libcruft-util/noise/basis/perlin.ipp

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/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Copyright 2012-2015 Danny Robson <danny@nerdcruft.net>
*/
#ifdef __UTIL_NOISE_BASIS_PERLIN_IPP
#error
#endif
#define __UTIL_NOISE_BASIS_PERLIN_IPP
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#include "../../types.hpp"
namespace util { namespace noise { namespace basis {
///////////////////////////////////////////////////////////////////////////
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template <size_t S, typename T, util::noise::lerp_t<T> L, template <size_t,typename,lerp_t<T>> class G>
perlin<S,T,L,G>::perlin (seed_t _seed):
G<S,T,L> (_seed)
{ ; }
//-------------------------------------------------------------------------
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template <size_t S, typename T, util::noise::lerp_t<T> L, template <size_t,typename,lerp_t<T>> class G>
util::range<T>
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perlin<S,T,L,G>::bounds (void) const
{
return {
-std::sqrt (T{2}) / 2,
std::sqrt (T{2}) / 2
};
}
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//-------------------------------------------------------------------------
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template <size_t S, typename T, util::noise::lerp_t<T> L, template <size_t,typename,lerp_t<T>> class G>
T
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perlin<S,T,L,G>::operator() (util::point<S,T> p) const
{
// extract integer and fractional parts. be careful to always round down
auto p_int = floor (p).template cast<intmax_t> ();
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auto p_rem = p - p_int;
// generate the corner positions
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pointi<S> p_[pow(2,S)];
std::transform (std::begin (this->CORNERS), std::end (this->CORNERS),
std::begin (p_),
[p_int] (auto i) { return i + p_int; });
// generate the corner gradients
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vector<S,T> g_[pow(2,S)];
std::transform (std::begin (p_), std::end (p_),
std::begin (g_),
[this] (auto i) { return this->generate (i); });
// compute the dot products
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T v_[pow(2,S)];
for (size_t i = 0; i < elems (v_); ++i)
v_[i] = dot (g_[i], p - p_[i]);
// interpolate the results
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T l_[pow(2,S)];
std::copy (std::begin (v_), std::end (v_), std::begin (l_));
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for (size_t i = S; i; --i)
for (size_t j = 0; j < std::pow(2,i); j += 2)
l_[j / 2] = L (l_[j], l_[j+1], p_rem[S-i]);
return l_[0];
}
} } }