Well, I'm not really sure how the algorithm works for CSG, but for a simple
example of what I'm thinking of:

difference {
    isosurface {blah blah blah contained_by{ sphere{0,1} }}
    sphere { x,1 } // "sphere B"
}

If a ray hits the bounding sphere of the isosurface, but the point where it
hits it is *inside* sphere B, then it should not start checking
intersections of the isosurface. It should continue on until it hits the end
of sphere B. Then it should test to see if it's inside any *other* objects
in the difference, but ovbiously it's not in this case since there are no
other objects, so it should pretend as though it just entered the
isosurface, and start checking for intersections there.

Sort of as though the contained_by object itself were a CSG object.

If I sounded like I was challenging anyone in my previous post, I apologize,
I had no intention of doing so.

- Slime
[ http://www.teja.nu/slime/ ]
[ http://www.teja.nu/slime/images/ ]

"Ron Parker" <ron### [at] povrayorg> wrote in message
news:slr### [at] fwicom...
> On Mon, 24 Sep 2001 09:47:29 -0400, Slime wrote:
> >Oh, alright, sorry, I misread "max_trace" as "max_trace_level". Max_trace
> >fixed it. But how come in CSG it tests for parts of the isosurface
outside
> >of what has been cut off from the isosurface? Why doesn't it only test
the
> >parts of the isosurface that have a chance of being visible?
>
> And how exactly do you think it should go about doing that?
>
> --
> #local R=rgb 99;#local P=R-R;#local F=pigment{gradient
x}box{0,1pigment{gradient
> y pigment_map{[.5F pigment_map{[.3R][.3F color_map{[.15red
99][.15P]}rotate z*45
> translate x]}]#local H=pigment{gradient y color_map{[.5P][.5R]}scale
1/3}[.5F
> pigment_map{[.3R][.3H][.7H][.7R]}]}}}camera{location.5-3*z}//only my
opinions

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