1. A computer-implemented method of managing secondary rays in a ray-tracing process, the computer-implemented method comprising: defining and constructing a unidirectional ray tracing object, wherein the unidirectional ray tracing object prevents secondary tracing rays from emanating from a user-selected virtual object in a computer generated illustration; logically surrounding the user-selected virtual object with the unidirectional ray tracing object; and ray tracing virtual secondary rays in the computer generated illustration, wherein the unidirectional ray tracing object prevents secondary rays from emanating from the user-selected virtual object.