Move logic into rotate_node, separate files

init.lua

@@ -1,65 +1,20 @@
-local math, ipairs, tostring
-    = math, ipairs, tostring
-
 local minetest, vector, include
     = minetest, vector, include
 
-local function debug_tell(...)
-    local text = ""
-    for _, v in ipairs({...}) do text = text .. tostring(v) end
-    minetest.chat_send_all(text)
-end
-
-local AXIS_LOOKUP = {
-    vector.new( 0,  1,  0), -- +Y
-    vector.new( 0,  0,  1), -- +Z
-    vector.new( 0,  0, -1), -- -Z
-    vector.new( 1,  0,  0), -- +X
-    vector.new(-1,  0,  0), -- -X
-    vector.new( 0, -1,  0), -- -Y
-}
-
-local function unit_vector_to_axis_index(vec)
-    if     vec.y ==  1 then if vec.x == 0 and vec.z == 0 then return 1 end
-    elseif vec.z ==  1 then if vec.x == 0 and vec.y == 0 then return 2 end
-    elseif vec.z == -1 then if vec.x == 0 and vec.y == 0 then return 3 end
-    elseif vec.x ==  1 then if vec.y == 0 and vec.z == 0 then return 4 end
-    elseif vec.x == -1 then if vec.y == 0 and vec.z == 0 then return 5 end
-    elseif vec.y == -1 then if vec.x == 0 and vec.z == 0 then return 6 end
-    end
-    error("Not a unit vector")
-end
-
-local FACEDIR_LOOKUP = {}
-for up_index, up in ipairs(AXIS_LOOKUP) do
-    FACEDIR_LOOKUP[up_index] = {}
-    for rot = 0, 3 do
-        local facedir = (up_index - 1) * 4 + rot
-        local back = minetest.facedir_to_dir(facedir)
-        local back_index = unit_vector_to_axis_index(back)
-        FACEDIR_LOOKUP[up_index][back_index] = facedir
-    end
-end
+local rotate = include("rotate")
 
 minetest.register_on_punchnode(function(pos, node, puncher, pointed_thing)
     local def = minetest.registered_nodes[node.name]
-    if def.paramtype2 == "facedir" and pointed_thing.above and pointed_thing.under then
-        local facedir = node.param2
-        -- Vector that points away from the punched face.
-        local punched_face = vector.subtract(pointed_thing.above, pointed_thing.under)
-
-        local up   = AXIS_LOOKUP[1 + math.floor(facedir / 4)]
-        local back = minetest.facedir_to_dir(facedir)
+    if def.paramtype2 ~= "facedir" then return end
 
-        up   = up:rotate_around_axis(punched_face, math.rad(-90)):round()
-        back = back:rotate_around_axis(punched_face, math.rad(-90)):round()
+    -- Vector that points away from the punched face.
+    if (not pointed_thing.above) or (not pointed_thing.under) then return end
+    local axis = vector.subtract(pointed_thing.above, pointed_thing.under)
 
-        local up_index   = unit_vector_to_axis_index(up)
-        local back_index = unit_vector_to_axis_index(back)
+    -- Rotate clockwise by default.
+    local degrees = -90
+    -- If player is sneaking, reverse the rotation.
+    if minetest.is_player(puncher) and puncher:get_player_control().sneak then degrees = -degrees end
 
-        facedir = FACEDIR_LOOKUP[up_index][back_index]
-        if facedir == nil then minetest.chat_send_all("Could not look up facedir") end
-        node.param2 = facedir
-        minetest.set_node(pos, node)
-    end
+    rotate.rotate_node(pos, node, axis, degrees)
 end)

rotate.lua

@@ -0,0 +1,64 @@
+local math, ipairs
+    = math, ipairs
+
+local minetest, vector
+    = minetest, vector
+
+local rotate = {}
+
+-- Axis lookup table based on how Minetest's `facedir` operates.
+local AXIS_LOOKUP = {
+    vector.new( 0,  1,  0), -- +Y
+    vector.new( 0,  0,  1), -- +Z
+    vector.new( 0,  0, -1), -- -Z
+    vector.new( 1,  0,  0), -- +X
+    vector.new(-1,  0,  0), -- -X
+    vector.new( 0, -1,  0), -- -Y
+}
+
+-- Takes an axis vector and returns its index in the `AXIS_LOOKUP` table.
+-- Returns `nil` for any vector that is not a valid axis vector.
+local function axis_vector_to_index(vec)
+    if     vec.y ==  1 then if vec.x == 0 and vec.z == 0 then return 1 end
+    elseif vec.z ==  1 then if vec.x == 0 and vec.y == 0 then return 2 end
+    elseif vec.z == -1 then if vec.x == 0 and vec.y == 0 then return 3 end
+    elseif vec.x ==  1 then if vec.y == 0 and vec.z == 0 then return 4 end
+    elseif vec.x == -1 then if vec.y == 0 and vec.z == 0 then return 5 end
+    elseif vec.y == -1 then if vec.x == 0 and vec.z == 0 then return 6 end
+    else return nil end
+end
+
+local FACEDIR_LOOKUP = {}
+for up_index, up in ipairs(AXIS_LOOKUP) do
+    FACEDIR_LOOKUP[up_index] = {}
+    for rot = 0, 3 do
+        local facedir = (up_index - 1) * 4 + rot
+        local back = minetest.facedir_to_dir(facedir)
+        local back_index = axis_vector_to_index(back)
+        FACEDIR_LOOKUP[up_index][back_index] = facedir
+    end
+end
+
+-- Rotates `node` at the specified `pos` around `axis` by `degrees` counter-clockwise.
+local function rotate_node(pos, node, axis, degrees)
+    if degrees % 90 ~= 0 then error("degrees must be divisible by 90") end
+    if axis_vector_to_index(axis) == nil then error("axis must be an axis vector") end
+
+    local def = minetest.registered_nodes[node.name]
+    if def.paramtype2 ~= "facedir" then error("node's paramtype2 is not 'facedir'") end
+
+    local up   = AXIS_LOOKUP[1 + math.floor(node.param2 / 4)]
+    local back = minetest.facedir_to_dir(node.param2)
+
+    up   = up  :rotate_around_axis(axis, math.rad(degrees)):round()
+    back = back:rotate_around_axis(axis, math.rad(degrees)):round()
+
+    local up_index   = axis_vector_to_index(up)
+    local back_index = axis_vector_to_index(back)
+
+    node.param2 = FACEDIR_LOOKUP[up_index][back_index]
+    minetest.set_node(pos, node)
+end
+rotate.rotate_node = rotate_node
+
+return rotate

utility.lua

@@ -0,0 +1,16 @@
+local ipairs, tostring
+    = ipairs, tostring
+
+local minetest
+    = minetest
+
+local utility = {}
+
+local function debug_tell(...)
+    local text = ""
+    for _, v in ipairs({...}) do text = text .. tostring(v) end
+    minetest.chat_send_all(text)
+end
+utility.debug_tell = debug_tell
+
+return utility