Open Inventor

Open Inventor

Open Inventor is an object-oriented toolkit that provides objects and methods for creating interactive 3D graphics applications. This toolkit contains 3D objects you can use to represent your 3D physical models, as well as objects that allow you to interactively operate on these models.

Figure 6-3 shows a single scene from a racing game created using Open Inventor. In this game, mouse buttons control the speed and position of a car as it moves along a track. Open Inventor creates scenes showing the car, the track, and the terrain that appears as the car moves along the track.

Figure 6-3 : A Scene Created by Open Inventor Open Inventor is written in C++ but also includes C bindings. It is object-oriented and extensible. The Inventor toolkit is based on OpenGL and provides a library of objects you can use, modify, and extend to meet your needs.

Figure 6-4 illustrates the architecture of an Open Inventor application. The Open Inventor components shown in the figure are described in the paragraphs following the figure.

Figure 6-4 : Open Inventor Architecture

Open Inventor Toolkit

The Open Inventor Toolkit provides three programming tools that you can use in your Open Inventor application.

Scene database: A scene database is a collection of 3D objects and properties arranged to represent a 3D scene. A scene is composed of nodes that define all information about an object--its shape, size, coloring, surface texture, and location in 3D space. You can use this information to render the object or to vary it in a variety of ways--for example, to move the object or change the way it looks. Some objects, called engines, are used to animate part of a scene.
Manipulators: A manipulator is a special kind of node that reacts to user events. Manipulator objects allow users to interact with 3D objects on a screen. Manipulators allow rendering into a scene and provide a means for translating user-initiated events into changes to the scene database.
Node kits: A node kit is a collection of nodes grouped together to provide a simplified model. Open Inventor provides these ready-made kits to make building a structured scene database easier. The kit provides the basic structure of an object, but allows you to define information specific to your object. For example, the shape node kit describes the shape but allows you to define a geometric specification, material, a lighting model, texture, and other properties of the shape.

Component Library

The Component Library is a convenience library for programmers who use X Window System and X-based toolkits such as Xt and Motif. It contains an event translator that converts X events into Open Inventor events.

3D Interchange File Format

Open Inventor includes an interchange file format for exchanging 3D objects and scenes between applications. Objects in the scene database can be written to a file during the execution of your program, in either ASCII or binary form.