Act: an easy-to-use and dynamically extensible 3D graphics library

Waldemar Celes
Jonathan Corson-Rikert

Program of Computer Graphics, Cornell University

Abstract. This paper presents Act, an object-oriented library for projects from specialized 3D graphics applications to simple interactive educational programs. Act meets the needs of both occasional and expert graphics programmers, offering a high-level access to the OpenGL(tm) library and additional features including object creation, manipulation, and interaction. An interpreted language allows the Act library to be extended easily and dynamically.

Examples

Two simple applications may illustrate the use of Act. Both applications were coded entirely in Lua.

Solar System

For educational purpose, we developed an animated model of the solar system with its planets and major moons. The image on the side shows the application screen. The user can control the scale the planets are drawn and can also control the simulation speed. A short MPEG movie shows some navegations in the solar system. The movie has 4 fragments. First, it illustrates a few planets and their orbits about the sun. Then it shows a close view of the earth and its moon. The third fragment shows how the sky is looked from a point on the surface of the earth. Finally, it shows a journey from pluto toward the sun.

3D Modeler

We created a 3D modeler to illustrate the use of Act. The image on the side shows the modeler screen. The program allows the user to interatively create primitive shapes with a color or pre-defined texture, translate and rotate shapes, and undo or redo any action. A short MPEG movie illustrates the use of the modeler.