tepples wrote:
An octahedron is isotopic to a sphere. By ripping four edges adjacent to one vertex, it becomes isotopic to a square interior. You go off (say) edge b, and you come out at edge b', from which it was ripped.
Specifically just mapping a square to a sphere isn't a big problem. There are all sorts of ways to do that; the cylindrical projection is probably the most popular method. The problem is dealing with a grid that you're not really able to distort, and might be impractical to change the orientation too.
Rendering this octahedron scheme as a 2D JRPG map would involve having the world appear in 4 different rotations depending on where/when you cross those edges. Around the midpoints of those edges things would get really confusing, like you'd be able to see a place diagonally across from its 180-degree twin on the same screen. I don't think it'd be very intuitive for the player, even if it technically could map to a "spherical" world. The distortion and loss of orientation here is a problem.
From a rendering standpoint, it'd be usable for Sonic 3's bonus stages, maybe, since it's a rotating perspective anyway? However, I think for level design it'd probably be a real pain to deal with the way it wraps, not to mention confusing for the player trying to figure out why in some places they can turn left 2 times and end up where they started.
I've seen a cylinder world in games a few times. Civilization IV, for example, blocks the north and south pole with a wall of ice, and otherwise lets it wrap horizontally. Keeps the nice flat grid, as well as the idea of a circumnavigable earth, but in addition to losing the ability to travel across the poles, the north and south extremes are also far too wide, the spherical shape it not being represented. Always therer is this conflict between keeping an oriented grid and not distorting its shape vs. the sphere.
psycopathicteen wrote:
Is Super Mario Galaxy the only game that has Topography that makes sense?
The earliest game I can remember playing that had an actual no-compromises spherical world map was
X-Com: UFO Defense (1994). There's probably earlier examples, though.