qgstriangle.cpp

Go to the documentation of this file.

/***************************************************************************
                         qgstriangle.cpp
                         -------------------
    begin                : January 2017
    copyright            : (C) 2017 by Loïc Bartoletti
    email                : lbartoletti at tuxfamily dot org
 ***************************************************************************/
 
/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
 
#include "qgstriangle.h"
#include "qgsgeometryutils.h"
#include "qgslinestring.h"
#include "qgswkbptr.h"
 
#include <memory>
 
QgsTriangle::QgsTriangle()
{
  mWkbType = Qgis::WkbType::Triangle;
}
 
QgsTriangle::QgsTriangle( const QgsPoint &p1, const QgsPoint &p2, const QgsPoint &p3 )
{
  mWkbType = Qgis::WkbType::Triangle;
 
  const QVector< double > x { p1.x(), p2.x(), p3.x(), p1.x() };
  const QVector< double > y { p1.y(), p2.y(), p3.y(), p1.y() };
  QVector< double > z;
  if ( p1.is3D() )
  {
    z = { p1.z(), p2.z(), p3.z(), p1.z() };
  }
  QVector< double > m;
  if ( p1.isMeasure() )
  {
    m = {p1.m(), p2.m(), p3.m(), p1.m() };
  }
  setExteriorRing( new QgsLineString( x, y, z, m ) );
}
 
QgsTriangle::QgsTriangle( const QgsPointXY &p1, const QgsPointXY &p2, const QgsPointXY &p3 )
{
  mWkbType = Qgis::WkbType::Triangle;
 
  const QVector< double > x { p1.x(), p2.x(), p3.x(), p1.x() };
  const QVector< double > y {p1.y(), p2.y(), p3.y(), p1.y() };
  QgsLineString *ext = new QgsLineString( x, y );
  setExteriorRing( ext );
}
 
QgsTriangle::QgsTriangle( const QPointF p1, const QPointF p2, const QPointF p3 )
{
  mWkbType = Qgis::WkbType::Triangle;
 
  const QVector< double > x{ p1.x(), p2.x(), p3.x(), p1.x() };
  const QVector< double > y{ p1.y(), p2.y(), p3.y(), p1.y() };
  QgsLineString *ext = new QgsLineString( x, y );
  setExteriorRing( ext );
}
 
bool QgsTriangle::operator==( const QgsTriangle &other ) const
{
  if ( isEmpty() && other.isEmpty() )
  {
    return true;
  }
  else if ( isEmpty() || other.isEmpty() )
  {
    return false;
  }
 
  return ( ( vertexAt( 0 ) == other.vertexAt( 0 ) ) &&
           ( vertexAt( 1 ) == other.vertexAt( 1 ) ) &&
           ( vertexAt( 2 ) == other.vertexAt( 2 ) )
         );
}
 
bool QgsTriangle::operator!=( const QgsTriangle &other ) const
{
  return !operator==( other );
}
 
QString QgsTriangle::geometryType() const
{
  return QStringLiteral( "Triangle" );
}
 
QgsTriangle *QgsTriangle::createEmptyWithSameType() const
{
  auto result = std::make_unique< QgsTriangle >();
  result->mWkbType = mWkbType;
  return result.release();
}
 
void QgsTriangle::clear()
{
  QgsPolygon::clear();
  mWkbType = Qgis::WkbType::Triangle;
}
 
QgsTriangle *QgsTriangle::clone() const
{
  return new QgsTriangle( *this );
}
 
bool QgsTriangle::fromWkb( QgsConstWkbPtr &wkbPtr )
{
  clear();
  if ( !wkbPtr )
  {
    return false;
  }
 
  const Qgis::WkbType type = wkbPtr.readHeader();
  if ( QgsWkbTypes::flatType( type ) != Qgis::WkbType::Triangle )
  {
    return false;
  }
  mWkbType = type;
 
