121 lines
3.6 KiB
C++
121 lines
3.6 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 2012-2015 Danny Robson <danny@nerdcruft.net>
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*/
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#ifdef __UTIL_NOISE_BASIS_WORLEY_IPP
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#error
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#endif
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#define __UTIL_NOISE_BASIS_WORLEY_IPP
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#include "../../debug.hpp"
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#include "../../hash/murmur/murmur2.hpp"
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namespace util { namespace noise { namespace basis {
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///////////////////////////////////////////////////////////////////////////
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template <typename T, size_t F>
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worley<T,F>::worley (seed_t _seed):
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m_seed (_seed)
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{ ; }
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//-------------------------------------------------------------------------
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template <typename T, size_t F>
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util::range<T>
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worley<T,F>::bounds (void) const
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{
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return { 0.0, 1.5 };
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}
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//-------------------------------------------------------------------------
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template <typename T, size_t F>
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seed_t
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worley<T,F>::seed (void) const
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{
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return m_seed;
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}
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//-------------------------------------------------------------------------
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template <typename T, size_t F>
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seed_t
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worley<T,F>::seed (seed_t _seed)
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{
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return m_seed = _seed;
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}
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//-------------------------------------------------------------------------
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template <typename T, size_t F>
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T
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worley<T,F>::operator() (util::point<2,T> p) const
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{
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// extract integer and fractional parts. be careful to always round down
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// (particularly with negatives) and avoid rounding errors.
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auto p_int = p.template cast<intmax_t> ();
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if (p.x < 0) p_int.x -= 1;
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if (p.y < 0) p_int.y -= 1;
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auto p_rem = (p - p_int).template as<point> ();
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// setup an array of distances
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constexpr size_t RADIUS = 1;
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constexpr size_t COUNT = pow2 (RADIUS * 2 + 1);
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T distances[COUNT] = { std::numeric_limits<T>::quiet_NaN () };
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T *cursor = distances;
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// record the distances to each candidate point
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for (signed y_off = -signed(RADIUS); y_off <= signed(RADIUS) ; ++y_off) {
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for (signed x_off = -signed(RADIUS); x_off <= signed(RADIUS); ++x_off) {
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auto off = vector<2,intmax_t> {x_off, y_off};
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auto pos = generate (p_int + off);
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CHECK_LIMIT (pos.x, T{0}, T{1});
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CHECK_LIMIT (pos.y, T{0}, T{1});
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*cursor = distance2 (pos + off, p_rem);
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cursor++;
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}
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}
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// find the f'th lowest value
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static_assert (F < COUNT, "worley order must be less than search radius");
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std::partial_sort (distances, distances + F, distances + COUNT);
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CHECK_GE (distances[F], 0);
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return distances[F];
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}
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//////////////////////////////////////////////////////////////////////////
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template <typename T, size_t F>
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point<2,T>
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worley<T,F>::generate (point<2,intmax_t> p) const
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{
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using util::hash::murmur2::mix;
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auto u = mix (m_seed, mix (uint64_t (p.x), uint64_t (p.y)));
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auto v = mix (u, m_seed);
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auto r = util::point<2,T> {
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(u & 0xffff) / T{0xffff},
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(v & 0xffff) / T{0xffff}
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};
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CHECK_LIMIT (r, T{0}, T{1});
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return r;
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}
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} } }
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