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OT: Please note the correct spelling of millennium.
;)
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Remco de Korte <rem### [at] xs4all nl> wrote
> There's one drawback to your suggestion: an object wouldn't be lit be a
> lightsource but it would cast a shadow, wouldn't it? What would happen if
it is
> a shadowless light_source (I tend to use lots of those).
*Then* you would need a selective lighting patch. However, if you want
*no* shadows on something, you could make it luminous by using ambient.
-Robert
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Ron Parker <par### [at] fwi com> wrote
> Anyway, there's an easier way to get that effect:
>
> #declare LightPos=<...>;
> #declare ShadowOnlyObject=...
>
> light_source { LightPos rgb 1}
> object { ShadowOnlyObject bounded_by {sphere { LightPos .001 }}}
Cool. This doesn't look as if it *ought* to work, because POV-Ray has an
absolute concept of "inside" - but it does. Clearly the shadow test uses ray
intersections to determine whether a "legal" part of the object is blocking
light, so is fooled if the lightsource is inside the bounding object.
-Robert Dawson
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On Fri, 11 Jun 1999 10:30:18 -0300, Robert Dawson wrote:
>
>Ron Parker <par### [at] fwi com> wrote
>
>> Anyway, there's an easier way to get that effect:
>>
>> #declare LightPos=<...>;
>> #declare ShadowOnlyObject=...
>>
>> light_source { LightPos rgb 1}
>> object { ShadowOnlyObject bounded_by {sphere { LightPos .001 }}}
>
> Cool. This doesn't look as if it *ought* to work, because POV-Ray has an
>absolute concept of "inside" - but it does. Clearly the shadow test uses ray
>intersections to determine whether a "legal" part of the object is blocking
>light, so is fooled if the lightsource is inside the bounding object.
The reason this works is that POV first checks for an intersection with
the bounding object before looking for intersections with the real object.
The only rays that intersect the bounding object are shadow rays, so they
are the only rays that are tested against the real object. Camera rays
and reflected rays don't hit the bounding object (usually) so POV assumes
that they also don't hit the real object.
You can also use this trick to make a vampire object (no reflection and
no shadow) by bounding with a small sphere around the camera.
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Lance Birch wrote in message <3760cf08@news.povray.org>...
>OT: Please note the correct spelling of millennium.
>
>;)
As I am from the USA, I can spell millinium however I want :-)
Mark
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Nieminen Mika wrote:
> Yeah, interesting.
>
> light_source { ... }
>
> object // Lit by the global light source
> { MyObject1
> }
>
> object // Lit by the global light source and an own light source
> { MyObject2
> lit_by { light_source { ... } }
> }
[snip]
VRML has a class of lights, DirectionalLights, which are scoped so
as to light all and only the geometry nodes under their own parent,
while all the other lights are global in scope.
I had pushed the "reply" button to say that I thought that this was
an easier syntax than you'd sketched above, but by the time I got
to this sentence, I thought maybe that might be a mistake. I'm
guessing that nobody's really exercised the hierarchical scene
graph features in POVRay, and that while VRML scenes with 10 levels
of nesting are far from unusual, I've never seen even one that deep
in POVRay. Putting in something that would motivate people to make
deeply nested scenes could turn out to be a huge opportunity to
generate bug reports.
+-------------------------------+--------------------------------------+
| Rev. Bob "Bob" Crispen | "IT FOUND ME!" |
| cri### [at] hiwaay net | Campus Crusade for Cthulhu |
+-------------------------------+--------------------------------------+
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Got to about 15 levels in one project. Debugging was a veritable pain, and
ultimately failed. No, thanks!
I could post an unindented version just for Ken's enjoyment... Nah.
Margus
Bob Crispen wrote in message <376231DD.494F3821@hiwaay.net>...
>
>I'm
>guessing that nobody's really exercised the hierarchical scene
>graph features in POVRay, and that while VRML scenes with 10 levels
>of nesting are far from unusual, I've never seen even one that deep
>in POVRay. Putting in something that would motivate people to make
>deeply nested scenes could turn out to be a huge opportunity to
>generate bug reports.
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Will the next superpatch support 3.1e?
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Steven Jones wrote:
>
> Will the next superpatch support 3.1e?
It now does. Get the 3.1e version at:
http://www2.fwi.com/~parkerr/superpatch/
--
Ken Tyler
mailto://tylereng@pacbell.net
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