| 摘要 |
In response to user signals requesting motion of a displayed object, a system presents a sequence of images, each including an object perceptible as a moved continuation of the previously displayed object. The user can independently request radial motion and lateral motion, and the system presents a sequence of images in which the object is displaced radially by the requested radial motion and laterally by the requested lateral motion. The user can request lateral motion by operating a mouse and can request radial motion by operating keys on a keyboard, with one key requesting motion toward a radial source and another key requesting motion away from the radial source. The radial source can be the viewpoint. The object's motion toward the viewpoint includes two phases. In the first phase, the object follows an acceleration path, enabling the user to control motion near its starting point and providing increasingly rapid motion; in the second phase, it follows an asymptotic path, enabling the user to control its motion as it approaches the viewpoint and preventing it from passing the viewpoint. The displacements between positions on the asymptotic path can follow a logarithmic function, with each displacement a proportion of the distance from the previous position to the viewpoint. The phases can be produced by using the logarithmic function to clip an acceleration function. The same rate of acceleration can be applied when the user requests motion away from the viewpoint. The processor can perform an animation loop.
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