In article <3A0CEB66.142B670F@mac.com>, mck### [at] maccom wrote:

> Chris H., thanks for the macro.  I hadn't thought about doing that.

You're welcome... :-)


> I'm finding I don't understand the concept of area_light very well, and
> I was wondering if someone could clarify it for me?  Looking at page 222
> of the official documentation, I read that the syntax is:
> 
> light_source { <location>, COLOR area_light <Axis_1>, <Axis_2>, Size_1,
> Size_2 [adaptive ADAPTIVE] [jitter JITTER] [LIGHT_MODIFIERS] }
> 
> What I don't understand is the axis_1 and axis_2.  The descriptive
> paragraph just above the syntax says that an area light is a one or
> two-dimensional area of space.  

I have always interpreted it this way: the <location> vector specifies 
the center of the source, the two <Axis_x> vectors specify the 
directions and extents of the rectangle, and the Size_x values specify 
the "resolution" of the area light. The area light would go from 
<location>-Axis_1-Axis_2 to <location>+Axis_1+Axis_2.
The documentation is pretty vague though, and I have very rarely used 
area lights, so I could easily be wrong...


> If it is the first one, how do you use this with the looks_like
> argument?  You'd get half of your cylinder, for instance, lit... or even
> a quarter of it, depending on how the object is displayed around the
> <location> argument.

looks_like simply places a copy of the looks_like object at the location 
of the light source. The looks_like object will automatically be made 
shadowless, but will be lit normally(I personally have never used 
looks_like, I prefer to use unions of objects with the light source). 
Also, area lights only affect shadows, not surface shading, so there is 
no reason for only half of the object to be illuminated.


> As an afterthought, can anyone suggest a good texture for simulating 
> leather?

Depends on what you want, "leather" can have a lot of different colors 
and textures. A fairly simple pigment with a crackle, granite, or 
wrinkles normal would probably work well...

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

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