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permutation.h
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permutation.h
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// ======================================================================== //
// Copyright 2009-2013 Intel Corporation //
// //
// 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. //
// ======================================================================== //
#ifndef __EMBREE_PERMUTATION_H__
#define __EMBREE_PERMUTATION_H__
#include "sys/platform.h"
#include "random.h"
#include <algorithm>
namespace embree
{
/*! Random permutation. */
class Permutation
{
public:
/*! Creates a random permutation. Uses system random number generator. */
Permutation(int size)
{
elts = size;
perm = new int[elts];
for (int i=0; i<elts; i++) perm[i] = i;
for (int i=0; i<elts; i++) std::swap(perm[i],perm[random<uint32>()%elts]);
}
/*! Creates a random permutation. Random number generator is provided as argument. */
Permutation(int size, Random& rng)
{
elts = size;
perm = new int[elts];
for (int i=0; i<elts; i++) perm[i] = i;
for (int i=0; i<elts; i++) std::swap(perm[i],perm[rng.getInt(elts)]);
}
/*! Destroys the permutation. */
~Permutation() {
if (perm) delete[] perm; perm = NULL;
}
/*! Returns the size of the permutation. */
__forceinline int size() const {
return elts;
}
/*! Returns the i'th element of the permutation. */
__forceinline int operator[](int i) const {
assert(i >= 0 && i < elts);
return perm[i];
}
private:
int elts; //!< Size of the permutation.
int* perm; //!< Array storing the permutation.
};
}
#endif