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;
}
}
}
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;
}
}
}
