nesdev.org

How feasible is it to make a program for the NES that lets the user explore the surface of a sphere? Such as a replica of planet Earth?

I doubt it would be possible for the NES to handle a nice RPG overworld in the shape of a spheroid. But maybe it could do something simpler?

A mapper that allows megabytes of CHR, all frames of the sphere are prerendered.

Real time sphere mapping on the NES with good resolution is not doable.

I think you need to be more specific about what you want to see. A lot of things are possible.

e.g. 3-D Worldrunner: http://www.youtube.com/watch?v=odvamQHZy2w (UNROM by the way, no scanline counter needed)

The impression of exploring a curved surface could be difficult, but I'm not going to call it impossible. There is plenty of room to come up with some novel solution (break down your problem until you find something that will work).

However, since you're asking at this point, it sounds like you're not particularly familiar with what the NES can do. If this is the case, I'm not sure how you will expect to implement an advanced rendering technique for it even if we did tell you how to solve the problem.

Anyhow, what is it you want, visually? Can you draw a picture?

You want something that looks like the Blue Spheres minigame from Sonic 3? That's doable, use static frames of animation for the rotation, as well as 3D WorldRunner style scroll effects.

You want to do 3D transformations to make small scenery sprites be placed correctly as a camera angle and location changes?
I bet it could be pulled off with a small number of objects. Might not be 60FPS though.
Probably easier to do it on a plane than a sphere.

Most modern games run at 30fps or lower and few people seem to care. I appreciate the smoothness of 60, but if you need to drag your solution out over two frames to accomplish something interesting, sure, go for it.

Shiru wrote: Real time sphere mapping on the NES with good resolution is not doable.

Press B+Select on the world map in Final Fantasy II after you got the "Ring" item (which is the first mission).

Bregalad wrote:Press B+Select on the world map in Final Fantasy II after you got the "Ring" item (which is the first mission).

Care to explain/show what this does for people like me who don't like/know how to play NES RPGs?

tokumaru wrote:

Bregalad wrote:Press B+Select on the world map in Final Fantasy II after you got the "Ring" item (which is the first mission).

Care to explain/show what this does for people like me who don't like/know how to play NES RPGs?

BINGO.

But Final Fantasy II's overworld isn't a spheroid and the map doesn't function in real time.

Edit: It doesn't matter if it looks like you are on a curved surface. Just that it is an actual globe, rather than a torus. An imprecise way of rendering it might be fine.

An "overworld" that is on the surface of a globe gets weird because it won't neatly wrap from one edge to the opposite edge like the square overworlds that we are used to, which only could be mapped to a torus in 3D.

Judging from maps that somebody made, it seems that Sonic 3's blue sphere game is played out on a square, that uses an illusion to make it look like a curved surface. I have no idea if the same applies to 3D World Runner or not. My guesss would be that it is a square too..

Final Fantasy II map:
http://www.youtube.com/watch?v=Vdlu-UznVjc#t=5m48s

Oh so you're not asking about a graphical effect, you're interested in a world map that is topologically a sphere?

Representing a spherical map with a planar grid is as doable on an NES as anywhere else, which is to say it's always a bit wonky.

rainwarrior wrote:Oh so you're not asking about a graphical effect, you're interested in a world map that is topologically a sphere?

Yes.

Not very common in games that aren't using a full 3D representation of the sphere (I don't know of any). Even Civilization IV just made the poles impassible and treated it as a cylinder.

You could maybe split scanlines between tiles, so that as you traverse left and right, rows closer to the poles scroll slower than the row you're on, closer to the equator scrolls faster (store the world as rows of variable length). Visually stuff at the sides of the screen will look misaligned, though, but maybe you'd be willing to live with this for the sake of a spherical map.

You could maybe do it like a King's Quest game, where you get static pages, and just link them like a sphere would be linked. You'll have points, like at the poles, where going "west" should link to the "north" side of the screen below, etc. but that kind of thing is unavoidable.

You could probably even do some low resolution 3D rendering on the NES, maybe a bit slowly though, and there'd be a ton of rough aliasing. It would be difficult to do collision reliably.

If your world can be a boring plain sphere with all points of interesting being sprites, you could do it okay, since this should permit rotation (of the sprite positions, not the actual sprites) without too much problem. e.g. something like worldrunner could traverse a sphere (excepting the checkerboard ground).

Bregalad wrote:Press B+Select on the world map in Final Fantasy II after you got the "Ring" item (which is the first mission).

By 'real time sphere mapping' I mean an effect like this (also used as 'magnifying glass' in other demos), not a boring static picture that is certainly not 'real time'

Maybe it would have to be like 3-D WorldRunner or Cosmic Epsilon... and rely on sprites.

I thought of the way that is apparently used in King's Quest as you have described it, rainwarrior. It's cool to hear of a game that actually has a spherical world, unless I am misunderstanding.

The split scanlines thing sounds pretty exotic, it would be a cool thing to show off.

I think fluid motion would probably be a higher priority than accuracy, maybe, if there has to be that kind of tradeoff. The aim is to have something somewhat immersive.