120 lines
3.2 KiB
C++
120 lines
3.2 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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#include "worley.hpp"
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#include "../../hash/murmur/murmur2.hpp"
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using util::noise::basis::worley;
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///////////////////////////////////////////////////////////////////////////////
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template <typename T>
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util::vector<2,T>
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generate (util::point<2,T> p, uint64_t seed)
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{
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using util::hash::murmur2::mix;
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auto u = mix (seed, mix (uint64_t (p.x), uint64_t (p.y)));
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auto v = mix (u, seed);
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auto r = util::vector<2,T> {
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(u & 0xffff) / T{0xffff},
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(v & 0xffff) / T{0xffff}
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} * 2 - 1;
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CHECK_GE (r, T{-1});
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CHECK_LE (r, T{ 1});
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return r;
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}
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///////////////////////////////////////////////////////////////////////////////
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template <typename T>
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worley<T>::worley (seed_t _seed):
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seed (_seed)
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{ ; }
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//-----------------------------------------------------------------------------
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template <typename T>
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worley<T>::worley ():
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seed (time (nullptr))
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{ ; }
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//-----------------------------------------------------------------------------
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template <typename T>
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util::range<T>
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worley<T>::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>
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T
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worley<T>::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 = abs (p - p_int);
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// +---+---+---+
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// | 0 | 1 | 2 |
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// +---+---+---+
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// | 3 | 4 | 5 |
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// +---+-------+
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// | 6 | 7 | 8 |
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// +---+---+---+
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T distances[9] = { std::numeric_limits<T>::quiet_NaN () };
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T *cursor = distances;
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for (signed y_off = -1; y_off <= 1 ; ++y_off)
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for (signed x_off = -1; x_off <= 1; ++x_off) {
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auto pos = vector<2,T> (T (x_off), T (y_off));
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auto off = generate<T> (p_int + pos, this->seed);
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off += T{1};
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off /= T{2};
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CHECK (off.x >= 0 && off.x <= 1);
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CHECK (off.y >= 0 && off.y <= 1);
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pos += off;
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*cursor++ = pos.difference2 (p_rem.template as<util::vector> ());
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}
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std::sort (std::begin (distances), std::end (distances));
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CHECK_GE (distances[0], 0);
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CHECK (bounds ().contains (distances[0]));
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return distances[0];
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}
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///////////////////////////////////////////////////////////////////////////////
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#include "../lerp.hpp"
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namespace util { namespace noise { namespace basis {
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template struct worley<float>;
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template struct worley<double>;
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} } }
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