Orientation calculation apparatus, storage medium having orientation calculation program stored therein, game apparatus, and storage medium having game program stored therein

摘要

An orientation calculation apparatus obtains data from an input device including at least a gyroscope and an acceleration sensor, and calculates an orientation of the input device in a three-dimensional space. Orientation calculation means calculates the orientation of the input device in accordance with an angular rate detected by the gyroscope. Acceleration vector calculation means calculates an acceleration vector representing an acceleration of the input device in accordance with acceleration data from the acceleration sensor. Correction means corrects the orientation of the input device such that a direction of the acceleration vector in the space approaches a vertically downward direction in the space. Also, the correction means corrects the orientation of the input device such that a directional change before and after the correction is minimized regarding a predetermined axis representing the orientation of the input device.