  Qgis::WkbType ringType;
  switch ( mWkbType )
  {
    case Qgis::WkbType::TriangleZ:
      ringType = Qgis::WkbType::LineStringZ;
      break;
    case Qgis::WkbType::TriangleM:
      ringType = Qgis::WkbType::LineStringM;
      break;
    case Qgis::WkbType::TriangleZM:
      ringType = Qgis::WkbType::LineStringZM;
      break;
    default:
      ringType = Qgis::WkbType::LineString;
      break;
  }
 
  int nRings;
  wkbPtr >> nRings;
  if ( nRings > 1 )
  {
    return false;
  }
 
  QgsLineString *line = new QgsLineString();
  line->fromWkbPoints( ringType, wkbPtr );
  mExteriorRing.reset( line );
 
  return true;
}
 
bool QgsTriangle::fromWkt( const QString &wkt )
{
  clear();
 
  const QPair<Qgis::WkbType, QString> parts = QgsGeometryUtils::wktReadBlock( wkt );
 
  if ( QgsWkbTypes::geometryType( parts.first ) != Qgis::GeometryType::Polygon )
    return false;
 
  mWkbType = parts.first;
 
  QString secondWithoutParentheses = parts.second;
  secondWithoutParentheses = secondWithoutParentheses.simplified().remove( ' ' );
  if ( ( parts.second.compare( QLatin1String( "EMPTY" ), Qt::CaseInsensitive ) == 0 ) ||
       secondWithoutParentheses.isEmpty() )
    return true;
 
  const QString defaultChildWkbType = QStringLiteral( "LineString%1%2" ).arg( is3D() ? QStringLiteral( "Z" ) : QString(), isMeasure() ? QStringLiteral( "M" ) : QString() );
 
  const QStringList blocks = QgsGeometryUtils::wktGetChildBlocks( parts.second, defaultChildWkbType );
  for ( const QString &childWkt : blocks )
  {
    const QPair<Qgis::WkbType, QString> childParts = QgsGeometryUtils::wktReadBlock( childWkt );
 
    const Qgis::WkbType flatCurveType = QgsWkbTypes::flatType( childParts.first );
 
    if ( flatCurveType == Qgis::WkbType::LineString )
      mInteriorRings.append( new QgsLineString() );
    else
    {
      clear();
      return false;
    }
    if ( !mInteriorRings.back()->fromWkt( childWkt ) )
    {
      clear();
      return false;
    }
  }
 
  mExteriorRing.reset( mInteriorRings.takeFirst() );
  if ( ( mExteriorRing->numPoints() < 3 ) || ( mExteriorRing->numPoints() > 4 ) || ( mExteriorRing->numPoints() == 4 && mExteriorRing->startPoint() != mExteriorRing->endPoint() ) )
  {
    clear();
    return false;
  }
 
  //scan through rings and check if dimensionality of rings is different to CurvePolygon.
  //if so, update the type dimensionality of the CurvePolygon to match
  bool hasZ = false;
  bool hasM = false;
  if ( mExteriorRing )
  {
    hasZ = hasZ || mExteriorRing->is3D();
    hasM = hasM || mExteriorRing->isMeasure();
  }
  if ( hasZ )
    addZValue( 0 );
  if ( hasM )
    addMValue( 0 );
 
  return true;
}
 
QDomElement QgsTriangle::asGml3( QDomDocument &doc, int precision, const QString &ns, const AxisOrder axisOrder ) const
{
 
  QDomElement elemTriangle = doc.createElementNS( ns, QStringLiteral( "Triangle" ) );
 
  if ( isEmpty() )
    return elemTriangle;
 
  QDomElement elemExterior = doc.createElementNS( ns, QStringLiteral( "exterior" ) );
  QDomElement curveElem = exteriorRing()->asGml3( doc, precision, ns, axisOrder );
  if ( curveElem.tagName() == QLatin1String( "LineString" ) )
  {
    curveElem.setTagName( QStringLiteral( "LinearRing" ) );
  }
  elemExterior.appendChild( curveElem );
  elemTriangle.appendChild( elemExterior );
 
  return elemTriangle;
}
 
QgsPolygon *QgsTriangle::surfaceToPolygon() const
{
  return toPolygon();
}
 
QgsCurvePolygon *QgsTriangle::toCurveType() const
{
  std::unique_ptr<QgsCurvePolygon> curvePolygon( new QgsCurvePolygon() );
  curvePolygon->setExteriorRing( mExteriorRing->clone() );
 
