Add rotating by "pushing" on edges

- Move functionality to init.lua:
  - Player step event handling
  - Rotation state is stored in rotating_state
  - Calls hud.update_player_hud
- Punch node event uses rotating_state
- Add utility functions:
  - Rotate box by a specified facedir value
  - Find node's current (rotated) selection box
  - Find pointed-at node's closest edge

hud.lua

@@ -0,0 +1,37 @@
+local nodecore
+    = nodecore
+
+local LABEL_ROTATION_HINT = "rotation hint"
+
+local TEX_ROTATE_FACE = "nc_extended_rotating_hud_rotate_face.png"
+local TEX_ROTATE_EDGE = "nc_extended_rotating_hud_rotate_edge.png"
+
+local hud = {}
+
+local function crosshair_hud_element(texture)
+    return {
+        label = LABEL_ROTATION_HINT,
+        hud_elem_type = "image",
+        text = texture,
+        position  = { x = 0.5, y = 0.5 },
+        offset    = { x = 0, y = 0 },
+        alignment = { x = 0, y = 0 },
+        scale     = { x = 1, y = 1 },
+        quick = true
+    }
+end
+
+local function update_player_hud(player, state)
+    local mode = state and state.mode
+    if mode == "face" then
+        local texture = TEX_ROTATE_FACE
+        if state.invert then texture = texture .. "^[transformFX" end
+        texture = texture .. "^[opacity:" .. 192
+        nodecore.hud_set(player, crosshair_hud_element(texture))
+    else
+        nodecore.hud_set(player, { label = LABEL_ROTATION_HINT, ttl = 0 })
+    end
+end
+hud.update_player_hud = update_player_hud
+
+return hud

init.lua

@@ -1,20 +1,66 @@
-local minetest, vector, include
-    = minetest, vector, include
+local minetest, vector, nodecore, include
+    = minetest, vector, nodecore, include
 
-local rotate = include("rotate")
+local hud     = include("hud")
+local rotate  = include("rotate")
+local utility = include("utility")
 
-minetest.register_on_punchnode(function(pos, node, puncher, pointed_thing)
-    local def = minetest.registered_nodes[node.name]
-    if def.paramtype2 ~= "facedir" then return end
+-- TODO: Add crosshair indicators for rotating around edges.
+-- TODO: Register only the nodes that should be rotatable.
+-- TODO: Replace `on_rightclick` of intended nodes.
+-- TODO: Add some more comments.
+
+-- Distance at which we want to rotate by "pushing" on an edge.
+local EDGE_DISTANCE = 1.5 / 16 -- 1.5 texels (at 16² texture resolution)
+
+local rotating_state = {}
+
+nodecore.register_playerstep({
+    label = "extended rotating update",
+    action = function(player, player_data)
+        local name  = player:get_player_name()
+        local state = {}; rotating_state[name] = state
+
+        local pointed_thing = player_data.raycast()
+        if (not pointed_thing) or pointed_thing.type ~= "node" then return nil end
+
+        state.pos  = pointed_thing.under
+        state.node = minetest.get_node(state.pos)
+        if not rotate.is_rotatable(state.node) then return end
+
+        if vector.equals(pointed_thing.above, pointed_thing.under) then return end
+        state.face = pointed_thing.above - pointed_thing.under
 
-    -- 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 edge, distance = utility.find_closest_edge(state.node, pointed_thing)
+        if edge and distance > EDGE_DISTANCE then
+            state.axis = state.face
+            state.mode = "face"
+        else
+            state.axis = state.face:cross(edge):normalize():round()
+            state.mode = "edge"
+        end
+
+        state.invert = player:get_player_control().sneak
+        hud.update_player_hud(player, state)
+    end,
+})
+
+minetest.register_on_leaveplayer(function(player)
+    local name = player:get_player_name()
+    rotating_state[name] = nil
+end)
+
+
+minetest.register_on_punchnode(function(pos, node, puncher, pointed_thing)
+    if not minetest.is_player(puncher) then return end
+    local name  = puncher:get_player_name()
+    local state = rotating_state[name]
+    if not state then return end
 
-    -- 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
+    -- Make sure we're still the same node that we raycasted in `playerstep`.
+    if not vector.equals(pos, state.pos) then return end
+    if node.name ~= state.node.name or node.param2 ~= state.node.param2 then return end
 
-    rotate.rotate_node(pos, node, axis, degrees)
+    local degrees = state.invert and 90 or -90
+    rotate.rotate_node(state.pos, state.node, state.axis, degrees)
 end)

rotate.lua

@@ -1,6 +1,7 @@
-local math, ipairs
-    = math, ipairs
-
+local ipairs, unpack
+    = ipairs, unpack
+local math_min, math_max, math_floor, math_rad
+    = math.min, math.max, math.floor, math.rad
 local minetest, vector
     = minetest, vector
 
@@ -16,6 +17,16 @@ local AXIS_LOOKUP = {
     vector.new( 0, -1,  0), -- -Y
 }
 
+-- Lookup table to find out how to rotate for each `facedir` axis.
+local AXIS_ROTATION = {
+    nil, -- No rotation.
+    { vector.new(1, 0, 0),  90 },
+    { vector.new(1, 0, 0), -90 },
+    { vector.new(0, 0, 1), -90 },
+    { vector.new(0, 0, 1),  90 },
+    { vector.new(0, 0, 1), 180 },
+}
+
 -- 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)
@@ -39,19 +50,50 @@ for up_index, up in ipairs(AXIS_LOOKUP) do
     end
 end
 
