From a programming perspective, it provided for some rough challenges, yes
We spent the better part of nine or ten months just working on the spherical world (how to represent it in memory, how to display it, how to allow the player to manipulate the maps, etc.). I tried various methods for tiling a sphere, and getting it to display properly, and (most difficultly) getting it to scroll without visible distortions showing up on the playfield.
We finally ended up using Direct3D to display the sphere, which is nothing more than a ball shaped skeleton, and then pasted the terrain texture over the top of it. The tricky bit with the terrain texture is that textures need to be represented in memory as rectangular. But, as you know, you can't wrap a sphere with a rectangle without distorting it. It turns out that when you do such a wrap, you get the exact opposite distortions that a mercator projection causes. Those bits near the top and bottom of the rectangle shrink horizontally when applied to the sphere. Our first attempts at this wrap didn't look very good, because it appeared that land masses compressed as they moved south to north, or north to south. The solution, which took some time to program, was to deliberately distort the rectangular texture picture so that the land masses expanded horizontally as they moved toward a pole (just like a mercator projection does). Then, when wrapped back onto a sphere, they would distort back to the original shape, and look alright on the globe.
Another thing that causes me lots of headaches is path finding. Of course, the textures representations are rectangular, and it is natural to look at them when trying to find the best path. The problem is that when you draw a straight line on a rectangular texture (from point A to point B), and then translate that to a sphere, it curves. Player stacks will spiral toward the poles rather than move straight to them. In order to get a straight line on the sphere, you have to first translate the coordinates of your points into a polar coordinate system and examine all your terrains from there. We
still have problems with that phenomonon, though they are not as bad as they used to be.
The game would have been a lot easier to work with and have been done a lot sooner if we had stuck with a regular flat map, and I can certainly understand why game designers don't want to mess with spherical ones. But I decided we had to have a spherical world, and I can be stubborn once I've decided something is needed
Ron