  return curvePolygon.release();
}
 
void QgsTriangle::addInteriorRing( QgsCurve *ring )
{
  delete ring;
}
 
bool QgsTriangle::deleteVertex( QgsVertexId position )
{
  Q_UNUSED( position )
  return false;
}
 
bool QgsTriangle::insertVertex( QgsVertexId position, const QgsPoint &vertex )
{
  Q_UNUSED( position )
  Q_UNUSED( vertex )
  return false;
}
 
bool QgsTriangle::moveVertex( QgsVertexId vId, const QgsPoint &newPos )
{
  if ( isEmpty() )
    return false;
 
  if ( !mExteriorRing || vId.part != 0 || vId.ring != 0 || vId.vertex < 0 || vId.vertex > 4 )
  {
    return false;
  }
 
  if ( vId.vertex == 4 )
  {
    vId.vertex = 0;
  }
 
  const int n = mExteriorRing->numPoints();
  const bool success = mExteriorRing->moveVertex( vId, newPos );
  if ( success )
  {
    // If first or last vertex is moved, also move the last/first vertex
    if ( vId.vertex == 0 )
      mExteriorRing->moveVertex( QgsVertexId( vId.part, vId.ring, n - 1 ), newPos );
    clearCache();
  }
  return success;
}
 
void QgsTriangle::setExteriorRing( QgsCurve *ring )
{
  if ( !ring )
  {
    return;
  }
 
  if ( ring->hasCurvedSegments() )
  {
    //need to segmentize ring as polygon does not support curves
    QgsCurve *line = ring->segmentize();
    delete ring;
    ring = line;
  }
 
  if ( ( ring->numPoints() > 4 ) || ( ring->numPoints() < 3 ) )
  {
    delete ring;
    return;
  }
  else if ( ring->numPoints() == 4 )
  {
    if ( !ring->isClosed() )
    {
      delete ring;
      return;
    }
  }
  else if ( ring->numPoints() == 3 )
  {
    if ( ring->isClosed() )
    {
      delete ring;
      return;
    }
    QgsLineString *lineString = static_cast< QgsLineString *>( ring );
    if ( !lineString->isClosed() )
    {
      lineString->close();
    }
    ring = lineString;
  }
 
  mExteriorRing.reset( ring );
 
  //set proper wkb type
  setZMTypeFromSubGeometry( ring, Qgis::WkbType::Triangle );
 
  clearCache();
}
 
QgsCurve *QgsTriangle::boundary() const
{
  if ( !mExteriorRing )
    return nullptr;
 
  return mExteriorRing->clone();
}
 
QgsPoint QgsTriangle::vertexAt( int atVertex ) const
{
  if ( isEmpty() )
    return QgsPoint();
 
  const QgsVertexId id( 0, 0, atVertex );
  return mExteriorRing->vertexAt( id );
}
 
QVector<double> QgsTriangle::lengths() const
{
  QVector<double> lengths;
  if ( isEmpty() )
    return lengths;
 
  lengths.append( vertexAt( 0 ).distance( vertexAt( 1 ) ) ); // c = |AB|
  lengths.append( vertexAt( 1 ).distance( vertexAt( 2 ) ) ); // a = |BC|
  lengths.append( vertexAt( 0 ).distance( vertexAt( 2 ) ) ); // b = |AC|
 
  return lengths;
}
 
QVector<double> QgsTriangle::angles() const
{
  QVector<double> angles;
  if ( isEmpty() )
    return angles;
 
  QVector<double> l = lengths();
 
  const double a = l[1];
  const double b = l[2];
  const double c = l[0];
 
  const double a2 = a * a;
  const double b2 = b * b;
  const double c2 = c * c;
 
  const double alpha = acos( ( b2 + c2 - a2 ) / ( 2 * b * c ) );
  const double beta = acos( ( a2 + c2 - b2 ) / ( 2 * a * c ) );
  const double gamma = M_PI - alpha - beta; // acos((a2 + b2 - c2)/(2*a*b)); but ensure that alpha+beta+gamma = 180.0
 
  angles.append( alpha );
  angles.append( beta );
  angles.append( gamma );
 
  return angles;
}
 
bool QgsTriangle::isDegenerate() const
{
  if ( isEmpty() )
    return true;
 
