nc_extended_rotating/init.lua

local minetest, vector, nodecore, include
    = minetest, vector, nodecore, include
local math_round = math.round

local hud      = include("hud")
local rotate   = include("rotate")
local utility  = include("utility")
local registry = include("registry")

-- TODO: Add crosshair indicators for rotating around edges.
-- TODO: Add some more comments.
-- TODO: Add particles to preview rotation?

-- Distance at which we want to rotate by "pushing" on an edge.
local EDGE_DISTANCE = 2.5 / 16 -- texels (at 16² texture resolution)

-- Contains a per-player state that holds information, created by a raycast
-- done in `playerstep`, about the node this player might rotate. This is used
-- to update the their HUD and to decide what to do when a rightclick occurs.
local rotating_state = {}


local function handle_rotatable_rightclick(pos, node, clicker)
    local state = rotating_state[clicker:get_player_name()]
    if not state then return false end -- Not looking at anything rotatable.

    -- Make sure we're still the same node that we raycasted in `playerstep`.
    if not vector.equals(pos, state.pos) then return true end
    if node.name ~= state.node.name or node.param2 ~= state.node.param2 then return true end
    -- Only continue if the node can actually be sucessfully rotated.
    if not state.success then return true end

    rotate.rotate_node(pos, node, state.facedir)
    return true
end
registry.custom_on_rightclick = handle_rotatable_rightclick

-- Override `nc_scaling`'s default empty hand right-click behavior so we can use it
-- to rotate things when holding sneak, which doesn't trigger a node's `on_rightclick`.
local default_on_place = minetest.registered_items[""].on_place
minetest.registered_items[""].on_place = function(item_stack, placer, pointed_thing, ...)
    -- Player must sneak in order for this to run. Non-sneak is handled by node's `on_rightclick`.
    if pointed_thing.type == "node" and minetest.is_player(placer) and placer:get_player_control().sneak then
        local pos  = pointed_thing.under
        local node = minetest.get_node(pos)
        if handle_rotatable_rightclick(pos, node, placer) then return end
    end
    default_on_place(item_stack, placer, pointed_thing, ...)
end


-- Calculates the state for the specified `player` and player `data`.
-- This state contains information about how the player would rotate a block.
local function calculate_rotating_state(player, data)
    local state = {}

    local pointed_thing = 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 registry.is_rotatable(state.node) then return nil end

    if vector.equals(pointed_thing.above, pointed_thing.under) then return nil end
    state.face = pointed_thing.above - pointed_thing.under

    -- When player is sneaking, must be empty-handed for rotating to work.
    local is_sneaking = player:get_player_control().sneak
    if is_sneaking and (not player:get_wielded_item():is_empty()) then return nil end

    local degrees = 90
    local r = utility.rotation_vector_from_lookat(state.node, pointed_thing, EDGE_DISTANCE)
    state.axis = r

    local num = math_round(r.x * r.x + r.y * r.y + r.z * r.z) -- Squared length.
    if     num == 1 then state.mode = "face"
    elseif num == 2 then state.mode = "edge"; state.axis = state.face:cross(r)
    elseif num == 3 then state.mode = "mirror"; degrees = 120
    end

    -- Sneaking causes the direction of the rotation to be inverted.
    if is_sneaking then degrees = -degrees end
    state.invert = is_sneaking

    state.facedir = rotate.rotate_facedir(state.node.param2, state.axis, -degrees)
    state.facedir = registry.fix_rotatable_facedir(state.node, state.facedir)
    state.success = state.facedir and state.facedir ~= state.node.param2

    return state
end

nodecore.register_playerstep({
    label = "extended rotating update",
    action = function(player, data)
        local name = player:get_player_name()
        rotating_state[name] = calculate_rotating_state(player, data)
        hud.update_player_hud(player, rotating_state[name])
    end,
})

minetest.register_on_leaveplayer(function(player)
    local name = player:get_player_name()
    rotating_state[name] = nil
end)