sun angle visualization

[holbrd]

I found online a video on youtube done by Lan livearchitecture.net it
is an example of how to use grasshopper as an analytical tool
displaying the radiance of light on a surface and shadow projection. I
have been having trouble trying to recreate this file. Does anyone
have an idea on how to do so?, I haven't dealt to much with colors
before.The video is at http://www.youtube.com/watch?v=udyD2qWDAVQ