  const QgsPoint p1( vertexAt( 0 ) );
  const QgsPoint p2( vertexAt( 1 ) );
  const QgsPoint p3( vertexAt( 2 ) );
  return ( ( ( p1 == p2 ) || ( p1 == p3 ) || ( p2 == p3 ) ) || QgsGeometryUtils::leftOfLine( p1.x(), p1.y(), p2.x(), p2.y(), p3.x(), p3.y() ) == 0 );
}
 
bool QgsTriangle::isIsocele( double lengthTolerance ) const
{
  if ( isEmpty() )
    return false;
  const QVector<double> sides = lengths();
  const bool ab_bc = qgsDoubleNear( sides.at( 0 ), sides.at( 1 ), lengthTolerance );
  const bool bc_ca = qgsDoubleNear( sides.at( 1 ), sides.at( 2 ), lengthTolerance );
  const bool ca_ab = qgsDoubleNear( sides.at( 2 ), sides.at( 0 ), lengthTolerance );
 
  return ( ab_bc || bc_ca || ca_ab );
}
 
bool QgsTriangle::isEquilateral( double lengthTolerance ) const
{
  if ( isEmpty() )
    return false;
  const QVector<double> sides = lengths();
  const bool ab_bc = qgsDoubleNear( sides.at( 0 ), sides.at( 1 ), lengthTolerance );
  const bool bc_ca = qgsDoubleNear( sides.at( 1 ), sides.at( 2 ), lengthTolerance );
  const bool ca_ab = qgsDoubleNear( sides.at( 2 ), sides.at( 0 ), lengthTolerance );
 
  return ( ab_bc && bc_ca && ca_ab );
}
 
bool QgsTriangle::isRight( double angleTolerance ) const
{
  if ( isEmpty() )
    return false;
  QVector<double> a = angles();
  QVector<double>::iterator ita = a.begin();
  while ( ita != a.end() )
  {
    if ( qgsDoubleNear( *ita, M_PI_2, angleTolerance ) )
      return true;
    ++ita;
  }
  return false;
}
 
bool QgsTriangle::isScalene( double lengthTolerance ) const
{
  if ( isEmpty() )
    return false;
  return !isIsocele( lengthTolerance );
}
 
QVector<QgsLineString> QgsTriangle::altitudes() const
{
  QVector<QgsLineString> alt;
  if ( isEmpty() )
    return alt;
 
  alt.append( QgsGeometryUtils::perpendicularSegment( vertexAt( 0 ), vertexAt( 2 ), vertexAt( 1 ) ) );
  alt.append( QgsGeometryUtils::perpendicularSegment( vertexAt( 1 ), vertexAt( 0 ), vertexAt( 2 ) ) );
  alt.append( QgsGeometryUtils::perpendicularSegment( vertexAt( 2 ), vertexAt( 0 ), vertexAt( 1 ) ) );
 
  return alt;
}
 
QVector<QgsLineString> QgsTriangle::medians() const
{
  QVector<QgsLineString> med;
  if ( isEmpty() )
    return med;
 
  QgsLineString med1;
  QgsLineString med2;
  QgsLineString med3;
  med1.setPoints( QgsPointSequence() << vertexAt( 0 ) << QgsGeometryUtils::midpoint( vertexAt( 1 ), vertexAt( 2 ) ) );
  med2.setPoints( QgsPointSequence() << vertexAt( 1 ) << QgsGeometryUtils::midpoint( vertexAt( 0 ), vertexAt( 2 ) ) );
  med3.setPoints( QgsPointSequence() << vertexAt( 2 ) << QgsGeometryUtils::midpoint( vertexAt( 0 ), vertexAt( 1 ) ) );
  med.append( med1 );
  med.append( med2 );
  med.append( med3 );
 
  return med;
}
 
QVector<QgsLineString> QgsTriangle::bisectors( double lengthTolerance ) const
{
  QVector<QgsLineString> bis;
  if ( isEmpty() )
    return bis;
 
  QgsLineString bis1;
  QgsLineString bis2;
  QgsLineString bis3;
  const QgsPoint incenter = inscribedCenter();
  QgsPoint out;
  bool intersection = false;
 
