Bidirectional Path Tracing using Nvidia Optix , Part 4 (Multiple lights and some bug fixes)

Hello again,

This time I have very little stuff to show couple of bugs , several performance issues and multiple lights :

With the help from the nvidia developers forum i corrected a bug in my random generator. I passed my random generator "seed" from hop to hop in the path by value, whereas by reference was the best solution to update the seed variable.

On top of that I have made several performance enhancements so the project in the simple cornel scene runs at about twice the speed(and some "change") at 33fps (512X512 scene with 4 hops at each path) instead of 13 at the same configuration Rendering is here 

I have also made spherical lights and organized the Light Class so that the addition of new types will be quick and easy

Here is the rendering with the three lights at 1024X1024 resolution

Next step will be to correct my errors in the BRDFs of the reflective and refractive materials