About Taito "screen edge rubbing"

[BIL]

Something I've wondered about for a while (this may seem bizarre or inconsequential, and for that I apologise! Not many other forums I'd ask this on, and from a quick search I don't see it already addressed).

Has anyone else noticed the way Taito shooters tend to factor in "friction" against the sides of the playfield, causing your ship to slow down if you press against the screen's edge while moving? Rayforce, Raystorm, Metal Black, Darius Gaiden and Gekirindan are the ones I've personally noticed.... G-Rev's (obviously Taito-related) Border Down and Under Defeat do it too. Interestingly Kamui (which has countless artistic & gameplay references to the Ray series) is yet another. I assume, given how many examples I've already seen, that there are a few other Taito-related shooters that also do this. It's a tiny detail, but occasionally a factor for me (sometimes it comes in handy for especially minute dodges; other times it's an annoying hazard I have to consciously avoid, or get killed by attacks I'd normally have sped past).

What I was wondering is, has this odd feature ever been acknowledged by either Taito's developers themselves or players? And has anyone seen it present in shooters by other companies (for all I know it far predates Taito)? I just find it interesting that such a miniscule detail persists through G-Rev's continued work and even an unrelated game like Kamui.

[Randorama]

Darius (the first chapter) has this mechanic has well. You can't enter the whole of the third screen (right one), and you move quite slowly if you are on the edge of this zone. I believe that it is an old mechanic, though, Juno First for instance has a similar effect when you approach the upper edge (but is a given of the perspective I suppose: Konami (1983)).

Dunno about companies, but Kyukyoku Tiger 2 has a similar effect has well (Takumi (1994), supported by Taito). Of course personal comments by programmers are a bit beyond my knowledge . Doesn't Gradius have a similar feature, as well?

[BIL]

Ah, I suspected it would have appeared in an earlier Darius somewhere, given that series' stature in Taito's catalog. That's also interesting to know something similar is in Kyukyoku Tiger 2, given the Taito connection. I don't think I've seen it in the Gradiuses or R-Types I've played (most of the original games except for Gradius IV and R-Type Final), though I've not gone back and checked recently (I was looking out for it a few months ago).

It's an odd little feature, given the obviously deliberate effort that goes into creating a game (particularly minutely detailed ones like shooters). It's not exactly useful, and is even hazardous at times, yet it's apparently established enough that it was even translated into 3D games like Raystorm. Kamui basically paid tribute to it along with its countless Ray references.

I wonder if it was some kind of attempt at what Cave ended up doing with their slowdown mechanic. Or maybe it's just the ship's diagonal movement speed being displayed on a straight path... even if so, it's strange that it'd constantly recur where most shooters seem to stamp this out (so that you only get vertical / horizontal movement speed along the edges). Maybe it's kind of a deliberate mistake on the coders' parts.

[nimitz]

wow, never knew that!

i just checked this out with Rayforce, Grid Seeker, Gekirindan, Darius Gaiden and Metal Black...

and its there in every one of them, and the speed difference is always the same wich is 3/4 of full speed when ramming in the side of the screen and moving around. this is definitly not a bug or a glitch (maybe it was when it first apeared though)

I think it shows very well how many little details like this we probably don't know about yet.

and Kamui including that "feature" is just awesome.

[sfried]

Iridion II has this as well, although I guess it's justified, considering there are walls.

[ReKleSS]

Heh, that's just geometry. You can move in the cardinal directions at a certain speed. If you're moving diagonally, one of two things can happen:

-You move horizontally and vertically at the normal speed. Your actual speed is sqrt(2)*normal speed.
-You move at 1/sqrt(2) of your normal speed horizontally and vertically. Your actual speed is the same as when you're not moving diagonally.

I believe some Raizing games take the first approach - if you move diagonally, it feels like you're moving faster than normal. It feels like friction because if you're against the edge of the screen you lose the horizontal component of your movement, so your absolute speed is lower.

[BIL]

I see, many thanks for the detailed explanation. Perhaps this seemingly global quirk is a case of Taito taking an "ain't broke, don't fix it" approach. I'd never thought about differences in handling between developers' shooters, to that extent.

[nimitz]

Heh, that's just geometry. You can move in the cardinal directions at a certain speed.

edit: I stand corrected. After looking it up and testing a bit seems that its just different mechanics, earlier games tend to have the same total speed while some games have the same linear speed (in the end faster) while moving diagonally..

[worstplayer]

Heh, that's just geometry. You can move in the cardinal directions at a certain speed.

Hmm no, when you press say down + right in a shmup you move at the same horizontal speed than if you press right only its always been that way....


As I said the first occurence of this probably happened because the programer used some wierd calculations for the ship speed near the edges(or the third screen if it indeed started with the first darius). Then taito kept it on purpose since its actually a nice little feature.

Wrong. You usually move at the same TOTAL speed. Both horizontal and vertical speed are slower. There are some exceptions of course. (Garegga and other Raizing games, some horizontal shooters)

EDIT: LOL, just noticed my game slows down on borders too.

[nimitz]

I did some testiong and there seem to be no real consistency.

Taito games always have friction
Konami games always have friction
Cave games always have friciton (even ibara)
Psikyo games always have friction

Seibu games never have friction
dooyong games never have friction

Early capcom game don't have friction
the later ones do (91-96 era)

mars martix doesn't have friction
gigawing does.

barkraid,garegga,batrider don't have friciton
mahou daisakusen does.

Most toaplan games dont have friction
batsugun does.

Turbo force doesn't have friction
the other Video system games do

[j^aws]

...
I wonder if it was some kind of attempt at what Cave ended up doing with their slowdown mechanic...