  QgsGeometryUtils::segmentIntersection( vertexAt( 0 ), incenter, vertexAt( 1 ), vertexAt( 2 ), out, intersection, lengthTolerance );
  bis1.setPoints( QgsPointSequence() <<  vertexAt( 0 ) << out );
 
  QgsGeometryUtils::segmentIntersection( vertexAt( 1 ), incenter, vertexAt( 0 ), vertexAt( 2 ), out, intersection, lengthTolerance );
  bis2.setPoints( QgsPointSequence() <<  vertexAt( 1 ) << out );
 
  QgsGeometryUtils::segmentIntersection( vertexAt( 2 ), incenter, vertexAt( 0 ), vertexAt( 1 ), out, intersection, lengthTolerance );
  bis3.setPoints( QgsPointSequence() <<  vertexAt( 2 ) << out );
 
  bis.append( bis1 );
  bis.append( bis2 );
  bis.append( bis3 );
 
  return bis;
}
 
QgsTriangle QgsTriangle::medial() const
{
  if ( isEmpty() )
    return QgsTriangle();
  QgsPoint p1, p2, p3;
  p1 = QgsGeometryUtils::midpoint( vertexAt( 0 ), vertexAt( 1 ) );
  p2 = QgsGeometryUtils::midpoint( vertexAt( 1 ), vertexAt( 2 ) );
  p3 = QgsGeometryUtils::midpoint( vertexAt( 2 ), vertexAt( 0 ) );
  return QgsTriangle( p1, p2, p3 );
}
 
QgsPoint QgsTriangle::orthocenter( double lengthTolerance ) const
{
  if ( isEmpty() )
    return QgsPoint();
  const QVector<QgsLineString> alt = altitudes();
  QgsPoint ortho;
  bool intersection;
  QgsGeometryUtils::segmentIntersection( alt.at( 0 ).pointN( 0 ), alt.at( 0 ).pointN( 1 ), alt.at( 1 ).pointN( 0 ), alt.at( 1 ).pointN( 1 ), ortho, intersection, lengthTolerance );
 
  return ortho;
}
 
QgsPoint QgsTriangle::circumscribedCenter() const
{
  if ( isEmpty() )
    return QgsPoint();
  double r, x, y;
  QgsGeometryUtils::circleCenterRadius( vertexAt( 0 ), vertexAt( 1 ), vertexAt( 2 ), r, x, y );
  return QgsPoint( x, y );
}
 
double QgsTriangle::circumscribedRadius() const
{
  if ( isEmpty() )
    return 0.0;
  double r, x, y;
  QgsGeometryUtils::circleCenterRadius( vertexAt( 0 ), vertexAt( 1 ), vertexAt( 2 ), r, x, y );
  return r;
}
 
QgsCircle QgsTriangle::circumscribedCircle() const
{
  if ( isEmpty() )
    return QgsCircle();
  return QgsCircle( circumscribedCenter(), circumscribedRadius() );
}
 
QgsPoint QgsTriangle::inscribedCenter() const
{
  if ( isEmpty() )
    return QgsPoint();
 
  const QVector<double> l = lengths();
  const double x = ( l.at( 0 ) * vertexAt( 2 ).x() +
                     l.at( 1 ) * vertexAt( 0 ).x() +
                     l.at( 2 ) * vertexAt( 1 ).x() ) / perimeter();
  const double y = ( l.at( 0 ) * vertexAt( 2 ).y() +
                     l.at( 1 ) * vertexAt( 0 ).y() +
                     l.at( 2 ) * vertexAt( 1 ).y() ) / perimeter();
 
  QgsPoint center( x, y );
 
  QgsPointSequence points;
  points << vertexAt( 0 ) << vertexAt( 1 ) << vertexAt( 2 );
  QgsGeometryUtils::transferFirstZOrMValueToPoint( points, center );
 
  return center;
}
 
double QgsTriangle::inscribedRadius() const
{
  if ( isEmpty() )
    return 0.0;
  return ( 2.0 * area() / perimeter() );
}
 
QgsCircle QgsTriangle::inscribedCircle() const
{
  if ( isEmpty() )
    return QgsCircle();
  return QgsCircle( inscribedCenter(), inscribedRadius() );
}