vm_lighting_wand/pointed_node.lua

local M = {}
local MT = minetest
local modname = MT.get_current_modname()

M.range = 8
M._ignored_node = {["air"] = true, ["ignore"] = true, ["unknown"] = true}
M._ignored_group = {[modname .. "_ignores"] = true}
M._ignored_drawtype = {["airlike"] = true}

M.check_groups = function(groups)
	if groups == nil then
		return true
	end
	for group, _ in pairs(groups) do
		if M._ignored_group[group] then
			return false
		end
	end
	return true
end

-- returns a noderef only if its still registered (uninstalled mod)
M.get_registered_node = function(pos)
	local node = MT.get_node_or_nil(pos)
	return MT.registered_nodes[node.name] ~= nil and MT.registered_nodes[node.name] or nil
end

-- given a player will return where ever the crosshair is pointing upto range limit
M.get_pointed_thing = function(player, objects, sneak)
	local result
	local eye_height = player:get_properties().eye_height or 1.625
	local eye_offset = player:get_eye_offset()
	local eye_pos = {
		x = eye_offset.x * 0.1,
		y = eye_height + eye_offset.y,
		z = eye_offset.z * 0.1
	}
	local pos = vector.add(player:get_pos(), eye_pos)
	local dir = player:get_look_dir()
	sneak = sneak and player:get_player_control().sneak or false
	objects = objects or false
	local ray = MT.raycast(pos, vector.add(pos, vector.multiply(dir, M.range)), objects, sneak)
	for pointed_thing in ray do
		local node_under = M.get_registered_node(pointed_thing.under)
		-- we found a node, check its not ignored
		if node_under ~= nil then
			if not M._ignored_drawtype[node_under.drawtype] and not M._ignored_node[node_under.name] then
				if M.check_groups(node_under.groups) then
					result = {
						pos_under = pointed_thing.under,
						pos_above = pointed_thing.above,
						node_under = node_under,
						node_above = M.get_registered_node(pointed_thing.above)
					}
					break
				end
			end
		else
			-- looks like we found a unknown node - uninstalled mod
			result = {
				pos_under = pointed_thing.under,
				pos_above = pointed_thing.above,
				node_under = nil,
				node_above = M.get_registered_node(pointed_thing.above)
			}
			break
		end
	end
	return result
end

return M