libcruft-util/noise/fractal.cpp

135 lines
3.5 KiB
C++

/*
* This file is part of libgim.
*
* libgim is free software: you can redistribute it and/or modify it under the
* terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later
* version.
*
* libgim is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with libgim. If not, see <http://www.gnu.org/licenses/>.
*
* Copyright 2012 Danny Robson <danny@nerdcruft.net>
*/
#include "noise/fractal.hpp"
#include "debug.hpp"
#include <algorithm>
///////////////////////////////////////////////////////////////////////////////
util::noise::fractal::fractal (unsigned _octaves,
double _frequency,
double _lacunarity):
octaves (_octaves),
frequency (_frequency),
lacunarity (_lacunarity)
{ ; }
util::noise::fractal::fractal ()
{ ;}
util::noise::fractal::~fractal ()
{ ; }
double
util::noise::fractal::eval (double, double) const
{ unreachable (); }
///////////////////////////////////////////////////////////////////////////////
template <typename B>
util::noise::fbm<B>::fbm ()
{ ; }
template <typename B>
double
util::noise::fbm<B>::eval (double x, double y) const {
double total = 0.0;
double f = this->frequency;
double a = 1.0;
double a_sum = 0.0;
for (size_t i = 0; i < this->octaves; ++i) {
total += basis.eval (x * f, y * f) * a;
f *= 2.0;
a_sum += a;
a *= this->lacunarity;
}
return total;
}
template struct util::noise::fbm<util::noise::cellular>;
template struct util::noise::fbm<util::noise::gradient<lerp::linear>>;
template struct util::noise::fbm<util::noise::gradient<lerp::quintic>>;
template struct util::noise::fbm<util::noise::value<lerp::linear>>;
template struct util::noise::fbm<util::noise::value<lerp::quintic>>;
///////////////////////////////////////////////////////////////////////////////
template <typename B>
util::noise::musgrave<B>::musgrave ()
{ ; }
template <typename B>
double
util::noise::musgrave<B>::eval (double x, double y) const {
double total = 0.0;
double f = this->frequency;
double a = 1.0;
double weight = 1.0;
double offset = 1.0;
double gain = 2.0;
double signal;
signal = basis.eval (x * f, y * f);
signal = fabs (signal);
signal = offset - signal;
signal *= signal;
total = signal;
for (size_t i = 1; i < this->octaves; ++i) {
f *= 2.0;
a *= this->lacunarity;
weight = signal * gain;
weight = max (0.0, min (1.0, weight));
signal = basis.eval (x * f, y * f);
signal = fabs (signal);
signal = offset - signal;
signal *= signal;
signal *= weight;
total += signal * a;
total = min (1.0, max (0.0, total));
}
return total;
}
template struct util::noise::musgrave<util::noise::cellular>;
template struct util::noise::musgrave<util::noise::gradient<lerp::linear>>;
template struct util::noise::musgrave<util::noise::gradient<lerp::quintic>>;
template struct util::noise::musgrave<util::noise::value<lerp::linear>>;
template struct util::noise::musgrave<util::noise::value<lerp::quintic>>;