Is there a name for the graphical effect 2D racers used?

[Mobius]

I've been playing a lot of Top Gear 2 lately, and this question popped into my mind. It's pretty trivial, but it got me wondering. Older 2D racing games like Pole Position, Out Run, Rad Racer, and Top Gear, all use a very similar and distinct graphical effect to simulate driving. Is there a term for that effect? There are top-down racers, Mode 7 racers, 3D racers, but what is there a term for this particular group?

[Icarus Moonsight]

I'd would think it's just a variation of parallax scroll. I'm not sure either so, good question. :)

[kedawa]

Just because it's not polygon based doesn't mean it's 2D.
As far as the graphic technique, I'm not sure. Maybe some kind of vector rasterization or line scrolling?

[Leo_A]

Sprite scaling

[Wraith Storm]

Sprite scaling

This is what I always refered to them as.

They use "Sprite Scaling" to simulate 3D. The objects are far away and then they scale bigger and bigger as you get closer. This includes flag poles, scenery objects on the side of the road and the other racers you are competing against.

I recently got Jaguar XJ220 for the Sega CD. I assumed it would have taken advantage of the Sega CD and used a mode 7 effect or something cool like that, but nope, its a standard (although great!) sprite scaling racer. Although it does have a TON of sprite scaling being tossed around so maybe it does use a bit of the Sega CD power.

[j_factor]

This is what I always refered to them as.

They use "Sprite Scaling" to simulate 3D. The objects are far away and then they scale bigger and bigger as you get closer. This includes flag poles, scenery objects on the side of the road and the other racers you are competing against.

I recently got Jaguar XJ220 for the Sega CD. I assumed it would have taken advantage of the Sega CD and used a mode 7 effect or something cool like that, but nope, its a standard (although great!) sprite scaling racer. Although it does have a TON of sprite scaling being tossed around so maybe it does use a bit of the Sega CD power.

It does and it doesn't. "Mode 7" is an SNES only thing (the seventh mode of its VDP). Mode 7 actually has nothing to do with sprite scaling, it's purely scaling and rotation of a background. Sprite scaling can be done in software, but isn't always used. For example, F-Zero doesn't actually scale its sprites, it just redraws them at certain distances. Sega CD is one of very few systems with proper sprite scaling in hardware (I think 3DO has it too), in addition to "mode 7 style" background scaling/rotation. Jaguar XJ220 uses the former but not the latter. Note that it's a conversion of an Amiga game, and Amiga doesn't have any scaling hardware at all. But the Sega CD version is a bit graphically enhanced over the Amiga version.

Most people use the term "sprite scaling" for any sprite-based, rear-view game, even if it doesn't technically scale sprites. I think the first rear-view type game was Turbo (though you could make an argument for Night Driver), and the first game with true sprite scaling was Blaster. Not sure, though.

[Ed Oscuro]

Double post!

[Ed Oscuro]

Hot dang, what I was looking for was the second hit on Google.

Behold: http://www.gorenfeld.net/lou/pseudo/

Which effect do you mean?

The roads are described at the link above.

Rotation and scaling are implemented with tilemaps, and there's a brief, easily understood introduction to and history of them here (http://mamedev.org/devwiki/index.php/Tilemaps). You don't get a technical description of how rotation and scaling is implemented, though.

In brief: Tilemaps are just what they sound like, but often with the potential of running enhanced effects on them like scaling, rotation, giving the impression of 3D surfaces, and so on. The SNES wasn't incredibly powerful but its tilemap hardware seems quite flexible, though I'm not certain about the details.


Just because it's not polygon based doesn't mean it's 2D.
Whoa dude, that's a deep philosophical statement.

Aside from voxels and sphere trees, though, I can't think of any 3D system that doesn't use polygons in a visual capacity (and of course polygons are great for defining the relationship between objects, or the boundaries of objects, even when they aren't seen explicitly). Polygons are just sets of coordinates...in 2D space. You can call DOOM's walls polygons, even though they can't be transformed in all the usual ways you would in a 3D space. Bungie called Marathon's (DOOM-type game) walls polygons.

[jb143]

Are you talking about the way the background(track) moves? Or the cars move? Or both? The cars generally use bitmap scaling as others have said. The background can be done several different ways. One thing they do sometimes is to have a portion of the color palette with increasing chades of a color and draw the ground or track with this so it gets darker as it goes back then repeats. Or just have it alternate. Then by rotating through the color palette you simulate movement with very little computation power.

