idea for rotating large tile-map-like objects

[psycopathicteen]

Use a bunch of 32x32 sprites, arranged in a rotating grid. Each 32x32 sprite will represent a rotating 22x22 tile, but spaced 21 pixels apart so there are no cracks or holes between tiles.

[Drew Sebastino]

What now? Are you looking to do something like the title screen of After Burner II, except for no sprite scaling? If you are actually making it a textured surface with now holes in it, you won't be able to "tilt" it much before it starts to look crazy. What are you actually trying to use this for?

[psycopathicteen]

I was thinking about having a boss bust a wall down.

[tokumaru]

Like this?

EDIT: Here's a smoother hacked version.

[Sik]

Busting down a wall sounds more like this.

[tepples]

EDIT: Here's a smoother hacked version [of Sonic 1's special stage].

Wow, the hacked version is awesome, coming close to mode 7 of Cameltry/On the Ball.

[tokumaru]

Busting down a wall sounds more like this.

Cool, I didn't know Ristar could do that.

Anyway, I was replying to the general rotating grid idea, not the specific wall busting example.

Wow, the hacked version is awesome

Interestingly enough, it seems that the code for the smoother rotation was in the ROM all along, and it can be enabled with a very minor modification. I wonder why they went with the choppy animation if they could have this.

[Sik]

Because there aren't enough sprites for the walls to not look like crap while rotating - that hack is using double the amount of sprites for them I think (and even then it's noticeable, although if they used rounding when determining the angle to use it'd be less noticeable). Doesn't sound like much, until you realize that was right in the wake of mode 7 so any hint that it wasn't a true rotating map would have made Sega look really bad.

Also apparently the controls play a part on it too, although let's face it, those Special Stages are hell to control smooth or not =P

[Stef]

The hack only remove a single asm instruction to get the smooth rotation up so the number of sprites is exactly identical to the original. Honestly the smooth rotation looks far better imo and even if they changed it for gameplay reason i believe they should have keep it smooth anyway, as you said control is crap even in the original, it probably does not make a big difference here.

[Sik]

I mean the specific hack shown in the video, I know that to get the smoothness you only need to remove an AND instruction (or replace its operand with $FF, meaning it's doable with a Game Genie code if you want).

[Khaz]

I'm blown away that that smooth rotation is actually coded into Sonic 1 and not used. I think I can see why - it's hard to see in the video because the jerk playing it keeps jumping, but you can kind of see tiles slip slightly out of place as it rotates, making flat walls look not perfectly flat and such. It makes sense that they'd limit it to only increments that look perfect, but I'm still disappointed that they did it because it just looks SO GOOD rotating smoothly...

Seems like that's how you'd do rotating objects though, I can't think of a better way.

[Drew Sebastino]

You all realize that that's the iOS version, right? (I'm sure you guys already know you can't be Knuckles in Sonic 1, even with the Sonic and Knuckles cartridge.) The code isn't even based on Sonic 1's, it's based on Sonic CD's, so the bonus stage code was built from scratch.

[Khaz]

Oh.

Uh.

Is there video of actual Sonic 1 with the actual rotation hack?

[Drew Sebastino]

Oh.Uh.

Not very impressive anymore.

Oh.

Uh.

Is there video of actual Sonic 1 with the actual rotation hack?

It's only been made for iOS. The code apparently did something to where it inhibited the rotation from progressing for about 1 second and then it allowed it to jump to that position and then do the same thing. The person just got rid of that little bit of code so that it rotated smoothly. As for the original Sonic 1 doing the the same thing, I don't think anyone has even attempted it. It is definitely different from the iOS version when it comes to the code, so it wouldn't be as easy to make the hack because you'd have to code it from scratch. It's certainly feasible, it would just take a lot more animation.

[Khaz]

Ah. So there was never any smooth rotation in actual Sonic 1. I see...