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# Finding where vectors intersect

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Hi. I am trying to program realistic car physics for a go cart game that I am writing. I am following the car physics tutorial in the resources area of this site. When turning you need to find the circle created by the front wheels and back wheels. I have the right vector of the front wheels and that of the back wheels. When the front wheel is tryned to the right, these should intersect. How do I find out where they intersect, so that I can get the redius of this circle. Thanks Giant

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  class Line{public:	// Line equation: L = m_M * t + m_B	Vector3	m_M;	///< Direction (length is always 1)	Vector3	m_B;	///< Location of a point on the line};int Intersection( Line const & a, Line const & b, float * pt, float * pu ){	Vector3 const	n	= Cross( a.m_M, b.m_M );	Vector3 const	ab	= b.m_B - a.m_B;		// If the lines are parallel, then there are either 0 or infinite intersections ...	if ( Math::IsCloseToZero( n.Length2(), 2.*Math::DEFAULT_FLOAT_TOLERANCE ) )	{		float const	d	= Dot( ab, a.m_M );		if ( Math::IsRelativelyCloseTo( ab.Length2(), d * d, 2.*Math::DEFAULT_FLOAT_TOLERANCE ) )		{			return std::numeric_limits<int>::max();	// Co-linear, return big number		}		else		{			return 0;	// No intersection, return 0		}	}	// ... they are not parallel but if the distance between them is > 0 ...	else if ( !Math::IsCloseToZero( Dot( n, ab ) ) )	{		return 0;	// No intersection, return 0	}	// ... otherwise, they intersect at a single point ...	else	{		// Source: http://www.flipcode.com/geometry/gprimer2_issue02.shtml		// Use the minor with largest determinant to maintain precision and prevent divide-by-0		if ( fabs( n.m_Z ) > fabs( n.m_X )  &&  fabs( n.m_Z ) > fabs( n.m_Y ) )		{			*pt =   ( ab.m_X * b.m_M.m_Y - ab.m_Y * b.m_M.m_X ) / n.m_Z;			*pu = - ( ab.m_X * a.m_M.m_Y - ab.m_Y * a.m_M.m_X ) / n.m_Z;		}		else if ( fabs( n.m_X ) > fabs( n.m_Y ) )		{			*pt =   ( ab.m_Y * b.m_M.m_Z - ab.m_Z * b.m_M.m_Y ) / n.m_X;			*pu = - ( ab.m_Y * a.m_M.m_Z - ab.m_Z * a.m_M.m_Y ) / n.m_X;		}		else		{			*pt =   ( ab.m_Z * b.m_M.m_X - ab.m_X * b.m_M.m_Z ) / n.m_Y;			*pu = - ( ab.m_Z * a.m_M.m_X - ab.m_X * a.m_M.m_Z ) / n.m_Y;		}		return 1;	// 1 intersection, return 1	}}int Intersection( Line const & a, Line const & b, Point * pi ){	float		t, u;	int const	n		= Intersection( a, b, &t, &u );		if ( n == 1 )	{		*pi = a.m_M * t + a.m_B;	}			return n;}

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