modlib/minetest/boxes.lua

-- Localize globals
local assert, ipairs, math, minetest, table, type, vector
	= assert, ipairs, math, minetest, table, type, vector

-- Set environment
local _ENV = ...
setfenv(1, _ENV)

-- Minetest allows shorthand box = {...} instead of {{...}}
local function get_boxes(box_or_boxes)
	return type(box_or_boxes[1]) == "number" and {box_or_boxes} or box_or_boxes
end

local has_boxes_prop = {collision_box = "walkable", selection_box = "pointable"}

-- Required for raycast box IDs to be accurate
local connect_sides_order = {"top", "bottom", "front", "left", "back", "right"}

local connect_sides_directions = {
	top = vector.new(0, 1, 0),
	bottom = vector.new(0, -1, 0),
	front = vector.new(0, 0, -1),
	left = vector.new(-1, 0, 0),
	back = vector.new(0, 0, 1),
	right = vector.new(1, 0, 0),
}

--> list of collisionboxes in Minetest format
local function get_node_boxes(pos, type)
	local node = minetest.get_node(pos)
	local node_def = minetest.registered_nodes[node.name]
	if not node_def or node_def[has_boxes_prop[type]] == false then
		return {}
	end
	local boxes = {{-0.5, -0.5, -0.5, 0.5, 0.5, 0.5}}
	local def_node_box = node_def.drawtype == "nodebox" and node_def.node_box
	local def_box = node_def[type] or def_node_box -- will evaluate to def_node_box for type = nil
	if not def_box then
		return boxes -- default to regular box
	end
	local box_type = def_box.type
	if box_type == "regular" then
		return boxes
	end
	local fixed = def_box.fixed
	boxes = get_boxes(fixed or {})
	local paramtype2 = node_def.paramtype2
	if box_type == "leveled" then
		boxes = table.copy(boxes)
		local level = (paramtype2 == "leveled" and node.param2 or node_def.leveled or 0) / 255 - 0.5
		for _, box in ipairs(boxes) do
			box[5] = level
		end
	elseif box_type == "wallmounted" then
		local dir = minetest.wallmounted_to_dir((paramtype2 == "colorwallmounted" and node.param2 % 8 or node.param2) or 0)
		local box
		-- The (undocumented!) node box defaults below are taken from `NodeBox::reset`
		if dir.y > 0 then
			box = def_box.wall_top or {-0.5, 0.5 - 1/16, -0.5, 0.5, 0.5, 0.5}
		elseif dir.y < 0 then
			box = def_box.wall_bottom or {-0.5, -0.5, -0.5, 0.5, -0.5 + 1/16, 0.5}
		else
			box = def_box.wall_side or {-0.5, -0.5, -0.5, -0.5 + 1/16, 0.5, 0.5}
			if dir.z > 0 then
				box = {box[3], box[2], -box[4], box[6], box[5], -box[1]}
			elseif dir.z < 0 then
				box = {-box[6], box[2], box[1], -box[3], box[5], box[4]}
			elseif dir.x > 0 then
				box = {-box[4], box[2], box[3], -box[1], box[5], box[6]}
			else
				box = {box[1], box[2], -box[6], box[4], box[5], -box[3]}
			end
		end
		return {assert(box, "incomplete wallmounted collisionbox definition of " .. node.name)}
	end
	if box_type == "connected" then
		boxes = table.copy(boxes)
		local connect_sides = connect_sides_directions -- (ab)use directions as a "set" of sides
		if node_def.connect_sides then -- build set of sides from given list
			connect_sides = {}
			for _, side in ipairs(node_def.connect_sides) do
				connect_sides[side] = true
			end
		end
		local function add_collisionbox(key)
			for _, box in ipairs(get_boxes(def_box[key] or {})) do
				table.insert(boxes, box)
			end
		end
		local matchers = {}
		for i, nodename_or_group in ipairs(node_def.connects_to or {}) do
			matchers[i] = nodename_matcher(nodename_or_group)
		end
		local function connects_to(nodename)
			for _, matcher in ipairs(matchers) do
				if matcher(nodename) then
					return true
				end
			end
		end
		local connected, connected_sides
		for _, side in ipairs(connect_sides_order) do
			if connect_sides[side] then
				local direction = connect_sides_directions[side]
				local neighbor = minetest.get_node(vector.add(pos, direction))
				local connects = connects_to(neighbor.name)
				connected = connected or connects
				connected_sides = connected_sides or (side ~= "top" and side ~= "bottom")
				add_collisionbox((connects and "connect_" or "disconnected_") .. side)
			end
		end
		if not connected then
			add_collisionbox("disconnected")
		end
		if not connected_sides then
			add_collisionbox("disconnected_sides")
		end
		return boxes
	end
	if box_type == "fixed" and paramtype2 == "facedir" or paramtype2 == "colorfacedir" then
		local param2 = paramtype2 == "colorfacedir" and node.param2 % 32 or node.param2 or 0
		if param2 ~= 0 then
			boxes = table.copy(boxes)
			local axis = ({5, 6, 3, 4, 1, 2})[math.floor(param2 / 4) + 1]
			local other_axis_1, other_axis_2 = (axis % 3) + 1, ((axis + 1) % 3) + 1
			local rotation = (param2 % 4) / 2 * math.pi
			local flip = axis > 3
			if flip then axis = axis - 3; rotation = -rotation end
			local sin, cos = math.sin(rotation), math.cos(rotation)
			if axis == 2 then
				sin = -sin
			end
			for _, box in ipairs(boxes) do
				for off = 0, 3, 3 do
					local axis_1, axis_2 = other_axis_1 + off, other_axis_2 + off
					local value_1, value_2 = box[axis_1], box[axis_2]
					box[axis_1] = value_1 * cos - value_2 * sin
					box[axis_2] = value_1 * sin + value_2 * cos
				end
				if not flip then
					box[axis], box[axis + 3] = -box[axis + 3], -box[axis]
				end
				local function fix(coord)
					if box[coord] > box[coord + 3] then
						box[coord], box[coord + 3] = box[coord + 3], box[coord]
					end
				end
				fix(other_axis_1)
				fix(other_axis_2)
			end
		end
	end
	return boxes
end

function _ENV.get_node_boxes(pos)
	return get_node_boxes(pos, nil)
end

function get_node_selectionboxes(pos)
	return get_node_boxes(pos, "selection_box")
end

function get_node_collisionboxes(pos)
	return get_node_boxes(pos, "collision_box")
end