news:404c835d@news.povray.org...

> So my question was, since I have never had any experience with such a
> tool first hand, does it indeed obviate any need for manually
> rearranging vertex mappings on a uv template, such as we get involved in
> when using uvmapper?

From what I've seen, no. You still have to move the vertices yourself if
necessary, due to the limitations of the uv wizards. The added productivity
is due to the following 1) the wizards are more sophisticated than the
primitives (box, sphere, cylinder) offered by UVMapper and 2) real-time
painting which removes the usual worries about putting paint at the right
place. But it's still quite theoretical to me and I still need to plunge
headfirst in a real BP project before I can really talk about it.

G.

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Jim Charter <jrc### [at] msncom> wrote:
> How is it that case 1 gets a performance/memory gain and case 2 doesn't?

  When you create instances of a mesh, the mesh data is not copied. However,
when creating instances of a union, the contents are copied for each
instance.
  The reason is that transformations made to the instance may change the
contents of the union.
  In order to get the same advantage as with a mesh, all transformation
optimizations would need to be removed from all existing primitives.
This might have a negative impact on the rendering speed of some
scenes... (It's not an impossible idea, but it would be nice to know
how much it would impact in practice.)

-- 
plane{-x+y,-1pigment{bozo color_map{[0rgb x][1rgb x+y]}turbulence 1}}
sphere{0,2pigment{rgbt 1}interior{media{emission 1density{spherical
density_map{[0rgb 0][.5rgb<1,.5>][1rgb 1]}turbulence.9}}}scale
<1,1,3>hollow}text{ttf"timrom""Warp".1,0translate<-1,-.1,2>}//  - Warp -

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Warp wrote:
> Jim Charter <jrc### [at] msncom> wrote:
> 
>>How is it that case 1 gets a performance/memory gain and case 2 doesn't?
> 
> 
>   When you create instances of a mesh, the mesh data is not copied. However,
> when creating instances of a union, the contents are copied for each
> instance.
>   The reason is that transformations made to the instance may change the
> contents of the union.
>   In order to get the same advantage as with a mesh, all transformation
> optimizations would need to be removed from all existing primitives.
> This might have a negative impact on the rendering speed of some
> scenes... (It's not an impossible idea, but it would be nice to know
> how much it would impact in practice.)
> 
Thanks Warp, that helps.  For the record, I did check your FAQ before 
asking.

Two follow up questions if I may...

I have:

#local Shape =
sphere { ... }

#local Pattern =
union {
	sphere { ... }
	sphere { ... }
	...
}

#local Result =
object { Shape
	clipped_by { Pattern }
}

LOOP ( many times )
	object { Result translate ... }
END LOOP

1) How expensive is this...
compared with if Result was just a simple unclipped sphere 			primitive? 
  ie If the clipping Pattern is some complex thing, how does that 
contribute to the expense of the instantiated Result?

2) Is there any general way of estimating computational expense of 
different primitives?  ie Are two triangle primitives exactly twice as 
expensive as one box?

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I just noticed this thread this morning and thought I'd put in my two cents
worth. I highly recommend Moray 3.5 for mesh2 modeling. Moray will produce a
UV map of the mesh object, flattened out into 2D. For my head model which I
posted to p.b.i., I made a screenshot of the 2D UV map and imported it into
Corel PhotoPaint, where I was able to paint over it on new layers, being
able to see where everything I painted would show up on the UV map. After
doing all the painting I wanted, I deleted the UV map screenshot layer,
combined the newly painted layers into a .jpg file, which I then used for
the UV map texture for the mesh. Everything painted on the flat surface goes
exactly where it should on the 3D mesh.
Steve Shelby

"Jim Charter" <jrc### [at] msncom> wrote in message
news:40479763@news.povray.org...
snip

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I agree with you whole-heartedly on the value of SDL.  While mesh models
certainly are valuble for many things, as a machinist I daily carve parts
out of solid blocks of metal and simply THINK in CSG.  The ablity of POV to
use multi-dimensional, array defined, splines is a powerful yet poorly
documented feature that has taken it out of hobby status and solidly put it
on my workbench.  I hope in future versions to see more tools like pipes to
get the data directly into CAD/CAM instead having to dump via #debug into a
file.


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