3 IMPLEMENTATION DETAILS

Users of traditional ray tracers feel free to change the lighting and material parameters when the viewpoint is changed, and to add multiple lights to achieve a desired lighting effect. These are not practical in an interactive ray tracer where the lighting and material parameters are static as the viewpoint changes, and where even one light is expensive in terms of framerate. To help reduce the need for such traditional hacks, our implementation modifies the traditional key components of a ray tracer: lighting, material models, shadows, and ray-object intersection routines. In Section 3.1 we discuss how we handle and modify material models and lighting in a dynamic context. In Section 3.2 we discuss how we approximate soft shadows efficiently. In Section 3.3 we discuss how we compute ray-object intersections for spline surfaces.