122 lines
3.7 KiB
C++
122 lines
3.7 KiB
C++
/*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* Copyright 2014-2015 Danny Robson <danny@nerdcruft.net>
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*/
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#include "maths.hpp"
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#include <algorithm>
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namespace util {
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///------------------------------------------------------------------------
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/// expand point to use homogenous coordinates of a higher dimension.
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/// ie, fill with (0,..,0,1)
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template <size_t S, typename T>
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template <size_t D>
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point<D,T>
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point<S,T>::homog (void) const
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{
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static_assert (D > S, "homog will not overwrite data");
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point<D,T> out;
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// Copy the existing data
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auto c = std::copy (this->begin (),
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this->end (),
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out.begin ());
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// Fill until the second last element with zeros
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auto f = std::fill_n (c, D - S - 1, T{0});
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// Last element should be one
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*f = T{1};
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return out;
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}
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//-------------------------------------------------------------------------
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template <size_t S, typename T, typename U>
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constexpr typename std::common_type<T,U>::type
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distance (point<S,T> a, point<S,U> b)
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{
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using type_t = typename std::common_type<T,U>::type;
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static_assert (std::is_floating_point<type_t>::value,
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"sqrt likely requires fractional types");
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return std::sqrt (distance2 (a, b));
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}
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//-------------------------------------------------------------------------
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template <size_t S, typename T, typename U>
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constexpr typename std::common_type<T,U>::type
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distance2 (point<S,T> a, point<S,U> b)
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{
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typename std::common_type<T,U>::type sum {0};
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for (size_t i = 0; i < S; ++i)
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sum += pow2 (a.data[i] - b.data[i]);
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return sum;
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}
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//-------------------------------------------------------------------------
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template <size_t S, typename T, typename U>
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constexpr typename std::common_type<T,U>::type
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octile (point<S,T> a, point<S,U> b)
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{
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using type_t = typename std::common_type<T,U>::type;
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static_assert (!std::is_integral<type_t>::value,
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"octile requires more than integer precision");
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const type_t D1 = 1;
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const type_t D2 = std::sqrt (type_t {2});
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auto diff = util::abs (a - b);
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// distance for axis-aligned walks
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auto axis = D1 * (diff.x + diff.y);
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// the savings from diagonal walks
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auto diag = (D2 - 2 * D1) * util::min (diff);
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return axis + diag;
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}
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//-------------------------------------------------------------------------
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template <size_t S, typename T, typename U>
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constexpr typename std::common_type<T,U>::type
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manhattan (point<S,T> a, point<S,U> b)
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{
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typename std::common_type<T,U>::type sum {0};
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for (size_t i = 0; i < S; ++i)
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sum += util::abs (a.data[i] - b.data[i]);
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return sum;
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}
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//-------------------------------------------------------------------------
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template <size_t S, typename T, typename U>
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constexpr typename std::common_type<T,U>::type
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chebyshev(point<S,T> a, point<S,U> b)
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{
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return util::max (abs (a - b));
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}
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}
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