TABLE OF CONTENTS Global illumination is all about generating paths connecting a virtual camera with a light source. In this appendix, we propose a library of software classes that will facilitate generating such paths in a computer program, by hiding the details of geometry and materials representation and ray casting from a higher-level algorithm implementation.
The library offers the following building blocks:
Classes for representing path nodes, such as a point on a light source, a surface scattering point, the viewing position, etc. (Section A.1).
Classes for light source sampling. These classes generate path nodes that serve as the head of light paths (Section A.2).
Support classes, representing a virtual screen buffer, classes for doing tone mapping, etc. (Section A.3).
The relationship between the classes is depicted in Figure A.1. Some example code fragments, illustrating the use of these classes, are presented in Section A.4.
The interface we describe here does not include a representation of geometry or materials itself. Such a representation is, of course, required in an actual implementation. Our implementation, on top of a VRML-based scene graph management library, is available from this book s website (http://www.advancedglobalillumination.com). In our experience, it is easy to port the class library to other global illumination platforms. Algorithms implemented on top of this interface may be portable to other global illumination systems supporting this interface almost without modifications. Our experiments have indicated that...
