"Lux Contour" coloring techniques

[amanzi]

Hi Folks,

I am new to Sketchup and am considering having a Plugin or extension written for an engineering application that "paints surfaces" in a similar manner to lighting tools that display "lux contours". The intensity (represented by a color) of a portion of a surface or face is determined by a calculation similar to lighting intensity with multiple point light sources. The result needs to be part of the Sketchup model and not simply rendered image from one perspective. Not being a 3D rendering or Sketchup expert I wondering if someone could explain to me (or point me in the direction of) the techniques used to "paint" a portion of a surface or face a chosen color using the Ruby API or an extension. Some of the commercial lighting software appears to take advantage of OpenGL capabilities but after scanning through the Ruby API and Googling I am none the wiser.

Thanks for your help.

[remus]

Lightup sounds like it does roughly what you want, i'm not sure to what extent you can bake the textures in, though.

Your best bet would probably be to send adamb a PM about it, he'll be able to give you better answers than i can: http://www.sketchucation.com/forums/scf/ucp.php?i=pm&mode=compose&u=1200

edit: speak of the devil.

[AdamB]

The basic technique is to have the ability to set up light sources in your model and then evaluate the lighting on every point in your model surfaces. The high dynamic range results you get need to be mapped down to a linear color space which you use to actually paint the results.

Now I appreciate you might reply "well of course you'd say that", but.. doing what you ask requires quite a lot of infrastructure to support - ie its a lot of work. And as you've found from the APIs, there isn't much there to help in this respect because they (not unreasonably) focus on geometry manipulation and not light transfer.

Adam

edit: I must be a devil to have avoided the blockade in Calais.. Just arrived after 1400km in a car with 2 small children.. luuvely. No really it was, no really. I'll leave now.

[amanzi]

Thanks Adam - I am actually trying your program as you speak as an example of what the display could look like and it looks great but I am not looking for a lighting tool. My equivalent "lighting effect" is created by custom radiation functions that depend on the type of source, the distance from the source, and blockage and are not light sources. I am not lookig for photo realism but for a representation of intensity on surfaces. The essence of my question is: what technique could be used to color small portions of the Sketchup drawing? The resolution I am looking for is typically 30 cm square for drawings that are the size of a building. Is there some way to divide up each face of every entity and assign a color to it based on the result of my "radiation function" as the point.

Perhaps this is part of the infrastructure you mention?

Thanks for your help.