assimp/code/SpatialSort.cpp

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/*
---------------------------------------------------------------------------
Free Asset Import Library (ASSIMP)
---------------------------------------------------------------------------
Copyright (c) 2006-2008, ASSIMP Development Team
All rights reserved.
Redistribution and use of this software in source and binary forms,
with or without modification, are permitted provided that the following
conditions are met:
* Redistributions of source code must retain the above
copyright notice, this list of conditions and the
following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the
following disclaimer in the documentation and/or other
materials provided with the distribution.
* Neither the name of the ASSIMP team, nor the names of its
contributors may be used to endorse or promote products
derived from this software without specific prior
written permission of the ASSIMP Development Team.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
---------------------------------------------------------------------------
*/
/** @file Implementation of the helper class to quickly find vertices close to a given position */
#include <algorithm>
#include "SpatialSort.h"
using namespace Assimp;
// ------------------------------------------------------------------------------------------------
// Constructs a spatially sorted representation from the given position array.
SpatialSort::SpatialSort( const aiVector3D* pPositions, unsigned int pNumPositions, unsigned int pElementOffset)
{
// define the reference plane. We choose some arbitrary vector away from all basic axises
// in the hope that no model spreads all its vertices along this plane.
mPlaneNormal.Set( 0.8523f, 0.34321f, 0.5736f);
mPlaneNormal.Normalize();
// store references to all given positions along with their distance to the reference plane
mPositions.reserve( pNumPositions);
for( unsigned int a = 0; a < pNumPositions; a++)
{
const char* tempPointer = reinterpret_cast<const char*> (pPositions);
const aiVector3D* vec = reinterpret_cast<const aiVector3D*> (tempPointer + a * pElementOffset);
// store position by index and distance
float distance = *vec * mPlaneNormal;
mPositions.push_back( Entry( a, *vec, distance));
}
// now sort the array ascending by distance.
std::sort( mPositions.begin(), mPositions.end());
}
// ------------------------------------------------------------------------------------------------
// Destructor
SpatialSort::~SpatialSort()
{
// nothing to do here, everything destructs automatically
}
// ------------------------------------------------------------------------------------------------
// Returns an iterator for all positions close to the given position.
void SpatialSort::FindPositions( const aiVector3D& pPosition, float pRadius, std::vector<unsigned int>& poResults) const
{
float dist = pPosition * mPlaneNormal;
float minDist = dist - pRadius, maxDist = dist + pRadius;
// clear the array in this strange fashion because a simple clear() would also deallocate
// the array which we want to avoid
poResults.erase( poResults.begin(), poResults.end());
// quick check for positions outside the range
if( mPositions.size() == 0)
return;
if( maxDist < mPositions.front().mDistance)
return;
if( minDist > mPositions.back().mDistance)
return;
// do a binary search for the minimal distance to start the iteration there
unsigned int index = mPositions.size() / 2;
unsigned int binaryStepSize = mPositions.size() / 4;
while( binaryStepSize > 1)
{
if( mPositions[index].mDistance < minDist)
index += binaryStepSize;
else
index -= binaryStepSize;
binaryStepSize /= 2;
}
// depending on the direction of the last step we need to single step a bit back or forth
// to find the actual beginning element of the range
while( index > 0 && mPositions[index].mDistance > minDist)
index--;
while( index < (mPositions.size() - 1) && mPositions[index].mDistance < minDist)
index++;
// Mow start iterating from there until the first position lays outside of the distance range.
// Add all positions inside the distance range within the given radius to the result aray
std::vector<Entry>::const_iterator it = mPositions.begin() + index;
float squareEpsilon = pRadius * pRadius;
while( it->mDistance < maxDist)
{
if( (it->mPosition - pPosition).SquareLength() < squareEpsilon)
poResults.push_back( it->mIndex);
++it;
if( it == mPositions.end())
break;
}
// that's it
}