Mapgen objects

A mapgen object is a construct used in map generation. Mapgen objects can be used by an on_generate callback to speed up operations by avoiding unnecessary recalculations, these can be retrieved using the minetest.get_mapgen_object() function. If the requested Mapgen object is unavailable, or get_mapgen_object() was called outside of an on_generate() callback, nil is returned.

The following Mapgen objects are currently available:

voxelmanip

This returns three values; the VoxelManip object to be used, minimum and maximum emerged position, in that order. All mapgens support this object.

heightmap

Returns an array containing the y coordinates of the ground levels of nodes in the most recently generated chunk by the current mapgen.

biomemap

Returns an array containing the biome IDs of nodes in the most recently generated chunk by the current mapgen.

heatmap

Returns an array containing the temperature values of nodes in the most recently generated chunk by the current mapgen.

humiditymap

Returns an array containing the humidity values of nodes in the most recently generated chunk by the current mapgen.

gennotify

Returns a table mapping requested generation notification types to arrays of positions at which the corresponding generated structures are located within the current chunk. To set the capture of positions of interest to be recorded on generate, use minetest.set_gen_notify(). For decorations, the returned positions are the ground surface 'place_on' nodes, not the decorations themselves. A 'simple' type decoration is often 1 node above the returned position and possibly displaced by 'place_offset_y'.

Possible fields of the table returned are:

  • dungeon
  • temple
  • cave_begin
  • cave_end
  • large_cave_begin
  • large_cave_end
  • decoration

Decorations have a key in the format of "decoration#id", where id is the numeric unique decoration ID as returned by minetest.get_decoration_id.