Data manipulation algorithm

Hello everybody. I'm currently developing a space exploration game project and I need some help.

Here is the situation :

I have a 3D cubic universe that is divided into cells. Each cell have a fixed size. Two cells are not necessarly side by side ( in a two cells universe, you can have one at (0,0,0) and another at (20,20,13)). The universe don't have a fixed size. The cells can have negative coordinates.


Roughly, I need a way to manage the cells in memory and on the disk. On the disk, it's not too bad, i can store them in a file easily.
But I need a fast way to manipulate the cells in memory. I've thought about a tridimensional array, but my universe can be almost empty, so the ressource cost will be useless. I've thought about octrees, but the whole system is too much complex and I think that there is another possibility. So I thought about a hash table with the coordinates of the cell for key.


here is what I'm asking :

If anybody can explain me the way a hash table can be implemented manually, or if someone have some documentation about it, please, drop me a line. I've used hash tables in Perl and in PHP, but I'm programming in Delphi and it's not built-in


Thanks a lot in advance,

Blaise Bernier

URL

http://homepages.borland.com/efg2la...rithms/#Hashing

Hope this helps

Thanks a lot, I'll take a look at it