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n/b/worley: performance improvements

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This commit is contained in:
Danny Robson 2015-06-01 15:34:33 +10:00
parent 9b548e56d9
commit 19def9d4fe
2 changed files with 32 additions and 40 deletions
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70
noise/basis/worley.cpp
View File

@ -23,92 +23,84 @@ using util::noise::basis::worley;
///////////////////////////////////////////////////////////////////////////////
template <typename T>
util::vector<2,T>
generate (util::point<2,T> p, uint64_t seed)
util::point<2,T>
generate (util::point<2,intmax_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> {
auto r = util::point<2,T> {
(u & 0xffff) / T{0xffff},
(v & 0xffff) / T{0xffff}
} * 2 - 1;
CHECK_GE (r, T{-1});
CHECK_LE (r, T{ 1});
};
CHECK_LIMIT (r, T{0}, T{1});
return r;
}
///////////////////////////////////////////////////////////////////////////////
template <typename T>
worley<T>::worley (seed_t _seed):
template <typename T, size_t F>
worley<T,F>::worley (seed_t _seed):
seed (_seed)
{ ; }
//-----------------------------------------------------------------------------
template <typename T>
worley<T>::worley ():
seed (time (nullptr))
template <typename T, size_t F>
worley<T,F>::worley ():
worley (time (nullptr))
{ ; }
//-----------------------------------------------------------------------------
template <typename T>
template <typename T, size_t F>
util::range<T>
worley<T>::bounds (void) const
worley<T,F>::bounds (void) const
{
return { 0.0, 1.5 };
}
//-----------------------------------------------------------------------------
template <typename T>
template <typename T, size_t F>
T
worley<T>::operator() (util::point<2,T> p) const
worley<T,F>::operator() (util::point<2,T> p) const
{
// extract integer and fractional parts. be careful to always round down
// (particularly with negatives) and avoid rounding errors.
auto p_int = p.template cast<intmax_t> ();
if (p.x < 0) p_int.x -= 1;
if (p.y < 0) p_int.y -= 1;
auto p_rem = abs (p - p_int);
auto p_rem = abs (p - p_int).template as<point> ();
// +---+---+---+
// | 0 | 1 | 2 |
// +---+---+---+
// | 3 | 4 | 5 |
// +---+-------+
// | 6 | 7 | 8 |
// +---+---+---+
T distances[9] = { std::numeric_limits<T>::quiet_NaN () };
// setup an array of distances
static constexpr size_t RADIUS = 1;
static constexpr size_t COUNT = pow2 (RADIUS * 2 + 1);
T distances[COUNT] = { 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};
// record the distances to each candidate point
for (signed y_off = -signed(RADIUS); y_off <= signed(RADIUS) ; ++y_off) {
for (signed x_off = -signed(RADIUS); x_off <= signed(RADIUS); ++x_off) {
auto off = vector<2,intmax_t> {x_off, y_off};
auto pos = generate<T> (p_int + off, this->seed);
CHECK (off.x >= 0 && off.x <= 1);
CHECK (off.y >= 0 && off.y <= 1);
CHECK_LIMIT (pos.x, T{0}, T{1});
CHECK_LIMIT (pos.y, T{0}, T{1});
pos += off;
*cursor = distance2 (pos + off, p_rem);
cursor++;
}
}
std::sort (std::begin (distances), std::end (distances));
CHECK_GE (distances[0], 0);
CHECK (bounds ().contains (distances[0]));
return distances[0];
// find the f'th lowest value
static_assert (F < COUNT, "worley order must be less than search radius");
std::partial_sort (distances, distances + F, distances + COUNT);
CHECK_GE (distances[F], 0);
return distances[F];
}

2
noise/basis/worley.hpp
View File

@ -23,7 +23,7 @@
#include "../../range.hpp"
namespace util { namespace noise { namespace basis {
template <typename T>
template <typename T, size_t F = 0>
struct worley {
worley (seed_t);
worley ();