Kenneth B. Evans

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The ability of the user of a graphics system to interactively control the motions of 3-D objects enhances his or her spatial perception and comprehension of those objects. This paper describes several logical devices based on the tablet, each particularly suited to control some type of interactive manipulation of 2-D and 3-D objects in real time. The(More)
Purpose: To scale objects independently along x-and y-axes, about a user-specified center of scaling [1]. Description : The rack is a modification of the two-axis trackball or the two-axis number wheel [2], and is designed to facilitate the scaling or stretching of objects. First the center of origin of the scaling operation must be determined, and then the(More)
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