Third Person Camera System

void Camera::UpdatePosition(const Vector3 &vTargetPosition, const Vector3 &vTargetOrientation, float dt){	// Get the amount of rotation of the target as radians (rather than a vector).	float fAngle = VectorAngle2v(vTargetOrientation, Vector3(0.0f, 0.0f, 1.0f));		// Adjust the desired camera rotation, accounting for the targets rotation.	fAngle -= mfAzimuth;	// Calculate the "desired" camera position. This is the position that the	// camera would be in if it's weren't constrained by the spring system. The	// spring system controls the camera motion towards this "desired" point.	Vector3 vDesiredPosition;	vDesiredPosition.x = mfDistance * sinf(fAngle) * sinf(mfAltitude + kHalfPi) + vTargetPosition.x;	vDesiredPosition.y = mfDistance * cosf(mfAltitude + kHalfPi) + vTargetPosition.y;	vDesiredPosition.z = mfDistance * cosf(fAngle) * sinf(mfAltitude + kHalfPi) + vTargetPosition.z;	// The camera shouldn't move too quickly, so we need to get it to slowly	// approach the "desired" camera position. This is achieved by moving the	// camera a fixed percentage towards the desired camera position. The 	// greater the distance between the current camera position and the 	// desired camera position, the faster the camera moves.	Vector3 vMovementDirection = vDesiredPosition - mvPosition;	float fLength = vMovementDirection.Length();	float fDistanceToMove = mfTightness * (fLength * dt);	vMovementDirection.Normalise();	// No we simply move the camera along our movement vector (vMovementDirection)	// by the specified amount (fDistanceToMove). This places the camera at its	// new position.	mvPosition += vMovementDirection * fDistanceToMove;	mvView = vTargetPosition;	// We want to look at our target.	// Recalculate the facing/cross vectors that are used for controlling the	// avatar movement.	mvFacing = mvView - mvPosition;	mvFacing.Normalise();	mvCross = Vector3(mvFacing.z, 0.0f, -mvFacing.x);	mvUp = Cross(mvFacing, mvCross);	mvUp.Normalise();}