[Bf-cycles] What are 'throughput' and 'weights'?

[Nikhilesh Sigatapu]

I was studying the cycles source code, and I think I'm beginning to 
understand it better. I was looking at the integration algorithm and two 
terms keep showing up - 'throughput' and 'weight'. What exactly do these 
signify in this context? I have a feeling throughput is some measure of 
the modulation across bounces (red surface modulated by red float3 for 
example), eventually becoming low and making probability of termination 
high.

I was also confused by closures for a bit, thinking it to be similar to 
the computer science term about functions, which seemed related to the 
execution context of shader functions. The way I see it now they are 
actually just shaders. Any clarification about this?

Thank you for your help, and the great cycles code!

-- 
Nikhilesh S
http://www.nikhilesh.info