Biomes 0.4.13
Mgv6
Mgv6 now has snow biomes (taiga and tundra) enabled by default when you start a new world. Jungles are larger, and biomes are moved around to their correct locations determined by mgv6 'biome' (heat) and 'humidity' noises. The classic biome system locates biomes in a way that does not make complete sense if 'biome' noise is considered to be heat.
To disable this new 5-biome system and use the classic biome system add ..
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.. to minetest.conf when you start a new world.
Existing worlds that use the classic biome system will continue to use it because the 'mg_flags' for the world does not contain the 'snowbiomes' flag.
The new 5-biome system first uses 'biome' (heat) noise to divide the world into cold, temperate and hot areas.
Then, 'humidity' noise divides hot areas into desert and jungle, and divides cold areas into tundra (dry) and taiga.
Arranged vertically from cold to hot, and horizontally from dry to wet:
Desert ... Jungle
'Normal' (randomly divided into grassland and deciduous forest)
Tundra ... Taiga
Mgv5
Mgv7
Fractal (future mapgen)
For 0.4.13 a full biome system has been added using the biome API. The biome system is independant of the base terrain mapgen chosen and will be usable with future mapgens also, it cannot be used with mgv6 which has it's own hardcoded biome systems.
'Heat' and 'humidity' noises are used to locate 10 biomes, a new biome blend method is used that has it's own noises ('heat blend' and 'humidity blend') so can be customised or disabled by editing the noise parameters.
Arranged vertically from cold to hot, and horizontally from dry to wet:
Desert ... Savanna ... Rainforest
Sandstone grassland .. Deciduous forest
Stone grassland ... Coniferous forest
Tundra ... Taiga
Glacier
Sandstone and desert stone contain no ores and extend down to y = -112, below this there is the 'underground' biome which uses 'default:stone' throughout the world.