Warp napsal(a):
> Jaap Frank <jjf### [at] casemanl> wrote:
>> Because triangles are not solid objects but surfaces only, you can't carve 
>> something out of it.
> 
>   No primitive in POV-Ray is solid. Everything is just a surface.
> 
>   What "solid" means in terms of CSG is that some points can be defined
> to be "outside" the surface and others "inside" it. Thus "closed surface"
> would be a much more accurate term than "solid".
> 
>   The problem with eg. the triangle primitive is that it's not a closed
> surface, but on open one. Thus it can't have a defined interior (ie. there
> aren't points which can be said to be "inside" a triangle).
> 
>   OTOH, a closed triangle mesh can be defined as being "solid" because
> POV-Ray can determine whether a point is inside this closed mesh or not.
> This can be done by using the inside_vector feature of meshes.
> 
well, umm, thanks. And remember the sun doesn't move. But that doesn't 
stop us from saying it does. I often say the sun has moved behind the 
even though there is no such thing as a horizon and the doesn't move at 
all (well, it does). It is because the result is the same (up to some 
feeble effects).

By saying "a sphere is solid" i imply "with respect to the context" and 
I mean "a sphere behaves just like it was solid" i.e. "you can do CSG 
with spheres". (actually, the sphere *doesn't* behave, it has no brain).
What I'm trying to say, people often describe what do objects do 
(interface) rather than how do they do it (implementation).

Your comment would be appropriate as a response to someone claiming the 
raytracer considers the whole object interior when raytracing it. IMO 
your comment is inappropriate here I don't mean to be rude, I simply 
find it strange that you defend something that's not being denied. If 
not inappropriate, your comment is not very hepful (neither is mine, I 
admit)

-- 
You know you've been raytracing too long when...
you ever saw a beautiful scenerey and regretted not to take your 6" 
reflective ball and a digital camera, thinking "this would have been a 
perfect light probe"
-Johnny D

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