An example is the track and red/white border on Hang-On...
http://www.klov.com/images/11/1181242121359.png

To actually draw the track where it looked 3D, on technique was to draw a straight line from the edge of the screen to where the edge of the track would be in the color for the ground. Then the color of the track, then the ground again. For each line of the screen drawn as you get closer to bottom of the screen, you draw the track wider so it looks like it's gettign closer to you. Then by varying where you draw the track colored line, you can simulate the track curving as you drive and turn. I can't think what the technical name for this is but I think it's in an old game programming book I have at home that I can look up tonight.

By combining this with the above palette rotation technique and sprite scaling for the cars and other objects you can do a pretty good simulation of a 3D scene with no 3D calculations and not much CPU power.

Edit---
I just checked out Ed Oscuro's link above and it pretty much went into much much greater detail on what I just said. Oh well...

[XYXZYZ]

I call it 2D3D. :)

[Mobius]

Thanks Ed and jb, that's some good info! I was specifically thinking about the effect that creates the road, but as others mentioned, the sprite scaling for the objects and cars is a good point. It makes sense that the overall illusion is created by the combination of the two different techniques.

I guess I'm mainly looking for a term that would let me group all these similar games together as a genre. I guess I'll go with "pseudo 3D" like the author in Ed's link.

The Gallery in Ed's link is interesting... I wonder if Road Rash on the 3DO really does use this technique. If it does, then it's the most convincing I've ever seen -- I thought it was done with polys!

[Gameguy]

Only pseudo 3D covers much more than the specific style you're talking about, from what I could find it's specifically called "linescroll".

http://en.wikipedia.org/wiki/2.5D


Pole Position by Namco is one of the first racing games to use the trailing camera effect that is now so familiar. In this particular example, the effect was produced by linescroll-- the practice of scrolling each line independently in order to warp an image. In this case, the warping would simulate curves and steering. To make the road appear to move towards the player, per-line color changes were used, though many console versions opted for palette animation instead.

[Game Freak]

It does and it doesn't. "Mode 7" is an SNES only thing (the seventh mode of its VDP). Mode 7 actually has nothing to do with sprite scaling, it's purely scaling and rotation of a background. Sprite scaling can be done in software, but isn't always used. For example, F-Zero doesn't actually scale its sprites, it just redraws them at certain distances. Sega CD is one of very few systems with proper sprite scaling in hardware (I think 3DO has it too), in addition to "mode 7 style" background scaling/rotation. Jaguar XJ220 uses the former but not the latter. Note that it's a conversion of an Amiga game, and Amiga doesn't have any scaling hardware at all. But the Sega CD version is a bit graphically enhanced over the Amiga version.


Where would Super Mario World 2 fall in here? is that hardware or software? Isn't it the Super FX 2 chip?

[Baloo]

Sprite Scaling seems about right.

But what do you mean by proper sprite scaling J_factor?

[Arkhan]

I call it "into screen". Whether its done with sprite scaling/mode 7 (which used regular sprites on scaled backgrounds), or vector graphics (like tempest!) its still "into screen" as far as my eyes are concerned.

:-D

[jb143]

Well, I looked it up in my books and it only described the techniques, not what they were called. And I agree, pseudo 3D is a term used to describe a wide range of techniques. The genre of games would still be "trailing camera racing simulation"...or something to that effect.

[savageone]

If I recall correctly the proper scientific term for this is "2.49D".

Indeed.

[Ed Oscuro]

I guess I'm mainly looking for a term that would let me group all these similar games together as a genre. I guess I'll go with "pseudo 3D" like the author in Ed's link.
It works, although as jb writes, it's not really specific.

You could just explain what it is: "simple non-polygonal perspective-corrected road visual simulation."

"2.5D" is inspecific, and so...uncool, unless you're talking about Wolf 3D style engines.


The Gallery in Ed's link is interesting... I wonder if Road Rash on the 3DO really does use this technique. If it does, then it's the most convincing I've ever seen -- I thought it was done with polys!
It kinda looks like they use graphical patterns instead of just flat-fill lines in the road tilemap, and bumped up in resolution over even arcade racers from the time. Polygons would probably lead to seams. It does make me wonder what the requirements would have been to get this working on arcade hardware, or (if that wasn't a problem) why the arcade developers didn't do anything quite as refined.

