示例#1
0
//
//#############################################################################
//#############################################################################
//
Scalar
	Stuff::Find_Closest_Approach(
		const Point3D& origin1,
		const Vector3D& velocity1,
		Point3D *result1,
		const Point3D& origin2,
		const Vector3D& velocity2,
		Point3D *result2,
		Scalar *time,
		bool *constant
	)
{
	Vector3D a,b;
	a.Subtract(origin1, origin2);
	b.Subtract(velocity1, velocity2);

	//
	//--------------------------------------------------------------------
	// If the velocities are identical, any point will do for the test, so
	// simply return the difference between the starting points
	//--------------------------------------------------------------------
	//
	Scalar d = b.GetLengthSquared();
	if (Small_Enough(d))
	{
		*constant = true;
		d = a.GetLength();
		return d;
	}

	//
	//-------------------------------------------------------------------------
	// The velocities are not parallel, so figure out when the closest approach
	// is via the derivative
	//-------------------------------------------------------------------------
	//	
	*constant = false;
	*time = (a * b) / -d;

	//
	//------------------------------------------------------
	// Now, plot the resultant points of both line equations
	//------------------------------------------------------
	//
	Vector3D closest;
	closest.AddScaled(a, b, *time);
	result1->AddScaled(origin1, velocity1, *time);
	result2->AddScaled(origin2, velocity2, *time);
	d = closest.GetLength();
	return d;
}