To make computer programs more comprehensible, the presentation of program source text, program documentation, and program execution needs to be enhanced. A number of techniques and tools developed to achieve these en...
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ISBN:
(纸本)0897912586
To make computer programs more comprehensible, the presentation of program source text, program documentation, and program execution needs to be enhanced. A number of techniques and tools developed to achieve these ends are described. One of these is a design for the effective presentation of source text in the C programming language using high-quality digital typography;a processor which implements the design is also given. Some experimental evidence is summarized to demonstrate that the resulting source text presentation is significantly more readable and comprehensible than the presentation conventionally used today. Brief descriptions are given of two other techniques, the development of a system of structured program documentation incorporating both text and graphics and the portrayal of program execution with colored computer animation.
Two experiments investigated various techniques for displaying the evaluation of LISP functions in an interactive dcbugger. The studies examined three techniques of highlighting the flow of evaluation in a LISP functi...
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ISBN:
(纸本)0201142376
Two experiments investigated various techniques for displaying the evaluation of LISP functions in an interactive dcbugger. The studies examined three techniques of highlighting the flow of evaluation in a LISP function and two display formats for displaying LISP function information. The subjects in both experiments included highly experienced LISP programmers and occasional LISP users with moderate to little LISP experience. The dependent measure was the subjects' preference rating for each display technique. The results showed that occasional LISP users preferred range highlighting, an interlaced display of evaluation results, and a simultaneous display of called functions. However, expert LISP programmers had no differential preferences for highlighting techniques.
This paper describes and evaluates the design of four virtual controllers for use in rotating three-dimensional objects using the mouse. Three of four of these controllers are 'new' in that they extend traditi...
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This paper describes and evaluates the design of four virtual controllers for use in rotating three-dimensional objects using the mouse. Three of four of these controllers are 'new' in that they extend traditional direct manipulation techniques to a 3-D environment. User performance is compared during simple and complex rotation tasks. The results indicate faster performance for complex rotations using the new continuous axes controllers compared to more traditional slider approaches. No significant differences in accuracy for complex rotations were found across the virtual controllers. A second study compared the best of these four virtual controllers (the Virtual Sphere) to a control device by Evans, Tanner and Wein. No significant differences either in time to complete rotation task or accuracy of performance were found. All but one subject indicated they preferred the virtual sphere because it seemed more 'natural'.
When several objects are moved about by computer animation, there is the chance that they will interpenetrate. This is often an undesired state, particularly if the animation is seeking to model a realistic world. Two...
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ISBN:
(纸本)9780897912754
When several objects are moved about by computer animation, there is the chance that they will interpenetrate. This is often an undesired state, particularly if the animation is seeking to model a realistic world. Two issues are involved: detecting that a collision has occurred, and responding to it. The former is fundamentally a kinematic problem, involving the positional relationship of objects in the world. The latter is a dynamic problem, in that it involves predicting behavior according to physical laws. This paper discusses collision detection and response in general, presents two collision detection algorithms, describes modeling collisions of arbitrary bodies using springs, and presents an analytical collision response algorithm for articulated rigid bodies that conserves linear and angular momentum.
The roster model is an array-theoretic alternative to the set-theoretic relational model for handling tabular data. The roster model and its operations are extended here to incorporate fuzzy data modeling and manipula...
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ISBN:
(纸本)0818608439
The roster model is an array-theoretic alternative to the set-theoretic relational model for handling tabular data. The roster model and its operations are extended here to incorporate fuzzy data modeling and manipulation using possibility theory. The results is a fuzzy roster model, in which two levels of uncertainty are represented: the uncertainty in the data itself and the uncertainty in the truth value of the data. Fuzzy projections, selections, and joinings in the model are illustrated with the use of examples. The original roster model and the fuzzy roster model are implemented in the Nested interactive Array Language (NIAL) and are running on a Unix-based SUN-3 Workstation.
A parallel algorithm for the rasterization of polygons is presented that is suited for 3D Z-buffered graphics implementations. The algorithm represents each edge of a polygon by a linear edge function that has a value...
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A parallel algorithm for the rasterization of polygons is presented that is suited for 3D Z-buffered graphics implementations. The algorithm represents each edge of a polygon by a linear edge function that has a value greater than zero on one side of the edge and less than zero on the opposite side. The value of the function can be interpolated with hardware similar to hardware required to interpolate color and Z pixel values. The edge function of adjacent pixels may be easily computed in parallel. The coefficients of the 'Edge function' can be computed from floating point endpoints in such a way that sub-pixel precision of the endpoints can be retained.
The theory and implementation for a computer animation system to model a general class of three dimensional dynamic processes for arbitrary rigid bodies is presented. The simulation of the dynamic interaction among ri...
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The theory and implementation for a computer animation system to model a general class of three dimensional dynamic processes for arbitrary rigid bodies is presented. The simulation of the dynamic interaction among rigid bodies takes into account various physical characteristics such as elasticity, friction, mass, and moment of inertia to produce rolling and sliding contacts. If a set of bodies is statically unstable, the system dynamically drives it toward a stable configuration while obeying the geometric constraints of the system including general non-holonomic constraints. The system provides a physical environment with which objects animated using more traditional techniques can interact. The degree of interaction is controlled by the animator. A computationally efficient method to merge kinematics and dynamics for articulated rigid bodies to produce realistic motion is presented.
This paper presents rendering techniques that use volumes as the basic geometric primitives. It defines data structures composed of numerous subvolumes, in excess of 100,000. Over each subvolume, a scalar field descri...
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This paper presents rendering techniques that use volumes as the basic geometric primitives. It defines data structures composed of numerous subvolumes, in excess of 100,000. Over each subvolume, a scalar field describes the variation of some physical quantity. The two rendering methods described assume a trilinear variation of this scalar field within each volume element, unlike voxel-based techniques that assume a constant value for each subvolume. The result is a higher order approximation of the structures within the volume. Solid texture mapping, atmospheric attenuation, and transfer functions relating the dynamic range of the scalar field to color and opacity are used to isolate important data features. The result is a new method for the visualization of three-dimensional data resulting from numerical simulations and observations of natural phenomena. This method continuously covers the gap between surface-based and voxel-based techniques.
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