| 摘要 |
A trackball rotates a three-dimensional image displayed by a computer. Displacement data is generated for designated first and second non-antipodal points on the surface of the trackball's roller ball, for displacement of the designated first and second points during a time interval between a starting time and an ending time. The displacement data is used to generate a rotational transformation that is representative of a change in rotational orientation of the roller ball occurring during the time interval. The generated transformation is then applied to the displayed computer image to cause the image to be rotated around an image pivot point in correspondence with the rotation of the roller ball around its center.
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