+-- Returns whether the specified `node` is rotatable by this mod.
+local function is_rotatable(node)
+    local name = node and node.name
+    local def  = minetest.registered_nodes[name]
+    return def and def.paramtype2 == "facedir"
+end
+rotate.is_rotatable = is_rotatable
+
+local function rotate_box_by_facedir(box, facedir)
+    if facedir == 0 then return end
+
+    local axis_index = math_floor(facedir / 4)
+    if axis_index ~= 0 then
+        local axis, degrees = unpack(AXIS_ROTATION[1 + axis_index])
+        box.min = box.min:rotate_around_axis(axis, math_rad(degrees))
+        box.max = box.max:rotate_around_axis(axis, math_rad(degrees))
+    end
+
+    local axis_rot = facedir % 4
+    if axis_rot ~= 0 then
+        local axis = AXIS_LOOKUP[1 + axis_index]
+        local degrees = axis_rot * 90
+        box.min = box.min:rotate_around_axis(axis, math_rad(degrees))
+        box.max = box.max:rotate_around_axis(axis, math_rad(degrees))
+    end
+
+    -- Recalculate the proper minimum and maximum bounds, since we just rotated these vectors.
+    box.min.x, box.max.x = math_min(box.min.x, box.max.x), math_max(box.min.x, box.max.x)
+    box.min.y, box.max.y = math_min(box.min.y, box.max.y), math_max(box.min.y, box.max.y)
+    box.min.z, box.max.z = math_min(box.min.z, box.max.z), math_max(box.min.z, box.max.z)
+end
+rotate.rotate_box_by_facedir = rotate_box_by_facedir
+
 -- 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
+    if not is_rotatable(node) then error("node is not rotatable") 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 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()
+    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)

utility.lua

@@ -1,16 +1,67 @@
-local ipairs, tostring
-    = ipairs, tostring
 
-local minetest
-    = minetest
+local math_abs, math_sign
+    = math.abs, math.sign
+local minetest, vector, include
+    = minetest, vector, include
+
+local rotate = include("rotate")
 
 local utility = {}
 
-local function debug_tell(...)
-    local text = ""
-    for _, v in ipairs({...}) do text = text .. tostring(v) end
-    minetest.chat_send_all(text)
+-- Default selection boxes for a node that doesn't have one them explicitly.
+local DEFAULT_SELECTION_BOX = { min = vector.new(-0.5, -0.5, -0.5),
+                                max = vector.new( 0.5,  0.5,  0.5) }
+
+-- Gets the active `selection_box` for the specified `node` which
+-- has a `paramtype2` of `facedir`, based on its `param2` value.
+local function get_node_active_selection_box(node)
+    local def = minetest.registered_nodes[node.name]
+    local box = def.selection_box and def.selection_box.fixed
+    -- No need to rotate the default selection box.
+    if not box then return DEFAULT_SELECTION_BOX end
+    -- If node definition specifies multiple selection boxes, just pick the first (for now).
+    if type(box[1]) == "table" then box = box[1] end
+    -- Transform the `{ x1, y1, z1, x2, y2, z2 }` box to a `{ min, max }` one.
+    box = { min = vector.new(box[1], box[2], box[3]),
+            max = vector.new(box[4], box[5], box[6]) }
+    -- Rotate the box to face `facedir`.
+    rotate.rotate_box_by_facedir(box, node.param2)
+    return box
+end
+
+-- Finds the closest edge of the node the player is looking at as
+-- a vector pointing away from the center, and the distance to it.
+local function find_closest_edge(node, pointed_thing)
+    -- For this math to work, we assume that selection box is centered.
+    local max = get_node_active_selection_box(node).max
+    -- Point relative to the collision box we're pointing at.
+    local point = pointed_thing.intersection_point - pointed_thing.under
+
+    -- Find the edge we're closest to.
+    local vec = vector.zero()
+    if math_abs(point.y / point.x) > max.x / max.y then
+        vec.y = math_sign(point.y)
+        if math_abs(point.z / point.x) > max.x / max.z
+            then vec.z = math_sign(point.z)
+            else vec.x = math_sign(point.x)
+        end
+    else
+        vec.x = math_sign(point.x)
+        if math_abs(point.z / point.y) > max.y / max.z
+            then vec.z = math_sign(point.z)
+            else vec.y = math_sign(point.y)
+        end
+    end
+
+    local d = 1
+    local v = max - point:multiply(vec):apply(math_abs)
+    local EPSILON = tonumber("1.19e-07")
+    if math_abs(v.x) > EPSILON and v.x < d then d = v.x end
+    if math_abs(v.y) > EPSILON and v.y < d then d = v.y end
+    if math_abs(v.z) > EPSILON and v.z < d then d = v.z end
+
+    return vec, d
 end
-utility.debug_tell = debug_tell
+utility.find_closest_edge = find_closest_edge
 
 return utility