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