ShadowGui – An Interactive Shadow Tutorial

Abstract

Today's mainstream computer graphics converges more and more to what was, in the past, possible only to do with expensive workstations. The addition of shaders to consumer graphic boards, which enable the usage of special effects like bump mapping and per pixel lighting, changed the look of today's computer graphics totally. One main effect, which makes the scene look more realistic, is shadows. It can help the viewer to understand the relative position of objects making the scene more believable. There are several common methods of making shadows, each of them having advantages and disadvantages. The two most popular methods are shadow mapping and stencil shadow volumes. In this tutorial, both shadow methods are explained two times. The first time, using only pure cpu-power, which makes the approaches slow, but they are easier to understand. Then, the tutorial explains how to use the power of today's graphic cards by outsourcing calculations to shaders. Because the shadow generation methods are implemented using OpenGL, previous knowledge about this graphics library is recommended, for example how to move objects by manipulating the glModelView matrix. However, all that must be known to calculate shadows will be explained in this tutorial.