Screen to world point with oblique camera

gistfile1.txt

Vector2 mousePos = Input.mousePosition;
		if (lastMousePos.Equals(mousePos)) {
			return;
		}
		lastMousePos = mousePos;
		Ray ray = Camera.main.ScreenPointToRay(mousePos);
		float dist;
		Plane plane = new Plane(Vector3.up, Vector3.right, Vector3.down);
		plane.Raycast(ray, out dist);
		Vector3 worldPoint = Camera.main.ScreenToWorldPoint(new Vector3(mousePos.x, mousePos.y, dist));