libcruft-util/noise/fractal.hpp

167 lines
4.5 KiB
C++

/*
* 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 Danny Robson <danny@nerdcruft.net>
*/
#ifndef __UTIL_NOISE_FRACTAL_HPP
#define __UTIL_NOISE_FRACTAL_HPP
#include "basis.hpp"
namespace util {
namespace noise {
/// Base noise summation
template <typename T>
struct fractal {
using seed_t = uint64_t;
fractal (seed_t);
fractal ();
virtual ~fractal ();
virtual T operator() (T x, T y) const = 0;
seed_t seed;
};
/// Fractal Brownian Motion summation.
///
/// Sum progressive layers of a noise basis with scaling frequency
/// and amplitude.
///
/// octaves: count of layers to be summed
/// frequency: point scaling factor for the base octave
/// lacunarity: per octave frequency scaling factor
/// amplitude: maximum absolute value of the noise
/// gain: per octave amplitude scaling factor. typically 1/f.
template <typename T, typename B>
struct fbm : public fractal<T> {
using seed_t = typename basis<T>::seed_t;
static constexpr unsigned DEFAULT_OCTAVES = 8;
static constexpr T DEFAULT_FREQUENCY = T(0.1);
static constexpr T DEFAULT_LACUNARITY = 2;
static constexpr T DEFAULT_AMPLITUDE = 1;
static constexpr T DEFAULT_GAIN = 1 / T(2);
fbm (unsigned octaves,
T frequency,
T lacunarity,
T amplitude,
T gain,
seed_t seed);
fbm ();
unsigned octaves;
T frequency;
T lacunarity;
T amplitude;
T gain;
B basis;
virtual T operator() (T x, T y) const override;
};
/// Rigid Multifractal summation, based on Musgrave's algorithm
///
/// octaves: count of layers to be summed
/// frequency: point scaling factor for the base octave
/// lacunarity: per octave frequency scaling factor
template <typename T, typename B>
struct rmf : public fractal<T> {
using seed_t = typename basis<T>::seed_t;
static constexpr unsigned DEFAULT_OCTAVES = 5;
static constexpr T DEFAULT_FREQUENCY = T(1);
static constexpr T DEFAULT_LACUNARITY = 2;
static constexpr T DEFAULT_AMPLITUDE = 1;
static constexpr T DEFAULT_GAIN = 2;
rmf (unsigned octaves,
T frequency,
T lacunarity,
T amplitude,
T gain,
seed_t seed);
rmf ();
unsigned octaves;
T frequency;
T lacunarity;
T amplitude;
T gain;
B basis;
virtual T operator() (T x, T y) const override;
};
///////////////////////////////////////////////////////////////////////
template <typename T, typename B>
struct hmf : public fractal<T> {
using seed_t = typename basis<T>::seed_t;
hmf ();
T H;
unsigned octaves;
T frequency;
T lacunarity;
T offset;
T amplitude;
T gain;
B basis;
virtual T operator() (T x, T y) const override;
};
///////////////////////////////////////////////////////////////////////
/// Heterogeneous procedural terrain fucntion: stats by altitude method
template <typename T, typename B>
struct hetero : public fractal<T> {
using seed_t = typename basis<T>::seed_t;
hetero ();
T H;
unsigned octaves;
T frequency;
T lacunarity;
T offset;
T amplitude;
T gain;
B basis;
virtual T operator() (T x, T y) const override;
};
}
}
#endif