RTS on a 3D map e.g. a globe

Question

How can you 'tile' a 3D globe if your existing artwork and maps are simple 2D grids?

Are there approaches that can re-use much of the artwork and such?

Answer 1

I've built something like what you're looking for. I used this site mostly as a reference for the map build process. BUGS Geodesic Map

The basic steps:

• Create an icosahedron. Each 'cell' will be one of the vertices on the mesh. Subdivide to desired resolution.
• Treat each icosahedron vertex as the cell center - the geogrid's cell vertices are the midpoints of each icosahedron triangle face.
• Using the indices of the icosahedron mesh, you can lookup cell neighbors and built up their correct order - this will let you build the cell faces correctly.
• You will have 12 pentagons and the rest will be hexagons - there's no way around this.
• Some people I've seen like to try and convert down to a 2d grid (examples of the process on the BUGS site), and it's possible. I never did this because it's hard and can be worked around.

In mine, the whole grid is one giant mesh, not repeated cell models (http://blog.chronoclast.com/search/label/OTD). For lower mesh resolutions this runs okay. If you're looking at tens of thousands of cells, you'll want to explore more dynamic mesh building - mine is all pre-built. Cells are textured off a page-map (2/9/16... textures per image) and can blend uv's (that was hard, took forever, still kind of meh).

Answer 2

Our game "Save Us!" used that. It is pretty fun to have rts on planet and control it. Save us gameplay (but the game is not fun at all :-))

Save Us! Uses regular 2D heightmap which is transformed to a sphere. It is easy to do, but has problem on sphere's poles. We just have there ocean. Not really nice solution, but works. Problem of non rectangular tiles is not big. It looks quite ok. For determining which tile is clicked we use color picking.

This is old project and the solution is not the best, but it is very very easy and quite good looking.

Much better solution should be usage of icosphere.

Answer 3

Here are a couple of articles from Spore

Creating Spherical Worlds

• Abstract
• Slides
• And YouTube Clip