[tomaitheous]

Heh, someone linked Louis' page. He'll be happy :)

First off, I think calling it 2.5D is misleading. That term really didn't stick/apply until the PSX era. It means a 3D environment with a fix camera to simulate a 2D play field. Like Dracula X remake for the PSP. Full 3D environment, fixed camera and limiting game controls forcing it into 2D gameplay environment. Klonoa is a good example of 2.5D.

Pseudo 3D is what it was called BITD that I remember. It's a 3D environment built with very limiting factors, objects, and special fx.

For those old school 3D racers, most were done with linescroll/H-Int effects. You can make hills and bends with it. You can scale vertically with doing an interrupt on every scanline and adjusting the Y scroll value, to make hills and bends. Quite a few consoles could do this, almost all arcades could do this, some home computers could do this, PC's could not do this. On early/slower home computers, the method for animating the road isn't as clear/exact as it was for consoles. Early NES racers didn't even use H-Int's for linescroll. It couldn't without a special mapper. Instead, it just had predrawn frames for the curves/turns, no bumps or hills, and used palette animation/cycling to give the effect of movement.

As far as objects, systems that didn't have scaling - had prerendered/scaled frames in memory (whether in rom or prebuilt to ram before the stage starts). Though, this took up memory. So you tended to have less number of scaling transitions in Z movement.

[j_factor]

Where would Super Mario World 2 fall in here? is that hardware or software? Isn't it the Super FX 2 chip?

Yes, it's the Super FX 2 chip that does all that fancy stuff, so it is in hardware for that game. I don't really know anything about how that chip works though.


But what do you mean by proper sprite scaling J_factor?

It's kind of hard to explain. In Space Harrier for arcade, the hardware has sprite scaling as a built-in function. The 32x hardware does not have sprite scaling, but its port of Space Harrier accomplished sprite scaling through software. The SMS version doesn't scale at all. In fact, IIRC the SMS version doesn't even use sprites aside from the player character, and instead renders the entire rest of the game as a background image which it redraws every frame.

Maybe that's not the best example. Look at F-Zero. See how the enemies seem to "jump" in size? That's not sprite scaling. Each enemy has 6 (or however many) sprites associated with it; each sprite is a different size, and each one is used at a certain range of distance. During gameplay, the sprites swap out accordingly.

[jb143]

Heh, someone linked Louis' page. He'll be happy :)

First off, I think calling it 2.5D is misleading. That term really didn't stick/apply until the PSX era. It means a 3D environment with a fix camera to simulate a 2D play field. Like Dracula X remake for the PSP. Full 3D environment, fixed camera and limiting game controls forcing it into 2D gameplay environment. Klonoa is a good example of 2.5D.

Pseudo 3D is what it was called BITD that I remember. It's a 3D environment built with very limiting factors, objects, and special fx.

I know this came up before, but I always heard of any "3D in 2D" technique labled as 2.5D as well...long before it's common useage of 3D engine used to simulate a 2D game(usually in reference to ray-casting though). I've probally heard Pseudo 3D more for the racing games though.

The book I have did mention using multiple images for different turns in the track as well, which seemed kinda lame. I've seen games for calculators that had more impressive tracks than that. Like this one I had on my HP-48GX...
http://i260.photobucket.com/albums/ii12/jeremy_burk/crazycar.gif

While not seen in the older games, something else that they did in the CD-ROM era, was to use pre-rendered vidoes for the background and sprite scaling or some other technique for the cars. Megarace for example.

[kedawa]

Technically, no video game is 3D, so the terminology is just jargon.
The closest thing we have to 3D is stereoscopic 2D, which is just an optical illusion.
It would be nice to have an agreed upon set of terms to describe the various techniques used to simulate depth on a 2D plane, but it looks like we're out of luck.

[jb143]

Technically, no video game is 3D, so the terminology is just jargon.


Wasn't there some handheld LCD games that stacked the screens to create, not just simulate depth? That's probally the closest to real 3D we have.

The difference though between early and modern "3D" games is that the modern ones actually use 3 dimensional math and store the data in 3 dimensional data structures. So while it's still being displayed on a 2 dimensional screen, the game itself is 3D.

[VincentGR]

I have seen this technique on many machines and I call it line scrolling :roll:
Some machines have hardware to do this I think, but i have seen it on Amiga with great success.
Some Amiga games that using it are Shadow Fighter, Elf mania and Lionheart. I believe that on Amiga it is done by software... right?