libcruft-util/noise/basis/expgrad.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_EXPGRAD_IPP
#error
#endif
#define __UTIL_NOISE_BASIS_EXPGRAD_IPP
#include "../rand.hpp"
namespace util { namespace noise { namespace basis {
///////////////////////////////////////////////////////////////////////////
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template <size_t S, typename T, util::noise::lerp_t<T> L
>
expgrad<S,T,L>::expgrad (seed_t _seed, T _base, T _exponent):
gradient<S,T,L> (_seed),
m_base (_base),
m_exponent (_exponent)
{ ; }
///////////////////////////////////////////////////////////////////////////
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template <size_t S, typename T, util::noise::lerp_t<T> L>
vector<S,T>
expgrad<S,T,L>::generate (pointi<S> p) const
{
auto t = (noise::rand<float> (this->seed (), p) + 1) / 2;
auto factor = std::pow (m_base, -t * m_exponent);
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return factor * gradient<S,T,L>::generate (p);
}
} } }