In article <3f8a1ac3@news.povray.org>,
 "Hughes, B." <omn### [at] charternet> wrote:

> Themselves, yes; on a per individual primitive basis, having only a shadowed
> side versus lit side. So what I was saying is that if a sphere and cone are
> next to each other, in a union, they don't cast a shadow onto each other. I
> guess your explanation about bounding below is the reason why.

But they do...I'm not sure what you are saying. Are you talking about a 
bare union, a union with no_shadow, or a bare union as a looks_like 
object? A shadowless object won't self-shadow, but even a shadowless 
object has a lit side and a dark side.


> Just to give it a try, I checked what you suggested about manual bounding
> within the CSG union, except still for a looks_like object, and still aren't
> any shadows. I think it's been said that looks_like is only a shortcut to
> creating a light plus object, not the only way available and perhaps that's
> why no one has deemed it necessary to change. Or, as you said, there might
> be some difficulties is allowing shadowing via the internal bounding
> hierarchy?

The internal bounding heirarchy does not cause any problems with 
bounding. I was talking about the possibility of the union splitting 
behaving unexpectedly when combined with the looks_like feature. I think 
you're seeing a problem where there isn't one, or just not clearly 
explaining what the problem is...

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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"Christopher James Huff" <cja### [at] earthlinknet> wrote in message
news:cja### [at] netplexaussieorg...
> I think you're seeing a problem where there isn't one, or just not clearly
> explaining what the problem is...

Thought I was being clear in that I was checking this out by using a simple
CSG union of only a cone and sphere where it should cast a shadow from one
to the other's surface in a shadowable light. That CSG being used then as a
looks_like object, of course, doesn't have shadow but then neither does any
shadowing show from lights elsewhere.

I now know what you are saying about the self-shadowing though. I usually
take it to be that a dark side is a "self" shadow. What you meant is that a
torus, for example, with no_shadow applied does not cast a shadow across
itself from one edge to the other. I don't always get these characteristics
right but I do remember that being a classic example before.

This whole thing is really about whether or not shadowing caused by light
sources, other than the one containing it in a looks_like statement, would
exist. It doesn't seem correct to remove the shadow which could be produced
by all other light sources just because it's a looks_like object. For
instance, a light bulb casts a shadow from sunlight. This has been discussed
a lot before, I know.

Hopefully I'm getting somewhere with this.  :-)

-- 
Bob H.
http://www.3digitaleyes.com

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In article <3f8aaa18@news.povray.org>,
 "Hughes, B." <omn### [at] charternet> wrote:

> I now know what you are saying about the self-shadowing though. I usually
> take it to be that a dark side is a "self" shadow. What you meant is that a
> torus, for example, with no_shadow applied does not cast a shadow across
> itself from one edge to the other. I don't always get these characteristics
> right but I do remember that being a classic example before.

What you are thinking of is double-illumination, or rather the lack of 
it. You could consider it a kind of shadowing, but the light isn't being 
blocked from reaching the surface, it's just on the other side of it.


> This whole thing is really about whether or not shadowing caused by light
> sources, other than the one containing it in a looks_like statement, would
> exist. It doesn't seem correct to remove the shadow which could be produced
> by all other light sources just because it's a looks_like object. For
> instance, a light bulb casts a shadow from sunlight. This has been discussed
> a lot before, I know.

I agree.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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