I have implemented an orbit camera and it seems to work but there is a strange twitch that happens when I rotate around the Y-axis too fast. I have recorded and posted it to youtube for your viewing pleasure :). If I move slowly it seems okay, but if I move the mouse quickly right/left, the entire scene becomes kind of skewed. The problem is most prominent in the angle recorded on the video and does not happen if the camera direction is parallel with the floor. I am not sure what could be causing it.

The camera code:

void CameraControl::Update(Camera *camera, UserInput *input)
{
	// Rotation
        // position and previousPosition are the positions of the mouse
	float yaw = (input->position.x - input->previousPosition.x) * -0.005f;
	float pitch = (input->position.y - input->previousPosition.y) * -0.005f;

	Vector3 targetToCameraVector = camera->position - camera->target;
	float length = Math::Length(targetToCameraVector);

	targetToCameraVector = Math::Normalize(targetToCameraVector);

	Vector3 forward = -targetToCameraVector;
	Vector3 right = Math::CrossProduct(forward, Vector3(0, 1, 0));
	right = Math::Normalize(right);
	Vector3 up = Math::CrossProduct(right, forward);
	up = Math::Normalize(up);

	Vector4 rotatedTargetToCameraVector = Math::GetRotation(pitch, right) *
		Math::GetRotation(yaw, Vector3(0, 1, 0)) * Vector4(targetToCameraVector, 0.0f);

	camera->position = camera->target + Math::Normalize(Vector3(rotatedTargetToCameraVector)) * length;

	camera->viewMatrix = Math::LookAt(camera->position, camera->target, up);
}

I would welcome any suggestions. Thanks.

Thanks for your help guys. Nypyren you were exactly right, recalculating the up vector solved the problem. If I could have a couple more questions:

The code now looks like this:

	// Rotation velocity
	float decceleration = 0.9f;
	float rotationSpeed = 0.0007f;
	static float yaw = 0.0f;
	static float pitch = 0.0f;
	yaw = yaw * decceleration + (input->position.x - input->previousPosition.x) * -rotationSpeed;
	pitch = pitch * decceleration + (input->position.y - input->previousPosition.y) * -rotationSpeed;

	// Rotation
	Vector3 targetToCameraVector = camera->position - camera->target;
	float cameraDistance = Math::Length(targetToCameraVector);
	
	targetToCameraVector = Math::Normalize(targetToCameraVector);

	Vector3 forward = -targetToCameraVector;
	Vector3 right = Math::CrossProduct(forward, Vector3(0, 1, 0));
	right = Math::Normalize(right);
	Vector3 up = Math::CrossProduct(right, forward);
	up = Math::Normalize(up);

	Vector3 oldPosition = camera->position;
	
	Vector4 rotatedTargetToCameraVector = Math::GetRotation(pitch, right) *
		Math::GetRotation(yaw, Vector3(0, 1, 0)) * Vector4(targetToCameraVector, 0.0f);

	camera->position = camera->target + Math::Normalize(Vector3(rotatedTargetToCameraVector)) * cameraDistance;

	// Recalculate up for the View Matrix
	forward = camera->target - camera->position;
	right = Math::CrossProduct(forward, Vector3(0, 1, 0));
	right = Math::Normalize(right);
	up = Math::CrossProduct(right, forward);
	up = Math::Normalize(up);

	// Check whether the camera is going to get parallel with the (0, 1, 0) vector
	// (either looking straight up or down) if so, send it the other way
	if (Math::Dot(-Math::Normalize(forward), Vector3(0, 1, 0)) > 0.95f)
	{
		yaw = 0.0f;
		pitch = 0.08f;
	}
	else if (Math::Dot(-Math::Normalize(forward), Vector3(0, -1, 0)) > 0.95f)
	{
		yaw = 0.0f;
		pitch = -0.08f;
	}

1. Is there a smarter way of calculating the forward, up and right vectors? It seems ike I am currently it doing it twice, although it also looks like it is unavoidable (at least the way my code is set up currently).

2. If the camera tries to look at the object from straight up or down, the rotation pushes it over the edge and the scene gets flipped. I tried to counter that by setting a limit on how parallel with the (0, 1, 0) vector the camera direction ray can get and if it that boundary is passed, the rotation is reversed. But it has the side effect that you cannot look straight down at the object and I don't like that. Is there an obvious solution to this problem?

Thanks.

All right, thanks for the suggestion I will definitely look into that.