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Add a switch to QgsTessellator to avoid z handling and fallback to a

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purely 2d tesselation

Optimises tessellation when only a 2d tessellation is required by
skipping unnecessary/unwanted calculations
This commit is contained in:
Nyall Dawson 2019-09-30 09:43:45 +10:00
parent 8adc498421
commit 9b07075fae
4 changed files with 44 additions and 18 deletions
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4
python/core/auto_generated/qgstessellator.sip.in
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@ -32,12 +32,14 @@ Optionally provides extrusion by adding triangles that serve as walls when extru
Creates tessellator with a specified origin point of the world (in map coordinates)
%End
QgsTessellator( const QgsRectangle &bounds, bool addNormals, bool invertNormals = false, bool addBackFaces = false );
QgsTessellator( const QgsRectangle &bounds, bool addNormals, bool invertNormals = false, bool addBackFaces = false, bool noZ = false );
%Docstring
Creates tessellator with a specified ``bounds`` of input geometry coordinates.
This constructor allows the tessellator to map input coordinates to a desirable range for numerically
stability during calculations.
If ``noZ`` is ``True``, then a 2-dimensional tesselation only will be performed and all z coordinates will be ignored.
.. versionadded:: 3.10
%End

35
src/core/qgstessellator.cpp
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@ -78,13 +78,14 @@ QgsTessellator::QgsTessellator( double originX, double originY, bool addNormals,
init();
}
QgsTessellator::QgsTessellator( const QgsRectangle &bounds, bool addNormals, bool invertNormals, bool addBackFaces )
QgsTessellator::QgsTessellator( const QgsRectangle &bounds, bool addNormals, bool invertNormals, bool addBackFaces, bool noZ )
: mBounds( bounds )
, mOriginX( mBounds.xMinimum() )
, mOriginY( mBounds.yMinimum() )
, mAddNormals( addNormals )
, mInvertNormals( invertNormals )
, mAddBackFaces( addBackFaces )
, mNoZ( noZ )
{
init();
}
@ -227,7 +228,7 @@ struct float_pair_hash
}
};
static void _ringToPoly2tri( const QgsLineString *ring, std::vector<p2t::Point *> &polyline, QHash<p2t::Point *, float> &zHash )
static void _ringToPoly2tri( const QgsLineString *ring, std::vector<p2t::Point *> &polyline, QHash<p2t::Point *, float> *zHash )
{
const int pCount = ring->numPoints();
@ -242,7 +243,6 @@ static void _ringToPoly2tri( const QgsLineString *ring, std::vector<p2t::Point *
{
const float x = *srcXData++;
const float y = *srcYData++;
const float z = *srcZData++;
auto res = foundPoints.insert( std::make_pair( x, y ) );
if ( !res.second )
@ -253,7 +253,10 @@ static void _ringToPoly2tri( const QgsLineString *ring, std::vector<p2t::Point *
p2t::Point *pt2 = new p2t::Point( x, y );
polyline.push_back( pt2 );
zHash[pt2] = z;
if ( zHash )
{
( *zHash )[pt2] = *srcZData++;
}
}
}
@ -421,7 +424,7 @@ void QgsTessellator::addPolygon( const QgsPolygon &polygon, float extrusionHeigh
{
const QgsLineString *exterior = qgsgeometry_cast< const QgsLineString * >( polygon.exteriorRing() );
const QVector3D pNormal = _calculateNormal( exterior, mOriginX, mOriginY, mInvertNormals );
const QVector3D pNormal = !mNoZ ? _calculateNormal( exterior, mOriginX, mOriginY, mInvertNormals ) : QVector3D();
const int pCount = exterior->numPoints();
if ( pCount == 4 && polygon.numInteriorRings() == 0 )
@ -429,10 +432,10 @@ void QgsTessellator::addPolygon( const QgsPolygon &polygon, float extrusionHeigh
// polygon is a triangle - write vertices to the output data array without triangulation
