Ejemplo n.º 1
0
bool QgsRay2D::intersects( const QgsLineSegment2D &segment, QgsPointXY &intersectPoint ) const
{
  const QgsVector ao = origin - segment.start();
  const QgsVector ab = segment.end() - segment.start();
  const double det = ab.crossProduct( direction );
  if ( qgsDoubleNear( det, 0.0 ) )
  {
    const int abo = segment.pointLeftOfLine( origin );
    if ( abo != 0 )
    {
      return false;
    }
    else
    {
      const double distA = ao * direction;
      const double distB = ( origin - segment.end() ) * direction;

      if ( distA > 0 && distB > 0 )
      {
        return false;
      }
      else
      {
        if ( ( distA > 0 ) != ( distB > 0 ) )
          intersectPoint = origin;
        else if ( distA > distB ) // at this point, both distances are negative
          intersectPoint = segment.start(); // hence the nearest point is A
        else
          intersectPoint = segment.end();
        return true;
      }
    }
  }
  else
  {
    const double u = ao.crossProduct( direction ) / det;
    if ( u < 0.0 || 1.0 < u )
    {
      return false;
    }
    else
    {
      const double t = -ab.crossProduct( ao ) / det;
      intersectPoint = origin + direction * t;
      return qgsDoubleNear( t, 0.0 ) || t > 0;
    }
  }
}
Ejemplo n.º 2
0
bool QgsClockwiseAngleComparer::operator()( const QgsPointXY &a, const QgsPointXY &b ) const
{
  const bool aIsLeft = a.x() < mVertex.x();
  const bool bIsLeft = b.x() < mVertex.x();
  if ( aIsLeft != bIsLeft )
    return bIsLeft;

  if ( qgsDoubleNear( a.x(), mVertex.x() ) && qgsDoubleNear( b.x(), mVertex.x() ) )
  {
    if ( a.y() >= mVertex.y() || b.y() >= mVertex.y() )
    {
      return b.y() < a.y();
    }
    else
    {
      return a.y() < b.y();
    }
  }
  else
  {
    const QgsVector oa = a - mVertex;
    const QgsVector ob = b - mVertex;
    const double det = oa.crossProduct( ob );
    if ( qgsDoubleNear( det, 0.0 ) )
    {
      return oa.lengthSquared() < ob.lengthSquared();
    }
    else
    {
      return det < 0;
    }
  }
}