[quote name='Eelco' timestamp='1308647979' post='4825892']
But after the minecraft terrain is generated, its freely manipulable, as a frigging volume. All terrain that has even been manipulated (which tends to happen a lot in minecraft) also needs to be stored in memory from that point on. Actually I think youd even need to store all terain that has ever been seen, considering there is a lot of dynamic stuff like tree growth and monster spawning going on, even when these areas are nothing even remotely resembling being in view.
I myself am pretty amazed at how well minecraft handles this. These worlds are not just infinite in theory; there are videos in which people actually build insanely long roads for instance, without showing any signs of slowing down. I havnt seen its equal yet
Store the Seed Data for a chunk, then a 'mask' that contains the difference between the seed and what the current state of the chunk/subchuck is.
When you then go back to the area the computer takes the seed value and regenerates the land 100% the same as it was the first time, then applies the masks to make up for the changes. Most chunks will have next to no mask data, some chunks will have more. Additionally you can apply some basic compression methods to your masks to reduce the data needed to actually store the mask.
How you implement the mask would then depend on how the world is generated and what you expect to be done with it.
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Thats all rather obvious, but the bottom line is that i have not see anyone do anything of similar complexity.
