libcruft-util/noise/fractal/rmf.ipp

103 lines
2.9 KiB
Plaintext
Raw Normal View History

/*
* 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_FRACTAL_RMF_IPP
#error
#endif
#define __UTIL_NOISE_FRACTAL_RMF_IPP
namespace util { namespace noise { namespace fractal {
///////////////////////////////////////////////////////////////////////////
template <typename T, typename B>
rmf<T,B>::rmf (unsigned _octaves,
T _H,
T _offset,
T _frequency,
T _lacunarity,
T _amplitude,
T _gain,
seed_t _seed):
seed (_seed),
octaves (_octaves),
H (_H),
offset (_offset),
frequency (_frequency),
lacunarity (_lacunarity),
amplitude (_amplitude),
gain (_gain),
basis (_seed),
invAH (std::pow (amplitude, -H)),
invGH (std::pow (gain, H))
{ ; }
//-------------------------------------------------------------------------
template <typename T, typename B>
rmf<T,B>::rmf ():
rmf<T,B> (DEFAULT_OCTAVES,
DEFAULT_H,
DEFAULT_OFFSET,
DEFAULT_FREQUENCY,
DEFAULT_LACUNARITY,
DEFAULT_AMPLITUDE,
DEFAULT_GAIN,
rand ())
{ ; }
//-------------------------------------------------------------------------
// we use the name 'amplitude' instead of musgrave's 'gain'.
// assumes basis distribution [-1,1] and offset ~= 1
template <typename T, typename B>
2015-06-01 18:45:47 +10:00
constexpr T
rmf<T,B>::operator() (util::point<2,T> p) const
{
T scale = invAH;
T signal = 0;
T result = 0;
T weight = 1;
p *= frequency;
for (size_t i = 0; i < octaves; ++i) {
// generates ridged noise
signal = basis (p);
signal = std::fabs (signal);
signal = offset - signal;
// sharpens the ridges
signal *= signal;
// influence by sharpness of previous iteration
signal *= weight;
// contribute to the weight
weight = signal * amplitude;
weight = limit (weight, 0, 1);
// record and continue
result += signal * scale;
scale *= invGH;
p *= lacunarity;
}
return result;
}
} } }