By "slowdown" mechanic by Cave, are you referring to alternating between fast/ slow speeds using an action button? If so, then this was done as early as Solar Fox (circa 1981), an arena shoot-em-up...

Re: Speed

I find slight variations depending on how my display is setup for stretching horizontally/ vertically, distorting 'distances'... Unit pixels traveled per unit time (not at edges) is still the same for most cases, no?

@ nimitz

Are you referring to "friction" at screen edges only?... Something like Raiden III has friction when you move directly 'down', i.e. it's distinctly slower than moving directly 'up'...

[BIL]

By "slowdown" mechanic by Cave, are you referring to alternating between fast/ slow speeds using an action button? If so, then this was done as early as Solar Fox (circa 1981), an arena shoot-em-up...

Yep! That's the mechanic. Jesus, it's older than I am. Cave is really just a reference point for me there, I can imagine how far back in time some of this genre's features go.

With ReKleSS' post the Taito sort seems more like a tolerated side-effect, which can have a similar (if limited) benefit with careful use. Nevertheless I can't imagine it went un-noticed in testing, with it giving the player a certain advantage in otherwise very nasty situations like Rayforce's high-rank spread attacks.

[nimitz]

@ nimitz

Are you referring to "friction" at screen edges only?... Something like Raiden III has friction when you move directly 'down', i.e. it's distinctly slower than moving directly 'up'...

Well friction is not really the right term

I actually mean costant cardinal speed. even when moving diagonally. a game like 1942 (capcom) has constant left/right ship speed no matter if you are moving up or down.

but in a game like Gradius (arcade) you will move slower forward if you are moving up or down at the same time. Thats what I call friction because its easier to see it and more useful on the screen edges.

also, the difference between lateral and forward/backward speed is irrevelent.

[j^aws]

^^ Okay, I think I get what you mean.

I Just popped in Raiden III to see if 'speed' is an optical 'illusion'... Okay I'm not convinced now it moves "slower" directly down, than 'up'... roughly timing it seems the same. The auto-scrolling upwards gives an impression of moving faster; and moving 'back' gives the impression of 'friction'...

[j^aws]

...
With ReKleSS' post the Taito sort seems more like a tolerated side-effect, which can have a similar (if limited) benefit with careful use. Nevertheless I can't imagine it went un-noticed in testing, with it giving the player a certain advantage in otherwise very nasty situations like Rayforce's high-rank spread attacks.

Just quickly checked Rayforce, and it behaves the same as Raiden III, AFAICS, with the same 'optical' illusion... Perhaps RekleSS can clarify; but I see the two points mentioned in that post as meaning the same, assuming a square pixel...

i.e. Speed is distance traveled per unit time. The diagonal distance traveled for a unit square pixel is sqrt(2); the straight distance being 1 (Pythagoras)...

EDIT: Okay, I wasn't pressing hard enough against the edge in Rayforce, I feels slower moving up now.
_________________

[BIL]

Yeah, it's definitely present in Rayforce. It's a pain in the ass actually, if you instinctively retreat to the very bottom of the screen like I do when things get hectic. I had to seriously unlearn that behaviour, it's a recipe for disaster in that game.

[ReKleSS]

Don't assume your horizontal speed is always the same as the vertical. In Raiden, I believe the P1 ship moves faster vertically and the P2 moves faster horizontally. In Raizing stuff the speeds are scaled to screen width and height - if you start in one corner and move out diagonally, you'll end up in the other corner.

If you want to measure stuff more carefully try frame stepping in mame. Hit p to pause, then shift+p to advance one frame. You can clearly how far you move per frame.

[spadgy]

I'm still a little confused. Is the 'friction' just an illusion as you don't have diagonal movement, or is it actually in place?

I'm sure I remember various Amiga shooters with 'sticky' edges...

[j^aws]

Don't assume your horizontal speed is always the same as the vertical. In Raiden, I believe the P1 ship moves faster vertically and the P2 moves faster horizontally. In Raizing stuff the speeds are scaled to screen width and height - if you start in one corner and move out diagonally, you'll end up in the other corner.

If you want to measure stuff more carefully try frame stepping in mame. Hit p to pause, then shift+p to advance one frame. You can clearly how far you move per frame.

Thanks. I've now got a clear picture of the 'velocities' involved that revolve around a unit pixel (locally) and aspect ratio (4:3; 3:4; 1:1 etc). What threw me was your original sqrt(2) diagonal scaling; I can see that varying though...

I'm still a little confused. Is the 'friction' just an illusion as you don't have diagonal movement, or is it actually in place?

I'm sure I remember various Amiga shooters with 'sticky' edges...

"...you don't have diagonal movement..."

At the edge, when pushing diagonally and upwards for example in Rayforce: Your digital input is diagonal; but the screen edge restricts you to just moving upwards. If you think of your general diagonal velocity being the sum of your horizontal and vertical velocities; then at the edge, it's like the coders forgot to add the horizontal velocity component (because you're only moving vertically at the edge); thus reducing your overall velocity (like friction acting at the screen edge)... Does that make it any clearer or worse? ;P

EDIT: Or were you referring to 'illusion' not at the edge?

[BulletMagnet]

Well friction is not really the right term

Time to fire up the ol' glossary again, methinks.

[spadgy]

Cheers Jaws. Perfect explanation for my simple mind. I'm up to speed now!

[nimitz]

I just checked the Glossary and there is no such thing listed.

a good (and short) way to call it would be: Full (faster) vs Corrected (slower) diagonal speed.