i understand that there's a new chunked terrain feature in 6.4 but there doesn't seem to be any example or tutorial on how to use this. can anyone point me to some resources concerning this?
You not need a tutorial for this, the chunk system is in the engine self, The engine divide the terrain in a small piece. You create a terrain for example 1024 x 1024, then the engine will andle this terrain not like an only piece but like if it would be many small quadrates for example each piece of 256 pixel 16 piece of each 256 pixel.
THe example is in the update manual, basically its on by default and can be disabled by changing chunk size to "0", example "var terrain_chunk = 0;" or if left on meaning chunk size is set to a value from "1" to "256" can be told to ignore specific terrain files by changing the file name of the terrain to end with "_" or "_n", example "terrainR1C3_n.hmp". There are consiquences like mesh deformation is disabled when chunked.
