Decorations: Add kelp to cool and temperate shallow ocean

Original texture by tobyplowy, colourised by paramat.

mods/default/nodes.lua

@@ -149,6 +149,8 @@ default:acacia_bush_stem
 default:acacia_bush_leaves
 default:acacia_bush_sapling
 
+default:sand_with_kelp
+
 Corals
 ------
 
@@ -1449,6 +1451,55 @@ minetest.register_node("default:acacia_bush_sapling", {
 	end,
 })
 
+minetest.register_node("default:sand_with_kelp", {
+	description = "Kelp On Sand",
+	drawtype = "plantlike_rooted",
+	tiles = {"default_sand.png"},
+	special_tiles = {{name = "default_kelp.png", tileable_vertical = true}},
+	inventory_image = "default_kelp.png",
+	paramtype2 = "leveled",
+	groups = {snappy = 3},
+	node_placement_prediction = "",
+
+	on_place = function(itemstack, placer, pointed_thing)
+		-- Call on_rightclick if the pointed node defines it
+		if pointed_thing.type == "node" and placer and
+				not placer:get_player_control().sneak then
+			local node_ptu = minetest.get_node(pointed_thing.under)
+			local def_ptu = minetest.registered_nodes[node_ptu.name]
+			if def_ptu and def_ptu.on_rightclick then
+				return def_ptu.on_rightclick(pointed_thing.under, node_ptu, placer,
+					itemstack, pointed_thing)
+			end
+		end
+
+		local pos = pointed_thing.above
+		local height = math.random(4, 6)
+		local pos_top = {x = pos.x, y = pos.y + height, z = pos.z}
+		local node_top = minetest.get_node(pos_top)
+		local def_top = minetest.registered_nodes[node_top.name]
+		local player_name = placer:get_player_name()
+
+		if def_top and def_top.liquidtype == "source" and
+				minetest.get_item_group(node_top.name, "water") > 0 then
+			if not minetest.is_protected(pos, player_name) and
+					not minetest.is_protected(pos_top, player_name) then
+				minetest.set_node(pos, {name = "default:sand_with_kelp",
+					param2 = height * 16})
+				if not (creative and creative.is_enabled_for
+						and creative.is_enabled_for(player_name)) then
+					itemstack:take_item()
+				end
+			else
+				minetest.chat_send_player(player_name, "Node is protected")
+				minetest.record_protection_violation(pos, player_name)
+			end
+		end
+
+		return itemstack
+	end
+})
+
 
 --
 -- Corals