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ENH: reduce memory overhead in mergePoints (issue #495)

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- can avoid the intermediate point distance field in exchange for
  calculating a point subtraction twice.
This commit is contained in:
Mark Olesen
2017-06-12 14:36:45 +02:00
parent 39f0c4cf1a
commit 4094e2c58f
1 changed files with 32 additions and 29 deletions
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61
src/OpenFOAM/meshes/meshTools/mergePoints.C
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@ -41,22 +41,28 @@ Foam::label Foam::mergePoints
{
typedef typename PointList::value_type point_type;
// Create a old to new point mapping array
pointMap.setSize(points.size());
const label nPoints = points.size();
// Create an old to new point mapping array
pointMap.setSize(nPoints);
pointMap = -1;
if (points.empty())
if (!nPoints)
{
return 0;
}
// Explicitly convert to Field to support various list types
tmp<Field<point_type>> tPoints(new Field<point_type>(points));
point_type compareOrigin = origin;
if (origin == point_type::max)
{
compareOrigin = sum(tPoints())/points.size();
// Use average of input points to define a comparison origin.
// Same as sum(points)/nPoints, but handles different list types
compareOrigin = points[0];
for (label pointi=1; pointi < nPoints; ++pointi)
{
compareOrigin += points[pointi];
}
compareOrigin /= nPoints;
}
// We're comparing distance squared to origin first.
@ -68,34 +74,31 @@ Foam::label Foam::mergePoints
// x^2+y^2+z^2 + 2*mergeTol*(x+z+y) + mergeTol^2*...
// so the difference will be 2*mergeTol*(x+y+z)
const scalar mergeTolSqr = Foam::sqr(scalar(mergeTol));
const scalar mergeTolSqr = Foam::sqr(mergeTol);
// Sort points by magSqr
const Field<point_type> d(tPoints - compareOrigin);
List<scalar> magSqrD(d.size());
forAll(d, pointi)
List<scalar> magSqrDist(nPoints);
forAll(points, pointi)
{
magSqrD[pointi] = magSqr(d[pointi]);
magSqrDist[pointi] = magSqr(points[pointi] - compareOrigin);
}
labelList order;
Foam::sortedOrder(magSqrD, order);
Foam::sortedOrder(magSqrDist, order);
Field<scalar> sortedTol(points.size());
Field<scalar> sortedTol(nPoints);
forAll(order, sortI)
{
const label pointi = order[sortI];
const point_type& pt = points[order[sortI]];
// Convert to scalar precision
// NOTE: not yet using point_type template parameter
const point pt
(
scalar(d[pointi].x()),
scalar(d[pointi].y()),
scalar(d[pointi].z())
);
sortedTol[sortI] = 2*mergeTol*(mag(pt.x())+mag(pt.y())+mag(pt.z()));
// Use scalar precision
sortedTol[sortI] =
2*mergeTol*
(
mag(scalar(pt.x() - compareOrigin.x())),
+ mag(scalar(pt.y() - compareOrigin.y())),
+ mag(scalar(pt.z() - compareOrigin.z()))
);
}
label newPointi = 0;
@ -104,11 +107,11 @@ Foam::label Foam::mergePoints
label pointi = order[0];
pointMap[pointi] = newPointi++;
for (label sortI = 1; sortI < order.size(); sortI++)
for (label sortI = 1; sortI < order.size(); ++sortI)
{
// Get original point index
const label pointi = order[sortI];
const scalar mag2 = magSqrD[order[sortI]];
const scalar mag2 = magSqrDist[order[sortI]];
// Convert to scalar precision
// NOTE: not yet using point_type template parameter
@ -127,8 +130,8 @@ Foam::label Foam::mergePoints
(
label prevSortI = sortI - 1;
prevSortI >= 0
&& (mag(magSqrD[order[prevSortI]] - mag2) <= sortedTol[sortI]);
prevSortI--
&& (mag(magSqrDist[order[prevSortI]] - mag2) <= sortedTol[sortI]);
--prevSortI
)
{
const label prevPointi = order[prevSortI];