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// Geometric Tools, LLC
// Copyright (c) 1998-2014
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
//
// File Version: 5.0.1 (2010/10/01)
#include "Wm5PhysicsPCH.h"
#include "Wm5IntervalManager.h"
namespace Wm5
{
//----------------------------------------------------------------------------
template <typename Real>
IntervalManager<Real>::IntervalManager (
std::vector<Vector2<Real> >& interval)
:
mInterval(&interval)
{
Initialize();
}
//----------------------------------------------------------------------------
template <typename Real>
IntervalManager<Real>::~IntervalManager ()
{
}
//----------------------------------------------------------------------------
template <typename Real>
void IntervalManager<Real>::Initialize ()
{
// Get the interval endpoints.
int intrSize = (int)mInterval->size(), endpSize = 2*intrSize;
mEndpoint.resize(endpSize);
int i, j;
for (i = 0, j = 0; i < intrSize; ++i)
{
Endpoint& emin = mEndpoint[j++];
emin.Type = 0;
emin.Value = (*mInterval)[i][0];
emin.Index = i;
Endpoint& emax = mEndpoint[j++];
emax.Type = 1;
emax.Value = (*mInterval)[i][1];
emax.Index = i;
}
// Sort the interval endpoints.
std::sort(mEndpoint.begin(), mEndpoint.end());
// Create the interval-to-endpoint lookup table.
mLookup.resize(endpSize);
for (j = 0; j < endpSize; ++j)
{
Endpoint& endpoint = mEndpoint[j];
mLookup[2*endpoint.Index + endpoint.Type] = j;
}
// Active set of intervals (stored by index in array).
std::set<int> active;
// Set of overlapping intervals (stored by pairs of indices in array).
mOverlap.clear();
// Sweep through the endpoints to determine overlapping intervals.
for (i = 0; i < endpSize; ++i)
{
Endpoint& endpoint = mEndpoint[i];
int index = endpoint.Index;
if (endpoint.Type == 0) // an interval 'begin' value
{
std::set<int>::iterator iter = active.begin();
std::set<int>::iterator end = active.end();
for (/**/; iter != end; ++iter)
{
int activeIndex = *iter;
if (activeIndex < index)
{
mOverlap.insert(EdgeKey(activeIndex, index));
}
else
{
mOverlap.insert(EdgeKey(index, activeIndex));
}
}
active.insert(index);
}
else // an interval 'end' value
{
active.erase(index);
}
}
}
//----------------------------------------------------------------------------
template <typename Real>
void IntervalManager<Real>::SetInterval (int i, Real minValue,
Real maxValue)
{
assertion(0 <= i && i < (int)mInterval->size(), "Invalid index\n");
(*mInterval)[i][0] = minValue;
(*mInterval)[i][1] = maxValue;
mEndpoint[mLookup[2*i]].Value = minValue;
mEndpoint[mLookup[2*i+1]].Value = maxValue;
}
//----------------------------------------------------------------------------
template <typename Real>
void IntervalManager<Real>::GetInterval (int i, Real& minValue,
Real& maxValue) const
{
assertion(0 <= i && i < (int)mInterval->size(), "Invalid index\n");
minValue = (*mInterval)[i][0];
maxValue = (*mInterval)[i][1];
}
//----------------------------------------------------------------------------
template <typename Real>
void IntervalManager<Real>::Update ()
{
// Apply an insertion sort. Under the assumption that the intervals
// have not changed much since the last call, the end points are nearly
// sorted. The insertion sort should be very fast in this case.
int endpSize = (int)mEndpoint.size();
for (int j = 1; j < endpSize; ++j)
{
Endpoint key = mEndpoint[j];
int i = j - 1;
while (i >= 0 && key < mEndpoint[i])
{
Endpoint e0 = mEndpoint[i];
Endpoint e1 = mEndpoint[i+1];
// Update the overlap status.
if (e0.Type == 0)
{
if (e1.Type == 1)
{
// The 'b' of interval E0.mIndex was smaller than the 'e'
// of interval E1.mIndex, and the intervals *might have
// been* overlapping. Now 'b' and 'e' are swapped, and
// the intervals cannot overlap. Remove the pair from
// the overlap set. The removal operation needs to find
// the pair and erase it if it exists. Finding the pair
// is the expensive part of the operation, so there is no
// time savings in testing for existence first and then
// deleting.
mOverlap.erase(EdgeKey(e0.Index, e1.Index));
}
}
else
{
if (e1.Type == 0)
{
// The 'b' of interval E1.index was larger than the 'e'
// of interval E0.index, and the intervals were not
// overlapping. Now 'b' and 'e' are swapped, and the
// intervals *might be* overlapping. Determine if they
// are overlapping and then insert.
const Vector2<Real>& i0 = (*mInterval)[e0.Index];
const Vector2<Real>& i1 = (*mInterval)[e1.Index];
if (i0[0] <= i1[1])
{
mOverlap.insert(EdgeKey(e0.Index, e1.Index));
}
}
}
// Reorder the items to maintain the sorted list.
mEndpoint[i] = e1;
mEndpoint[i+1] = e0;
mLookup[2*e1.Index + e1.Type] = i;
mLookup[2*e0.Index + e0.Type] = i+1;
i--;
}
mEndpoint[i+1] = key;
mLookup[2*key.Index + key.Type] = i+1;
}
}
//----------------------------------------------------------------------------
template <typename Real>
const std::set<EdgeKey>& IntervalManager<Real>::GetOverlap () const
{
return mOverlap;
}
//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
// IntervalManager::Endpoint
//----------------------------------------------------------------------------
template <typename Real>
bool IntervalManager<Real>::Endpoint::operator< (const Endpoint& endpoint)
const
{
if (Value < endpoint.Value)
{
return true;
}
if (Value > endpoint.Value)
{
return false;
}
return Type < endpoint.Type;
}
//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
// Explicit instantiation.
//----------------------------------------------------------------------------
template WM5_PHYSICS_ITEM
class IntervalManager<float>;
template WM5_PHYSICS_ITEM
class IntervalManager<double>;
//----------------------------------------------------------------------------
}
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