Restrict placement of small mushrooms to dark, opaque, solid blocks

mods/ITEMS/mcl_mushrooms/small.lua

@@ -1,3 +1,47 @@
+local on_place = function(itemstack, placer, pointed_thing)
+	if pointed_thing.type ~= "node" then
+		-- no interaction possible with entities
+		return itemstack
+	end
+
+	-- Call on_rightclick if the pointed node defines it
+	local node = minetest.get_node(pointed_thing.under)
+	if placer and not placer:get_player_control().sneak then
+		if minetest.registered_nodes[node.name] and minetest.registered_nodes[node.name].on_rightclick then
+			return minetest.registered_nodes[node.name].on_rightclick(pointed_thing.under, node, placer, itemstack) or itemstack
+		end
+	end
+
+	local a = pointed_thing.above
+	local node_above = minetest.get_node(a)
+	local node_below = minetest.get_node({x=a.x, y=a.y-1, z=a.z})
+	local def = minetest.registered_nodes[node_below.name]
+	local def2 = minetest.registered_nodes[node_above.name]
+
+	-- Placement rules:
+	-- * Always allowed on podzol or mycelimu
+	-- * Otherwise, must be solid, opaque and have daylight light level <= 12
+	local light = minetest.get_node_light(a, 0.5)
+	local light_ok = false
+	if light and light <= 12 then
+		light_ok = true
+	end
+	if (node_below.name == "mcl_core:podzol" or node_below.name == "mcl_core:mycelium") or
+			(light_ok and (def.groups and def.groups.solid and def.groups.opaque)) and
+			def2.buildable_to then
+		local idef = itemstack:get_definition()
+		local success = minetest.item_place_node(itemstack, placer, pointed_thing)
+
+		if success then
+			if idef.sounds and idef.sounds.place then
+				minetest.sound_play(idef.sounds.place, {pos=above, gain=1})
+			end
+		end
+	end
+
+	return itemstack
+end
+
 minetest.register_node("mcl_mushrooms:mushroom_brown", {
 	description = "Brown Mushroom",
 	drawtype = "plantlike",
@@ -14,6 +58,8 @@ minetest.register_node("mcl_mushrooms:mushroom_brown", {
 		type = "fixed",
 		fixed = { -0.15, -0.5, -0.15, 0.15, 0.015, 0.15 },
 	},
+	node_placement_prediction = "",
+	on_place = on_place,
 	_mcl_blast_resistance = 0,
 })
 
@@ -32,6 +78,8 @@ minetest.register_node("mcl_mushrooms:mushroom_red", {
 		type = "fixed",
 		fixed = { -0.15, -0.5, -0.15, 0.15, 0.015, 0.15 },
 	},
+	node_placement_prediction = "",
+	on_place = on_place,
 	_mcl_blast_resistance = 0,
 })