106 lines
3.2 KiB
C++
106 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 "value.hpp"
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#include "../../hash/murmur/murmur2.hpp"
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using util::noise::basis::value;
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///////////////////////////////////////////////////////////////////////////////
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// Generate a type from [-UNIT..UNIT]
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template <typename T>
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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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T v = mix (seed, mix (uint64_t (p.y), uint64_t (p.x))) & 0xffff;
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v = v / T{0xffff} * 2 - 1;
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CHECK_GE (v, T{0});
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CHECK_LE (v, T{1});
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return v;
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}
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///////////////////////////////////////////////////////////////////////////////
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template <typename T, util::noise::lerp_t<T> L>
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value<T,L>::value (seed_t _seed):
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seed (_seed)
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{ ; }
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//-----------------------------------------------------------------------------
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template <typename T, util::noise::lerp_t<T> L>
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value<T,L>::value ():
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seed (time (nullptr))
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{ ; }
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//-----------------------------------------------------------------------------
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template <typename T, util::noise::lerp_t<T> L>
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util::range<T>
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value<T,L>::bounds (void) const
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{
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return { -1, 1 };
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}
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//-----------------------------------------------------------------------------
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template <typename T, util::noise::lerp_t<T> L>
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T
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value<T,L>::operator() (util::point<2,T> p) const
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{
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auto p_int = p.template cast<intmax_t> ();
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auto p_rem = p - p_int;
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// Shift the coordinate system down a little to ensure we get unit weights
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// for the lerp. It's better to do this than abs the fractional portion so
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// we don't get reflections along the origin.
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if (p.x < 0) { p_rem.x = 1 + p_rem.x; p_int.x -= 1; }
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if (p.y < 0) { p_rem.y = 1 + p_rem.y; p_int.y -= 1; }
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// Generate the four corner values
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T p0 = generate<T> (p_int + util::vector<2,T>{ 0, 0 }, this->seed);
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T p1 = generate<T> (p_int + util::vector<2,T>{ 1, 0 }, this->seed);
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T p2 = generate<T> (p_int + util::vector<2,T>{ 0, 0 }, this->seed);
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T p3 = generate<T> (p_int + util::vector<2,T>{ 1, 1 }, this->seed);
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// Interpolate on one dimension, then the other.
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return L (L (p0, p1, p_rem.x),
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L (p2, p3, p_rem.x),
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p_rem.y);
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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 value<float, lerp::trunc>;
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template struct value<float, lerp::linear>;
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template struct value<float, lerp::cubic>;
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template struct value<float, lerp::quintic>;
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template struct value<double, lerp::trunc>;
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template struct value<double, lerp::linear>;
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template struct value<double, lerp::cubic>;
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template struct value<double, lerp::quintic>;
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} } }
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