Existing graphics systems are too large for students to study in an introductory computer graphics course. We have implemented a lightweight, object-oriented graphics system called OGS for instruction. OGS is written in Java. It demonstrates how a graphics system is implemented from scratch and is intended to help students understand graphics algorithms at the source code level. OGS implements window-viewport coordinate transformation, projection, 3D transformation, hidden surface elimination, Lambert shading, Phong hading, Constructive Solid Geometry, and ray tracing. OGS is able to model specular highlight, shadow, reflection and transmission.Keywords and Phases: OGS, computer graphics, polygon mesh, ray tracin
