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n/fractal: add musgrave's hybrid multi fractal

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This commit is contained in:
Danny Robson 2015-05-27 01:16:58 +10:00
parent 1c9c38e9a7
commit 46a87c0b11
2 changed files with 82 additions and 6 deletions
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54
noise/fractal.cpp
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@ -25,6 +25,7 @@
using util::noise::fractal;
using util::noise::fbm;
using util::noise::rmf;
using util::noise::hmf;
///////////////////////////////////////////////////////////////////////////////
@ -167,7 +168,7 @@ template <typename T, typename B>
T
rmf<T,B>::operator() (T x, T y) const {
const T offset = 1;
const T H = 1;
const T H = 1.f;
T exponents[octaves];
for (size_t i = 0; i < octaves; ++i)
@ -220,3 +221,54 @@ template struct util::noise::rmf<double, util::noise::gradient<double,util::lerp
template struct util::noise::rmf<double, util::noise::value<double,util::lerp::linear>>;
template struct util::noise::rmf<double, util::noise::value<double,util::lerp::quintic>>;
//-----------------------------------------------------------------------------
template <typename T, typename B>
hmf<T,B>::hmf ():
H (0.25f),
octaves (6),
frequency (0.1f),
lacunarity (2),
offset (0.7f),
amplitude (1),
gain (1)
{ ; }
//-----------------------------------------------------------------------------
template <typename T, typename B>
T
hmf<T,B>::operator() (T x, T y) const
{
T exponents[octaves];
for (size_t i = 0; i < octaves; ++i)
exponents[i] = std::pow (std::pow (lacunarity, float (i)), -H);
T result = 0;
T signal = 0;
T weight = 1;
x *= frequency;
y *= frequency;
for (size_t i = 0; i < octaves; ++i) {
signal = (basis (x, y) + offset) * exponents[i];
result += weight * signal;
weight *= gain * signal;
if (weight > 1)
weight = 1;
x *= lacunarity;
y *= lacunarity;
}
return result;
}
template struct util::noise::hmf<float, util::noise::cellular<float>>;
template struct util::noise::hmf<float, util::noise::gradient<float,util::lerp::linear>>;
template struct util::noise::hmf<float, util::noise::gradient<float,util::lerp::quintic>>;
template struct util::noise::hmf<float, util::noise::value<float,util::lerp::linear>>;
template struct util::noise::hmf<float, util::noise::value<float,util::lerp::quintic>>;

34
noise/fractal.hpp
View File

@ -93,11 +93,11 @@ namespace util {
static constexpr T DEFAULT_GAIN = 2;
rmf (unsigned octaves,
T frequency,
T lacunarity,
T amplitude,
T gain,
seed_t seed);
T frequency,
T lacunarity,
T amplitude,
T gain,
seed_t seed);
rmf ();
unsigned octaves;
@ -111,6 +111,30 @@ namespace util {
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;
};
}
}