This article proposes and tests a two-component model for describing and programming the finegrained aspects of non-WIMP interaction. The model combines a data-flow or constraint-like component for the continuous relationships with an event-based component for discrete interactions, which can enable or disable individual continuous relationships. Its key ingredients are the separation of non-WIMP interaction into two components and the framework it provides for communication between the two

In this paper we introduce a discrete shell model describing the behavior of thin flexible structures whose rest configuration is nonflat. Previously such models required complex continuum mechanics formulations and correspondingly expensive algorithms. We show that a straightforward shell model can be derived in the discrete setting of triangle meshes and implemented through a simple modification to standard cloth simulation algorithms. The resulting technique convincingly simulates a variety of thin shell models ranging from cloth to thin metal like materials. We show the importance of non-flat rest configurations with a number of examples and demonstrate the quality of our results by comparing a simulation of a falling hat with real video footage.

We present a paradigm and toolkit for rapid prototyping of interactive, animated 3D graphics programs. The paradigm has its roots in declarative programming, emphasizing immutable values, first class functions, and relations, applying these concepts to a broad range of types, including points, vectors, planes, colors, transforms, geometry, and sound. The narrow role of modifiable state in this paradigm allows applications to be run in a collaborative setting (multi-user and multi-computer) without modification. CR Categories and Subject Descriptors: I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism; I.3.6 [Computer Graphics]: Methodology and Techniques; D.1.1 [Pro- gramming Techniques] Applicative (Functional) Programming; D.2.m [Software Engineering] Miscellaneous Rapid Prototyping; G.1.7 [Mathematics of Computing] Ordinary Differential Equations. Additional Keywords and Phrases: Local Propagation Constraints 1 Introduction TBAG is a paradigm and toolkit for ra...

Today's computer animators have access to many systems and techniques to author high quality motion. Unfortunately, available techniques typically produce a particular motion for a specific character. In this paper, we present a constraintbased approach to adapt previously created motions to new situations and characters. We combine constraint methods that compute changes to motion to meet specified needs, with motion-signal processing methods that modify signals yet preserve desired properties. This allows the adaptation of motions to meet new goals while retaining much of their original quality.

Introduction Today's user interfaces for most 3D graphics applications still depend heavily on 2D GUIs and keyboard input. There have been several recent attempts both to extend these user interfaces into 3D and to describe intermediary 3D widgets 1 that control application objects [3; 4; 5; 7; 13; 15]. Even though this style of interaction is a straightforward extension of interaction through intermediary 2D widgets such as dials or sliders, we know of no efforts to develop interactive 3D toolkits akin to UIMX or Garnet [11]. The Brown Graphics Group has had considerable experience using its Unified Graphics Architecture (UGA) system [16] to script 3D widgets such as deformation racks [14], interactive shadows [9], parameterized models, and other constrained 3D geometries. Using this experience, we have developed an interactive toolkit to facilitate the visual programming of the geometry and behavior of such interactive models. The toolkit provides both a co

In this paper, we present an expressive 3D animation environment that enables users to rapidly and visually prototype animated worlds with a fully 3D user-interface. A 3D device allows the specification of complex 3D motion, while virtual tools are visible mediators that live in the same 3D space as application objects and supply the interaction metaphors to control them. In our environment, there is no intrinsic difference between userinterface and application objects. Multi-way constraints provide the necessary tight coupling among components that makes it possible to seamlessly compose animated and interactive behaviors. By recording the effects of manipulations, all the expressive power of the 3D user interface is exploited to define animations. Effective editing of recorded manipulations is made possible by compacting all continuous parameter evolutions with an incremental data-reduction algorithm, designed to preserve both geometry and timing. The automatic generation of editable representations of interactive performances overcomes one of the major limitations of current performance animation systems. Novel interactive solutions to animation problems are made possible by the tight integration of all system components. In particular, animations can be synchronized by using constrained manipulation during playback. The accompanying video-tape illustrates our approach with interactive sequences showing the visual construction of 3D animated worlds. All the demonstrations in the video were recorded live and were not edited.

This paper describes the VB2 architecture for the construction of three-dimensional interactive applications. The system's state and behavior are uniformly represented as a network of interrelated objects. Dynamic components are modeled by active variables, while multi-way relations are modeled by hierarchical constraints. Daemons are used to sequence between system states in reaction to changes in variable values The constraint network is efficiently maintained by an incremental constraint solver based on an enhancement of SkyBlue. Multiple devices are used to interact with the synthetic world through the use of various interaction paradigms, including immersive environments with visual and audio feedback. Interaction techniques range from direct manipulation, to gestural input and threedimensional virtual tools. Adaptive pattern recognition is used to increase input device expressiveness by enhancing sensor data with classification information. Virtual tools, which are encapsulations...

This paper presents the architecture for an extensible toolkit used in construction and rapid prototyping of three dimensional interfaces, interactive illustrations, and three dimensional widgets. The toolkit provides methods for the direct manipulation of 3D primitives which can be linked together through a visual programming language to create complex constrained behavior. Features of the toolkit include the ability to visually build, encapsulate, and parameterize complex models, and impose limits on the models. The toolkit's constraint resolution technique is based on a dynamic object model similar to those in prototype delegation object systems. The toolkit has been used to rapidly prototype tools for mechanical modelling, scientific visualization, construct 3D widgets, and build mathematical illustrations. 3D Interface Toolkit April 21, 1994 3 1.0 Introduction There have been many advances in 2D user interface toolkits [8][10][11][12] which allow developers to rapidly prototyp...

An algebra consists of a set of objects and a set of operators that act on those objects. We treat shader programs as first-class objects and define two operators: connection and combination. Connection is functional composition: the outputs of one shader are fed into the inputs of another. Combination concatenates the input channels, output channels, and computations of two shaders. Similar operators can be used to manipulate streams and apply computational kernels expressed as shaders to streams. Connecting a shader program to a stream applies that program to all elements of the stream; combining streams concatenates the record definitions of those streams.

. While physically based approaches have been shown to be effective for creating graceful and realistic motions, keyframing systems are still the predominant tool for animation. This is due primarily to the control provided to the animator, as well as to the simple fast computation of in-between frames. In contrast, physical simulation systems automate the creation of realistic motion sequences, but remove most of the control from the animator. Recent work with spacetime constraints and optimal control has focused on balancing control and automation. However, either the algorithmic and computational complexity or the continuing lack of control have made it difficult to integrate these developments into real animation systems. The goal of the research reported here is to avoid disturbing the basic framework of keyframe systems while still offering many of the advantages of optimization based systems. We present an animation paradigm in which, as in keyframe systems, the user specifies a...