libcruft-util/noise/basis/worley.cpp

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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>
*/
#include "worley.hpp"
#include "../../hash/murmur/murmur2.hpp"
using util::noise::basis::worley;
///////////////////////////////////////////////////////////////////////////////
template <typename T>
util::vector<2,T>
generate (util::point<2,T> p, uint64_t seed)
{
using util::hash::murmur2::mix;
auto u = mix (seed, mix (uint64_t (p.x), uint64_t (p.y)));
auto v = mix (u, seed);
auto r = util::vector<2,T> {
(u & 0xffff) / T{0xffff},
(v & 0xffff) / T{0xffff}
} * 2 - 1;
CHECK_GE (r, T{-1});
CHECK_LE (r, T{ 1});
return r;
}
///////////////////////////////////////////////////////////////////////////////
template <typename T>
worley<T>::worley (seed_t _seed):
seed (_seed)
{ ; }
//-----------------------------------------------------------------------------
template <typename T>
worley<T>::worley ():
seed (time (nullptr))
{ ; }
//-----------------------------------------------------------------------------
template <typename T>
util::range<T>
worley<T>::bounds (void) const
{
return { 0.0, 1.5 };
}
//-----------------------------------------------------------------------------
template <typename T>
T
worley<T>::operator() (util::point<2,T> p) const
{
auto p_int = p.template cast<intmax_t> ();
auto p_rem = p - p_int;
// Generate the four corner values. It's not strictly necessary to
// normalise the values, but we get a more consistent and visually
// appealing range of outputs with normalised values.
if (p.x < 0) { p_rem.x = 1 + p_rem.x; p_int.x -= 1; }
if (p.y < 0) { p_rem.y = 1 + p_rem.y; p_int.y -= 1; }
// +---+---+---+
// | 0 | 1 | 2 |
// +---+---+---+
// | 3 | 4 | 5 |
// +---+-------+
// | 6 | 7 | 8 |
// +---+---+---+
T distances[9] = { std::numeric_limits<T>::quiet_NaN () };
T *cursor = distances;
for (signed y_off = -1; y_off <= 1 ; ++y_off)
for (signed x_off = -1; x_off <= 1; ++x_off) {
auto pos = vector<2,T> (T (x_off), T (y_off));
auto off = generate<T> (p_int + pos, this->seed);
off += T{1};
off /= T{2};
CHECK (off.x >= 0 && off.x <= 1);
CHECK (off.y >= 0 && off.y <= 1);
pos += off;
*cursor++ = pos.difference2 (p_rem);
}
std::sort (std::begin (distances), std::end (distances));
CHECK_GE (distances[0], 0);
CHECK (bounds ().contains (distances[0]));
return distances[0];
}
///////////////////////////////////////////////////////////////////////////////
#include "../lerp.hpp"
namespace util { namespace noise { namespace basis {
template struct worley<float>;
template struct worley<double>;
} } }