libcruft-util/noise/turbulence.hpp

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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>
*/
#ifndef __UTIL_NOISE_TURBULENCE_HPP
#define __UTIL_NOISE_TURBULENCE_HPP
#include "../point.hpp"
#include "../vector.hpp"
#include <cstdint>
namespace util { namespace noise {
/// perturb the evaluation point of a noise function by the results of
/// a per-dimension noise function
///
/// assumes the pertubation function is roughly symetrical around 0.
/// nothing will explode if it isn't, but you'll see strong directional
/// artefacts with higher scaling factors.
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template <
size_t S, // dimension
typename T, // value_type
typename D, // data fractal
typename P // pertubation fractal
>
struct turbulence {
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static constexpr auto dimension = S;
using value_type = T;
using seed_t = uint64_t;
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turbulence (seed_t, vector<S,T> scale);
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seed_t seed (seed_t);
seed_t seed (void) const;
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constexpr T operator() (point<S,T>) const;
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D data;
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// XXX: use a union to defer initialization of pertubation fractals in
// the constructor. i know this is horrible, but there's no time to
// write the proper generator constructor to pass out the seeds.
union {
char _[0];
P perturb[S];
};
vector<S,T> scale;
};
} }
#include "turbulence.ipp"
#endif