英文原文 Extending Blender: Development of a Haptic Authoring ToolAbstract -In this paper, we present our work to extend a well known 3D graphic modeler -Blender -to support haptic modeling and rendering. The extension tool is named HAMLAT (haptic Application Markup Language Authoring Tool). We describe the modifications and additions to the Blender source code which have been used to create HAMLAT Furthermore, we present and discuss the design decisions used when developing HAMLAT, and also an implementation road map which describes the changes to the Blender source code. Finally, we conclude with discussion of our future development and research avenues. Keywords -Haptics, HAML, Graphic Modelers, Blender, Virtual Environments. I. Introduction A. Motivation The increasing adoption of haptic modality in human-computer interaction paradigms has led to a huge demand for new tools that help novice users to author and edit haptic applications. Currently, the haptic application development process is a time consuming experience that requires programming expertise. The complexity of haptic applications development rises from the fact that the haptic application components (such as the haptic API, the device, the haptic rendering algorithms, etc.) need to interact with the graphic components in order to achieve synchronicity. Additionally, there is a lack of application portability as the application is tightly coupled to a specific device that necessitates the use of its corresponding API. Therefore, device and API heterogeneity lead to the fragmentation and disorientation of both researchers and developers. In view of all these considerations, there is a clear need for an authoring tool that can build haptic applications while hiding programming details from the application modeler (such as API, device, or virtual model). This paper describes the technical development of the haptic Application Markup Language Authoring Tool (HAMLAT). It is intended to explain the design decisions used for developing HAMLAT and also provides an implementation road map, describing the source code of the project. B. Blender HAMLAT is based on the blender 1 software suite, which is an open-source 3D modeling package with a rich feature set. It has a sophisticated user interface which is noted for its efficiency and flexibility, as well as its supports for multiple file formats, physics engine, modem computer graphic rendeing and many other features. Because of blenders open architecture and supportive community base, it was selected as the platform of choice for development of HAMLAT. The open-source nature of Blender means HAMLAT can easily leverage its existing functionality and focus on integrating haptic features which make it a complete hap to-visual modeling tool, since developing a 3D modeling platform from scratch requires considerable development time and expertise in order to reach the level of functionality of blender. Also, we can take advantage of future improvements to blender by merging changes from its source code into the HAMLAT source tree. HAMLAT builds on existing Blender components, such as the user-interface and editing tools, by adding new components which focus on the representation, modification, and rendering of haptic properties of objects in a 3D scene. By using Blender as the basis for HAMLAT, we hope to develop a 3D haptic modeling tool which has the maturity and features of Blender combined with the novelty of haptic rendering. C. Project Goals As previously stated, the overall goal for the HAMLAT project is to produce a polished software application which combines the features of a modem graphic modeling tool with haptic rendering techniques. HAMLAT has the look and feel of a 3D graphical modeling package, but with the addition of features such as haptic rendering and haptic property descriptors. This allows artists, modelers, and developers to generate realistic 3D hapto-visual virtual environments. A high-level block diagram of HAMLAT is shown in Figure 1. It illustrates the flow of data in the haptic modeling. HAMLAT assists the modeler, or application developer, in building hap to-visual applications which may be stored in a database for later retrieval by another haptic application. By hapto-visual application we refer to any software which displays a 3D scene both visually and haptically to a user in a virtual setting. An XML file format, called HAML 2, is used to describe the 3D scenes and store the hapto-visual environments built by a modeler for later playback to an end user. Traditionally, building hapto-visual environments has required a strong technical and programming background. The task of haptically rendering a 3D scene is tedious since haptic properties must be assigned to individual objects in the scene and currently there are few high-level tools for accomplishing thi