Procedural Planets, Heightmaps and textures

Question

I am currently working on an OpenGL procedural planet generator. I hope to use it for a space RPG, that will not allow players to go down to the surface of a planet so I have ignored anything ROAM related. At the momement I am drawing a cube with VBOs and mapping onto a sphere as shown here.

I am familiar with most fractal heightmap generating techniques and have already implemented my own version of midpoint displacement(not that useful in this case I know).

My question is, what is the best way to procedurally generate the heightmap. I have looked at libnoise which allows me to make tilable heightmaps/textures, but as far as I can see I would need to generate a net like:

Leaving the tiling obvious.

Could anyone advise me on the best route to take?

Any input would be much appreciated.

Thanks,

Henry.

Answer 1

It looks like you understand the problem with generating a flat, seamless surface and then trying to map it onto a sphere.

How about using a 3D noise function instead? A 3D noise function takes 3 coordinates instead of 2 as its input, so imagine a 3D array full of generated numbers (instead of a 2D array). Thus, once you have a 3D noise function, you can generate a 2D texture, but instead of using 2D coordinates for each pixel, use the 3D coordinates of where that pixel would be on the sphere. (I hope that convoluted sentence made sense!)

Take a look at halfway-down this page about Perlin noise: https://web.archive.org/web/20120829114554/http://local.wasp.uwa.edu.au/~pbourke/texture_colour/perlin/

I think it describes exactly what you want with regards to spheres.

Answer 2

You may also want to check out this article from 2004 on how to 'split' up a sphere into manageable parts.

http://www.gamedev.net/reference/articles/article2074.asp