💿🐜 Antkeeper source code
https://antkeeper.com
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207 lines
4.9 KiB
207 lines
4.9 KiB
/*
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* Copyright (C) 2021 Christopher J. Howard
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*
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* This file is part of Antkeeper source code.
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*
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* Antkeeper source code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Antkeeper source code is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef ANTKEEPER_GEOM_MORTON_HPP
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#define ANTKEEPER_GEOM_MORTON_HPP
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#include <array>
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#include <cstdlib>
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namespace geom {
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/// Morton location code encoding and decoding functions.
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namespace morton {
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/**
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* Encodes 2D coordinates as a Morton location code.
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*
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* @param[in] x X-coordinate to encode.
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* @param[in] y Y-coordinate to encode.
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* @return Morton location code.
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*/
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template <typename T>
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T encode(T x, T y);
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/**
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* Encodes 3D coordinates as a Morton location code.
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*
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* @param[in] x X-coordinate to encode.
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* @param[in] y Y-coordinate to encode.
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* @param[in] z Z-coordinate to encode.
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* @return Morton location code.
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*/
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template <typename T>
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T encode(T x, T y, T z);
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/**
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* Decodes 2D coordinates from a Morton location code.
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*
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* @param[in] code Morton location code to decode.
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* @param[out] x Decoded x-coordinate.
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* @param[out] y Decoded y-coordinate.
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*/
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template <typename T>
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void decode(T code, T& x, T& y);
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/**
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* Decodes 3D coordinates from a Morton location code.
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*
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* @param[in] code Morton location code to decode.
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* @param[out] x Decoded x-coordinate.
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* @param[out] y Decoded y-coordinate.
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* @param[out] z Decoded z-coordinate.
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*/
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template <typename T>
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void decode(T code, T& x, T& y, T& z);
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template <typename T>
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T encode(T x, T y)
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{
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auto expand = [](T x) -> T
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{
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x &= (1 << (sizeof(T) << 2)) - 1;
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if constexpr(sizeof(T) >= 8)
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x = (x ^ (x << 16)) & T(0x0000ffff0000ffff);
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if constexpr(sizeof(T) >= 4)
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x = (x ^ (x << 8)) & T(0x00ff00ff00ff00ff);
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if constexpr(sizeof(T) >= 2)
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x = (x ^ (x << 4)) & T(0x0f0f0f0f0f0f0f0f);
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x = (x ^ (x << 2)) & T(0x3333333333333333);
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x = (x ^ (x << 1)) & T(0x5555555555555555);
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return x;
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};
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return expand(x) | (expand(y) << 1);
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}
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template <typename T>
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T encode(T x, T y, T z)
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{
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auto expand = [](T x) -> T
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{
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if constexpr(sizeof(T) == 1)
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{
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x &= 0x3;
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x = (x | x << 2) & 0x9;
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}
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else if constexpr(sizeof(T) == 2)
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{
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x &= 0x001f;
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x = (x | x << 8) & 0x100f;
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x = (x | x << 4) & 0x10c3;
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x = (x | x << 2) & 0x1249;
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}
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else if constexpr(sizeof(T) == 4)
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{
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x &= 0x00003ff;
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x = (x | x << 16) & 0x30000ff;
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x = (x | x << 8) & 0x300f00f;
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x = (x | x << 4) & 0x30c30c3;
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x = (x | x << 2) & 0x9249249;
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}
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else if constexpr(sizeof(T) == 8)
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{
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x &= 0x00000000001fffff;
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x = (x | x << 32) & 0x001f00000000ffff;
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x = (x | x << 16) & 0x001f0000ff0000ff;
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x = (x | x << 8) & 0x100f00f00f00f00f;
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x = (x | x << 4) & 0x10c30c30c30c30c3;
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x = (x | x << 2) & 0x1249249249249249;
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}
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return x;
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};
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return expand(x) | (expand(y) << 1) | (expand(z) << 2);
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}
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template <typename T>
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void decode(T code, T& x, T& y)
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{
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auto compress = [](T x) -> T
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{
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x &= T(0x5555555555555555);
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x = (x ^ (x >> 1)) & T(0x3333333333333333);
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x = (x ^ (x >> 2)) & T(0x0f0f0f0f0f0f0f0f);
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if constexpr(sizeof(T) >= 2)
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x = (x ^ (x >> 4)) & T(0x00ff00ff00ff00ff);
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if constexpr(sizeof(T) >= 4)
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x = (x ^ (x >> 8)) & T(0x0000ffff0000ffff);
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if constexpr(sizeof(T) >= 8)
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x = (x ^ (x >> 16)) & T(0x00000000ffffffff);
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return x;
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};
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x = compress(code);
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y = compress(code >> 1);
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}
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template <typename T>
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void decode(T code, T& x, T& y, T& z)
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{
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auto compress = [](T x) -> T
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{
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if constexpr(sizeof(T) == 1)
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{
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x &= 0x9;
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x = (x ^ x >> 2) & 0x3;
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}
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else if constexpr(sizeof(T) == 2)
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{
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x &= 0x1249;
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x = (x ^ x >> 2) & 0x10c3;
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x = (x ^ x >> 4) & 0x100f;
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x = (x ^ x >> 8) & 0x001f;
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}
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else if constexpr(sizeof(T) == 4)
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{
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x &= 0x9249249;
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x = (x ^ x >> 2) & 0x30c30c3;
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x = (x ^ x >> 4) & 0x300f00f;
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x = (x ^ x >> 8) & 0x30000ff;
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x = (x ^ x >> 16) & 0x00003ff;
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}
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else if constexpr(sizeof(T) == 8)
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{
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x &= 0x1249249249249249;
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x = (x ^ x >> 2) & 0x10c30c30c30c30c3;
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x = (x ^ x >> 4) & 0x100f00f00f00f00f;
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x = (x ^ x >> 8) & 0x001f0000ff0000ff;
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x = (x ^ x >> 16) & 0x001f00000000ffff;
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x = (x ^ x >> 32) & 0x00000000001fffff;
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}
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return x;
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};
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x = compress(code);
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y = compress(code >> 1);
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z = compress(code >> 2);
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}
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} // namespace morton
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} // namespace geom
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#endif // ANTKEEPER_GEOM_MORTON_HPP
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