turn underwater pillars/stalagmites in the Sunless Sea into cave coral

df_caverns/sunless_sea.lua

@@ -9,6 +9,12 @@ local c_dry_flowstone = minetest.get_content_id("df_mapitems:dry_flowstone")
 local c_lava = minetest.get_content_id("default:lava_source")
 local c_obsidian = minetest.get_content_id("default:obsidian")
 
+local c_coral_table = {
+	minetest.get_content_id("df_mapitems:cave_coral_1"),
+	minetest.get_content_id("df_mapitems:cave_coral_2"),
+	minetest.get_content_id("df_mapitems:cave_coral_3")
+}
+
 local mushroom_shrublist
 local fungispore_shrublist
 
@@ -357,15 +363,19 @@ local decorate_sunless_sea = function(minp, maxp, seed, vm, node_arrays, area, d
 
 	-- columns
 	for _, vi in ipairs(node_arrays.column_nodes) do
-		local index2d = mapgen_helper.index2di(minp, maxp, area, vi)
-		local heat = heatmap[index2d]
-
-		if area:get_y(vi) > sea_level and heat > hot_zone_boundary and data[vi] == c_wet_flowstone then
-			data[vi] = c_dry_flowstone
+		if data[vi] == c_wet_flowstone then
+			if area:get_y(vi) > sea_level then
+				local index2d = mapgen_helper.index2di(minp, maxp, area, vi)
+				local heat = heatmap[index2d]
+				if heat > hot_zone_boundary then
+					data[vi] = c_dry_flowstone
+				end
+			else
+				data[vi] = c_coral_table[math.random(1,3)]
+			end
 		end
 	end
 
-	
 	vm:set_param2_data(data_param2)
 end
 

df_caverns/underworld.lua

@@ -209,7 +209,7 @@ local get_pit = function(pos)
 	if region_mapblocks < 1 then return nil end
 
 	local corner_xz = get_corner(pos)
-	local next_seed = math.random(1, 2^31)
+	local next_seed = math.floor(math.random() * 2^31)
 	math.randomseed(corner_xz.x + corner_xz.z * 2 ^ 8 + mapgen_seed)
 	local location = scatter_2d(corner_xz, pit_region_size, radius_pit_max + radius_pit_variance)
 	local variance_multiplier = math.random()

df_mapitems/cave_coral.lua

@@ -42,6 +42,7 @@ local coral_names = {"df_mapitems:cave_coral_1", "df_mapitems:cave_coral_2", "df
 minetest.register_abm{
 	label = "df_mapitems:shifting_coral",
 	nodenames = {"group:dfcaverns_cave_coral"},
+	neighbors = {"default:water_source"},
 	interval = 2,
 	chance = 10,
 	action = function(pos)

df_trees/blood_thorn.lua

@@ -173,7 +173,7 @@ minetest.register_craft({
 
 -- This ensures consistent random maximum to bloodthorn growth
 local max_bloodthorn_height = function(pos)
-	local next_seed = math.random(1, 2^31)
+	local next_seed = math.floor(math.random() * 2^31)
 	math.randomseed(pos.x + pos.z * 2 ^ 8)
 	local output = math.random(3,6)
 	math.randomseed(next_seed)