mirror of
https://github.com/Dadido3/noita-mapcap.git
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66 lines
1.2 KiB
Lua
66 lines
1.2 KiB
Lua
-- Copyright (c) 2019-2022 David Vogel
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--
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-- This software is released under the MIT License.
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-- https://opensource.org/licenses/MIT
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---@class HilbertLib
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local Hilbert = {}
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---Rotate/flip quadrant.
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---@param n integer
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---@param x integer
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---@param y integer
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---@param rx boolean
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---@param ry boolean
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---@return integer
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---@return integer
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local function hilbertRotate(n, x, y, rx, ry)
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if not ry then
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if rx then
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x = n - 1 - x
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y = n - 1 - y
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end
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x, y = y, x
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end
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return x, y
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end
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---Maps t in the range of [0, (2^potSize)^2-1] to a position on the hilbert curve with the side length of 2^potSize (Power of two size).
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---@param t integer
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---@param potSize integer
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---@return integer
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---@return integer
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function Hilbert.Map(t, potSize)
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local size = math.pow(2, potSize)
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local x, y = 0, 0
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if t < 0 or t >= size * size then
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error("variable t is outside of the range")
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end
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for i = 0, potSize - 1, 1 do
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local iPOT = math.pow(2, i)
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local rx = bit.band(t, 2) == 2
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local ry = bit.band(t, 1) == 1
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if rx then
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ry = not ry
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end
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x, y = hilbertRotate(iPOT, x, y, rx, ry)
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if rx then
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x = x + iPOT
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end
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if ry then
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y = y + iPOT
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end
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t = math.floor(t / 4)
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end
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return x, y
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end
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return Hilbert
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