Physically-based modeling has been used in the past to support a variety of interactive modeling tasks including free-form surface design, mechanism design, constrained drawing, and interactive camera control. In these systems, the user interacts with the model by exerting virtual forces, to which the system responds subject to the active constraints. In the past, this kind of interaction has been applicable only to models that are governed by continuous parameters. In this paper we present an extension to mixed continuous /discrete models, emphasizing constrained layout problems that arise in architecture and other domains. When the object being dragged is blocked from further motion by geometric constraints, a local discrete search is triggered, during which transformations such as swapping of adjacent objects may be performed. The result of the search is a "nearby" state in which the target object has been moved in the indicated direction and in which all constraints are satisfied. ...

Use of constraint-based techniques in interactive graphics applications poses a variety of unique challenges to system implementors. This paper begins by describing how interface concerns create demands on interactive, constraint-based, graphical applications. We will discuss why such applications must be able to handle systems of non-linear constraints, and survey some of the techniques available to solve them. Employing these numerical algorithms in the contexts of interactive systems provides a set of challenges, including dynamically setting up the equations to be solved and achieving adequate performance and scalability. This paper will explore these issues and describe the methods we have used in our efforts to address them. 1

Highly interactive Web-based courseware allows for a more intuitive learning than nowadays textbooks. A high level of interaction and cooperation is crucial for the success in stirring up the participants' emotions and involving him into self-acting studies. The basic requirements for the underlying programming architecture are interdisciplinary. We describe a general framework for rapid development and easy enhancement of Web-based courseware with special focus on concepts that meet the task of providing scripting and cooperation for highly interactive content.

Scheduling, routing, and layout tasks are examples of hard operations-research problems that have broad application in industry. Typical algorithms for these problems combine some form of gradient descent to find local minima with some strategy for escaping nonoptimal local minima. Our idea is to divide these two subtasks cleanly between human and computer: in our paradigm of human-guided simple search the computer is responsible only for finding local minima using a simple hill-climbing search; using visualization and interaction techniques, the human user identifies promising regions of the search space for the computer to explore, and intervenes to help it escape nonoptimal local minima. We have applied our approach to the problem of capacitated vehicle routing with time windows, a commercially important problem with a rich research history. Despite its simplicity, our prototype system is competitive with the majority of previously reported systems on benchmark academic p...

We investigate the usability of constraint-based alignment and distribution placement tools in diagram editors. Currently one-way constraints are used to provide alignment and distribution tools in many commercial editors. We believe the limitations of these constraints lead to serious usability issues, and thus suggest that such tools be implemented using multi-way constraints. We have conducted two usability studies, the first studies we are aware of that examine the relative usefulness of interactive graphical tools based on one-way and multi-way constraints. They provide strong evidence that multi-way constraint-based alignment and distribution tools are more usable than one-way constraint-based alignment and distribution tools.

CMon is a general-purpose performance monitoring system. It enables monitoring of long-running programs in a setting where the experimenters who are interested in the performance data are different from the users who run the programs that generate the data. Among other things, this permits programs to be monitored under real workload conditions. PSpec is a language and set of tools for performance assertion checking,an approach to automating the testing of performance properties of complex systems. It can be used in conjunction with the CMon system to produce a performance monitor that runs continuously, over the lifetime of a program, and automatically detects performance anomalies. In this report we describe the design and implementation of CMon and the continuous monitoring features of PSpec, and report on our experience using the systems. Contents 1 Introduction 1 2 Continuous Monitoring 2 2.1 Design................................ 3 2.2 ImplementationIssues ....................

this paper we describe a system to show some limited effects on a static toy-car model and present techniques that can be used in similar setups. Our focus is on creating apparent motion for animation