const double *xData = exterior->xData();
const double *yData = exterior->yData();
const double *zData = exterior->zData();
const double *zData = !mNoZ ? exterior->zData() : nullptr;
for ( int i = 0; i < 3; i++ )
{
mData << *xData++ - mOriginX << *zData++ << - *yData++ + mOriginY;
mData << *xData++ - mOriginX << ( mNoZ ? 0 : *zData++ ) << - *yData++ + mOriginY;
if ( mAddNormals )
mData << pNormal.x() << pNormal.z() << - pNormal.y();
}
@ -442,7 +445,7 @@ void QgsTessellator::addPolygon( const QgsPolygon &polygon, float extrusionHeigh
// the same triangle with reversed order of coordinates and inverted normal
for ( int i = 2; i >= 0; i-- )
{
mData << exterior->xAt( i ) - mOriginX << exterior->zAt( i ) << - exterior->yAt( i ) + mOriginY;
mData << exterior->xAt( i ) - mOriginX << ( mNoZ ? 0 : exterior->zAt( i ) ) << - exterior->yAt( i ) + mOriginY;
if ( mAddNormals )
mData << -pNormal.x() << -pNormal.z() << pNormal.y();
}
@ -450,11 +453,11 @@ void QgsTessellator::addPolygon( const QgsPolygon &polygon, float extrusionHeigh
}
else
{
if ( !qgsDoubleNear( pNormal.length(), 1, 0.001 ) )
if ( !mNoZ && !qgsDoubleNear( pNormal.length(), 1, 0.001 ) )
return; // this should not happen - pNormal should be normalized to unit length
std::unique_ptr<QMatrix4x4> toNewBase, toOldBase;
if ( pNormal != QVector3D( 0, 0, 1 ) )
if ( !mNoZ && pNormal != QVector3D( 0, 0, 1 ) )
{
// this is not a horizontal plane - need to reproject the polygon to a new base so that
// we can do the triangulation in a plane
@ -524,7 +527,7 @@ void QgsTessellator::addPolygon( const QgsPolygon &polygon, float extrusionHeigh
// polygon exterior
std::vector<p2t::Point *> polyline;
_ringToPoly2tri( qgsgeometry_cast< const QgsLineString * >( polygonNew->exteriorRing() ), polyline, z );
_ringToPoly2tri( qgsgeometry_cast< const QgsLineString * >( polygonNew->exteriorRing() ), polyline, mNoZ ? nullptr : &z );
polylinesToDelete << polyline;
std::unique_ptr<p2t::CDT> cdt( new p2t::CDT( polyline ) );
@ -535,7 +538,7 @@ void QgsTessellator::addPolygon( const QgsPolygon &polygon, float extrusionHeigh
std::vector<p2t::Point *> holePolyline;
const QgsLineString *hole = qgsgeometry_cast< const QgsLineString *>( polygonNew->interiorRing( i ) );
_ringToPoly2tri( hole, holePolyline, z );
_ringToPoly2tri( hole, holePolyline, mNoZ ? nullptr : &z );
cdt->AddHole( holePolyline );
polylinesToDelete << holePolyline;
@ -555,12 +558,12 @@ void QgsTessellator::addPolygon( const QgsPolygon &polygon, float extrusionHeigh
for ( int j = 0; j < 3; ++j )
{
p2t::Point *p = t->GetPoint( j );
QVector4D pt( p->x, p->y, z[p], 0 );
QVector4D pt( p->x, p->y, mNoZ ? 0 : z[p], 0 );
if ( toOldBase )
pt = *toOldBase * pt;
const double fx = ( pt.x() / scaleX ) - mOriginX + pt0.x();
const double fy = ( pt.y() / scaleY ) - mOriginY + pt0.y();
const double fz = pt.z() + extrusionHeight + pt0.z();
const double fz = mNoZ ? 0 : ( pt.z() + extrusionHeight + pt0.z() );
mData << fx << fz << -fy;
if ( mAddNormals )
mData << pNormal.x() << pNormal.z() << - pNormal.y();
@ -572,12 +575,12 @@ void QgsTessellator::addPolygon( const QgsPolygon &polygon, float extrusionHeigh
for ( int j = 2; j >= 0; --j )
{
p2t::Point *p = t->GetPoint( j );
QVector4D pt( p->x, p->y, z[p], 0 );
QVector4D pt( p->x, p->y, mNoZ ? 0 : z[p], 0 );
if ( toOldBase )
pt = *toOldBase * pt;
const double fx = ( pt.x() / scaleX ) - mOriginX + pt0.x();
const double fy = ( pt.y() / scaleY ) - mOriginY + pt0.y();
const double fz = pt.z() + extrusionHeight + pt0.z();
const double fz = mNoZ ? 0 : ( pt.z() + extrusionHeight + pt0.z() );
mData << fx << fz << -fy;
if ( mAddNormals )
mData << -pNormal.x() << -pNormal.z() << pNormal.y();

