I know normally the server does not send data about "other" worlds to a client. However, I find myself in need of this and with no way around it that I can forsee. DimensionManager only works serverside (it returns null clientside), so that is not a solution.

 

Basically, I need the ability, clientside, to have the ability to do something like world.getBlock() where world is, say, the Nether while the client player is in the overworld.

 

Perhaps Packet#MapChunk is involved, but I have no idea how to use it for this.

 

 

No, rewriting the system to just send the checks to the server and back is not possible because of how complex and dynamic it is, as well as the fact that "delayed response" is not acceptable for my application.

It can be done. Look at XCompWiz's Looking Glass mod.

The only way I can think to do it is passing packets back and forth for that block.  This would be just as fast or faster than vanilla depending what you are wanting to do.

 

Are you wanting to destroy it or find out something about it?