Cavegen/Mgv5/Mgv7: Add optional giant caverns

Add to MapgenBasic for use by multiple mapgens.
Add to mgv5 and mgv7, enabled by default.

Similar to mgvalleys caverns but half the scale.
Parameters for upper y limit, distance caverns taper to full size, and
noise threshold (full cavern size).
As with mgvalleys caverns are generated first and classic caves are
disabled in any mapchunk containing a cavern, to avoid excessive
spreading volumes of liquids.
This also avoids floating blobs of liquid where a large classic cave
has overgenerated out into a neighbouring previously-generated mapchunk.

1 files changed, 23 insertions, 0 deletions

diff --git a/builtin/settingtypes.txt b/builtin/settingtypes.txt
index c9e0f7b87..bbee77749 100644
--- a/builtin/settingtypes.txt
+++ b/builtin/settingtypes.txt
@@ -940,12 +940,25 @@ mg_biome_np_humidity_blend (Mapgen biome humidity blend noise parameters) noise_
 #    Controls width of tunnels, a smaller value creates wider tunnels.
 mgv5_cave_width (Mapgen v5 cave width) float 0.125
 
+#    Y-level of cavern upper limit.
+mgv5_cavern_limit (Mapgen v5 cavern limit) int -256
+
+#    Y-distance over which caverns expand to full size.
+mgv5_cavern_taper (Mapgen v5 cavern taper) int 256
+
+#    Defines full size of caverns, smaller values create larger caverns.
+mgv5_cavern_threshold (Mapgen v5 cavern threshold) float 0.7
+
 mgv5_np_filler_depth (Mapgen v5 filler depth noise parameters) noise_params 0, 1, (150, 150, 150), 261, 4, 0.7, 2.0
 mgv5_np_factor (Mapgen v5 factor noise parameters) noise_params 0, 1, (250, 250, 250), 920381, 3, 0.45, 2.0
 mgv5_np_height (Mapgen v5 height noise parameters) noise_params 0, 10, (250, 250, 250), 84174, 4, 0.5, 2.0
 mgv5_np_cave1 (Mapgen v5 cave1 noise parameters) noise_params 0, 12, (50, 50, 50), 52534, 4, 0.5, 2.0
 mgv5_np_cave2 (Mapgen v5 cave2 noise parameters) noise_params 0, 12, (50, 50, 50), 10325, 4, 0.5, 2.0
+mgv5_np_cavern (Mapgen v5 cavern noise parameters) noise_params 0, 1, (384, 128, 384), 723, 5, 0.63, 2.0
 #    TODO
+#    Noise parameters in group format, unsupported by advanced settings
+#    menu but settable in minetest.conf.
+#    See documentation of noise parameter formats in minetest.conf.example.
 #mgv5_np_ground = {
 #    offset      = 0
 #    scale       = 40
@@ -1007,6 +1020,15 @@ mgv7_floatland_level (Mapgen v7 floatland level) int 1280
 #    Y-level to which floatland shadows extend.
 mgv7_shadow_limit (Mapgen v7 shadow limit) int 1024
 
+#    Y-level of cavern upper limit.
+mgv7_cavern_limit (Mapgen v7 cavern limit) int -256
+
+#    Y-distance over which caverns expand to full size.
+mgv7_cavern_taper (Mapgen v7 cavern taper) int 256
+
+#    Defines full size of caverns, smaller values create larger caverns.
+mgv7_cavern_threshold (Mapgen v7 cavern threshold) float 0.7
+
 mgv7_np_terrain_base (Mapgen v7 terrain base noise parameters) noise_params 4, 70, (600, 600, 600), 82341, 5, 0.6, 2.0
 mgv7_np_terrain_alt (Mapgen v7 terrain altitude noise parameters) noise_params 4, 25, (600, 600, 600), 5934, 5, 0.6, 2.0
 mgv7_np_terrain_persist (Mapgen v7 terrain persistation noise parameters) noise_params 0.6, 0.1, (2000, 2000, 2000), 539, 3, 0.6, 2.0
@@ -1018,6 +1040,7 @@ mgv7_np_floatland_base (Mapgen v7 floatland base terrain noise parameters) noise
 mgv7_np_float_base_height (Mapgen v7 floatland base terrain height noise parameters) noise_params 48, 24, (300, 300, 300), 907, 4, 0.7, 2.0
 mgv7_np_mountain (Mapgen v7 mountain noise parameters) noise_params -0.6, 1, (250, 350, 250), 5333, 5, 0.63, 2.0
 mgv7_np_ridge (Mapgen v7 river channel wall noise parameters) noise_params 0, 1, (100, 100, 100), 6467, 4, 0.75, 2.0
+mgv7_np_cavern (Mapgen v7 cavern noise parameters) noise_params 0, 1, (384, 128, 384), 723, 5, 0.63, 2.0
 mgv7_np_cave1 (Mapgen v7 cave1 noise parameters) noise_params 0, 12, (61, 61, 61), 52534, 3, 0.5, 2.0
 mgv7_np_cave2 (Mapgen v7 cave2 noise parameters) noise_params 0, 12, (67, 67, 67), 10325, 3, 0.5, 2.0