NinjaGaiden.
NinjaGaiden's backgrounds are large art pieces that are supposed to stay still while the foreground scrolls, but the BG looks jerky when you move. Why is that? (look it up on You Tube)
As for NinjaSpirit the 2nd levels tree branch leaves are not hard vertical edges and there not sprites, so how dose that work?


The 2nd or 3rd level in Gradius 2. The second layer scrolls while there's a destructible first layer. It's still a pre-animated tileset, but it looks great and very convincing.

As far as Ninja Gaiden; they just scroll the screen and when it scrolls 8pixels, then the re-update the map to align with tiles. It's not pre-shifted or animated at all. It should be, but it's not. Look at Schibibiman 3 . That's what Ninja Gaiden should have looked like. A set of pre-shifted tiles and then updates to the map when they expire. Rinse and repeat.

Ninja Spirit 2nd level is just dynamic tiles. Whether it's realtime overlaying of the leaves on those BG tiles or prerendered, I'm haven't looked that far. It's probably real time to save space. It's more than 1 tile wide, the repeat pattern is also wider than 1 tile, and there's vertical movement too which would eat up a lot of space in rom. I'd say it's a good chance that it's overlayed in real time (would explain the slowdown in that level).
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GHS
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PostPosted: Mon Feb 02, 2009 7:11 pm    Post subject: Reply with quote

Prerendered? do you meen the effect used on killer instinct and Dracula sega CD, can the PCE do that?

And what is realtime overlaying?
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PostPosted: Thu Feb 12, 2009 11:15 pm    Post subject: Reply with quote

GHS wrote:
Prerendered? do you meen the effect used on killer instinct and Dracula sega CD, can the PCE do that?

And what is realtime overlaying?


Prerendered just means the image or tile or sprite was rendered before hand. It doesn't necessarily mean computer CG. Sapphire for the PCE ACD uses prerendered morphing animation and such. Lots of it.

Realtime overlaying is just the opposite. The CPU takes a layer of graphic data and manually/logically overlays it onto another layer of graphic data. Early 90's PCs had no hardware for sprites and multiple BG layers. The CPU manually overlaid all overlapping graphic data. It's not a fast process and on the PCE, it's not really optimal. But it can and does save a lot on graphic storage compared to prerendered data.
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