add option to have larger caverns stretch across cave layers

biomes.lua

@@ -79,6 +79,7 @@ subterrane:override_biome({
 
 subterrane:register_cave_decor(-113, dfcaverns.config.ymax)
 
+if dfcaverns.config.stone_between_layers then
 	subterrane:register_cave_layer({
 		minimum_depth = dfcaverns.config.ymax,
 		maximum_depth = dfcaverns.config.level1_min,
@@ -126,6 +127,23 @@ subterrane:register_cave_layer({
 			minimum_count = 10,
 		},
 	})
+else
+	subterrane:register_cave_layer({
+		minimum_depth = dfcaverns.config.ymax,
+		maximum_depth = dfcaverns.config.level3_min,
+		cave_threshold = dfcaverns.config.cavern_threshold,
+		perlin_cave = perlin_cave,
+		perlin_wave = perlin_wave,
+		columns = {
+			maximum_radius = 20,
+			minimum_radius = 4,
+			node = c_wet_flowstone,
+			weight = 0.25,
+			maximum_count = 50,
+			minimum_count = 0,
+		},
+	})
+end
 
 local perlin_cave_lava = {
 	offset = 0,
@@ -145,6 +163,7 @@ local perlin_wave_lava = {
 	persist = 0.63
 }
 
+--Sunless Sea
 subterrane:register_cave_layer({
 	minimum_depth = dfcaverns.config.level3_min,
 	maximum_depth = dfcaverns.config.sunless_sea_min,

config.lua

@@ -86,6 +86,7 @@ setting("float", "lava_sea_threshold", 0.2, "Cavern threshold for sunless and ma
 setting("bool", "enable_lava_sea", true, "Enable magma sea level")
 
 setting("bool", "flooded_biomes", true, "Add a lot of water to the most humid cavern biomes")
+setting("bool", "stone_between_layers", true, "Ensures that there's a solid stone floor/ceiling between cavern layers")
 
 if minetest.get_modpath("tnt") then
 	dfcaverns.config.enable_tnt = minetest.settings:get_bool("enable_tnt")

settingtypes.txt

@@ -44,6 +44,10 @@ dfcaverns_level3_min (Upper limit of the sunless sea) int -2100
 dfcaverns_sunless_sea_min (Lower limit of the sunless sea) int -2500
 dfcaverns_lava_sea_max (Upper limit of the lava sea) int -3000
 dfcaverns_lava_sea_min (Lower limit of the lava sea) int -3500
+#If this is true then there will never be a direct connection between caverns
+#of the first three cavern layers. If false, it's possible for caverns to
+#extend vertically through the boundary.
+dfcaverns_stone_between_layers (Ensure there's stone between layers) bool true
 
 [Lower Seas]
 #Determines threshold for lower sea cave generation. Higher number means sparser cavern