6
src/core/qgstessellator.h
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@ -47,9 +47,12 @@ class CORE_EXPORT QgsTessellator
* Creates tessellator with a specified \a bounds of input geometry coordinates.
* This constructor allows the tessellator to map input coordinates to a desirable range for numerically
* stability during calculations.
*
* If \a noZ is TRUE, then a 2-dimensional tesselation only will be performed and all z coordinates will be ignored.
*
* \since QGIS 3.10
*/
QgsTessellator( const QgsRectangle &bounds, bool addNormals, bool invertNormals = false, bool addBackFaces = false );
QgsTessellator( const QgsRectangle &bounds, bool addNormals, bool invertNormals = false, bool addBackFaces = false, bool noZ = false );
//! Tessellates a triangle and adds its vertex entries to the output data array
void addPolygon( const QgsPolygon &polygon, float extrusionHeight );
@ -82,6 +85,7 @@ class CORE_EXPORT QgsTessellator
bool mAddBackFaces = false;
QVector<float> mData;
int mStride;
bool mNoZ = false;
};
#endif // QGSTESSELLATOR_H

17
tests/src/3d/testqgstessellator.cpp
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@ -101,6 +101,7 @@ bool checkTriangleOutput( const QVector<float> &data, bool withNormals, const QL
TriangleCoords out( dataRaw, withNormals );
if ( exp != out )
{
qDebug() << i;
qDebug() << "expected:";
exp.dump();
qDebug() << "got:";
@ -136,6 +137,7 @@ class TestQgsTessellator : public QObject
void testCrashSelfIntersection();
void testCrashEmptyPolygon();
void testBoundsScaling();
void testNoZ();
private:
};
@ -369,6 +371,21 @@ void TestQgsTessellator::testBoundsScaling()
QVERIFY( checkTriangleOutput( t2.data(), true, tc ) );
}
void TestQgsTessellator::testNoZ()
{
// test tessellation with no z support
QgsPolygon polygonZ;
polygonZ.fromWkt( "POLYGONZ((1 1 1, 2 1 1, 3 2 1, 1 2 1, 1 1 1))" );
QList<TriangleCoords> tc;
tc << TriangleCoords( QVector3D( 0, 1, 0 ), QVector3D( 1, 0, 0 ), QVector3D( 2, 1, 0 ) );
tc << TriangleCoords( QVector3D( 0, 1, 0 ), QVector3D( 0, 0, 0 ), QVector3D( 1, 0, 0 ) );
QgsTessellator t( polygonZ.boundingBox(), false, false, false, true );
t.addPolygon( polygonZ, 0 );
QVERIFY( checkTriangleOutput( t.data(), false, tc ) );
}
QGSTEST_MAIN( TestQgsTessellator )
#include "testqgstessellator.moc"