General Note: If you need to use globals: feel free. There are some things that you probably can't even do without use of globals here since you don't control the flow of control.

BSpline Clarification: For the B-Splines, fix t at 1 (so that the Bspline matrix you are going to use is the same as the one appearing in the book on page 341 at the top).
Also: as noted in the handout, you have to draw a spline for every consecutive 4 points you have. If you have less than 4 points, you don't have to draw anything.

Ray Tracing Clarification: You don't have to toil too hard on constructing the room for the ray tracing. Make it easy on you, with little variation.