78 lines
2.2 KiB
C++
78 lines
2.2 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 2015-2017 Danny Robson <danny@nerdcruft.net>
|
|
*/
|
|
|
|
#ifndef __UTIL_GEOM_SAMPLE_HPP
|
|
#define __UTIL_GEOM_SAMPLE_HPP
|
|
|
|
#include "../coord/fwd.hpp"
|
|
#include "./ops.hpp"
|
|
|
|
#include <cstddef>
|
|
|
|
|
|
///////////////////////////////////////////////////////////////////////////////
|
|
namespace util::geom {
|
|
/// a function object that selects a uniformly random point inside a shape
|
|
/// using a provided random generator. the point will lie within the shape,
|
|
/// inclusive of boundaries.
|
|
///
|
|
/// may be specialised for arbitrary shapes but uses rejection sampling
|
|
/// as a safe default. this implies that execution may not take a constant
|
|
/// time.
|
|
///
|
|
/// \tparam S coordinate type dimension
|
|
/// \tparam T value type for the shape/coordinate
|
|
/// \tparam K the shape type to test
|
|
/// \tparam G a UniformRandomBitGenerator, eg std::min19937
|
|
template <
|
|
size_t S,
|
|
typename T,
|
|
template <size_t,typename> class K,
|
|
typename G
|
|
>
|
|
struct sampler {
|
|
static point<S,T>
|
|
fn (K<S,T> k, G &g)
|
|
{
|
|
auto b = bounds (k);
|
|
|
|
while (true) {
|
|
auto p = sample (b, g);
|
|
if (intersects (k, p))
|
|
return p;
|
|
}
|
|
}
|
|
};
|
|
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
/// a convenience function that calls sample::fn to select a random point
|
|
/// in a provided shape.
|
|
template <
|
|
size_t S,
|
|
typename T,
|
|
template <size_t,typename> class K,
|
|
typename G // random generator
|
|
>
|
|
point<S,T>
|
|
sample (K<S,T> k, G &g)
|
|
{
|
|
return sampler<S,T,K,G>::fn (k, g);
|
|
}
|
|
}
|
|
|
|
#endif
|