The why of the problem is easy.  Fixing might be a little tougher.

When the ray intersects the surface, additional rays are sent towards
all lights to determine diffuse/specular effects.  The light inside the
surface is included in this operation.

If you were working with physical objects, this wouldn't happen because
you don't have 2D surfaces.  In order to get around this "problem" in
renderers, there is usually a flag to say you don't want to shade
backsides of surfaces.  The backside being defined in several ways,
including orientation of vertices, direction of normal, etc.  Another
way this problem is obviated in renderers is turning on/off what lights
can illuminate a particular object.

What to do with Moray/POV-Ray?  Not sure - Mega POV might offer a little
more control over single/double sided shading or controlling of lights. 

If you were using something other than a patch, I'd suggest making your
object from a CSG and ensuring you have an inner surface as well as an
outer one - like subtracting a box from another box to make a room, then
differencing boxes from the walls to make window holes.

Xander


> 

> Hi there,
> i have a little problem with spatch-created objects and povray (moray).

> I have created a  body with spatch with a window. Now i want to set a
> lightsource inside the body, so that the light will shine through the
> window. Unfortunately, the whole body glows, like it is opaque (what it

> isn't!).
> 

> Can anybody help me, what i'm doing wrong?
> 

> Bob

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