double Vector3d::distance( Vector3d a, Vector3d b, Vector3d c ) {
// calculate 2 displacement vectors in plane
b.subtract( a );
c.subtract( a );
// calculate normal vector
Vector3d n = b.crossProduct( c );
Vector3d p = *this;
p.subtract( a );
return n.dotProduct( p ) / n.absoluteValue();
}
double Vector3d::distance( Vector3d v ) {
// calculate displacement vector
v.subtract( *this );
// return absolute value of displacement vector
return v.absoluteValue();
}