Bill DeWitt wrote:
> 
>     I like to think that -anything- can be done with isosurface if one can
> figure out the formula. I cannot figure out anything but the basics, and
> some random thrashing around with those. But I am still struggling with an
> isosurface tree. So far I haven't even been able to reach my first goal, a
> "Y"...

:-)

I just wrote some thoughts i had, maybe i will try it out myself sometime, it
should really be more simple than a realistic tree ...

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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Bill DeWitt wrote:

> But I am still struggling with an
> isosurface tree.

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"Greg M. Johnson" <"gregj;-()"@aol.c;-()om> wrote in message
news:39f5982d@news.povray.org...
>
>
> Bill DeWitt wrote:
>
> > But I am still struggling with an
> > isosurface tree.
>
> Did you see my example at p.b.i.:

    Yes I did, but I was thinking of working from the trunk out, yours seems
to model the outer leaves only.... or do I misunderstand it?

    I want to make a branching shape that I can then put leaves on. I
suspect that it can be done, but I haven't been able to get anywhere with it
at all.

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In article <39f5b947$1@news.povray.org>, "Bill DeWitt" 
<the### [at] earthlinknet> wrote:

>     I want to make a branching shape that I can then put leaves on. I
> suspect that it can be done, but I haven't been able to get anywhere 
> with it at all.

I whipped up this isosurface tree in about 20 minutes...but I cheated. 
:-)
I made a fractal blob, then used the blob pattern in a pigment in a 
pigment function, and called that function from the isosurface. Not too 
slow...and it still has many of the benefits of isosurfaces.

I don't think you are going to get a realistic looking, complex plant 
out of an ordinary function...it would certainly be possible, but the 
function would probably be horribly complex, inflexible, and slow 
rendering. Maybe if you designed some new pattern and used that in the 
isosurface...
You can get some odd branch-like structures that look fairly natural 
from a distance pretty easily, just by displacing a sphere with a 
pigment. Not exactly a tree though...

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

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"Chris Huff" <chr### [at] maccom> wrote :
>
> I whipped up this isosurface tree in about 20 minutes...but I cheated.
> :-)

    Sure did! Cheaters never prosper....

> I don't think you are going to get a realistic looking, complex plant
> out of an ordinary function...

    Don't say things like that!

    I don't really think I will get it no matter if it is possible or not.
Below is how far I got today. And as I said, all I am trying for is a simple
"Y".

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In article <39f62a60@news.povray.org>, "Bill DeWitt" 
<the### [at] earthlinknet> wrote:

> Below is how far I got today. And as I said, all I am trying for is a 
> simple "Y".

Just a "Y"? That's easy...
function {if(-y, R1(x,y,z), R1(-abs(x)+y,y,z))-1}

Getting the branches to branch is what would make the function so 
complex, and getting random variations in branch numbers, size, length, 
etc. will be even more difficult. And the result probably won't render 
in a reasonable speed.

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

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Bill DeWitt wrote:
> 
> > And the result probably won't render
> > in a reasonable speed.
> 
>     Well see that is what I was hoping you wouldn't say. There are
> various -great- tree macros to be had, but I was assuming that an isosurface
> would be quicker.

Concerning efficiency, both a macro tree and a (hypothetical) isosurface have
advantages, the macro tree would probably render faster as a single object
(assuming both are equally complicated), but when placing a lot of trees in one
scene, the isosurface has strong advantages because of fewer memory use.  

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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Christoph Hormann wrote:

> Concerning efficiency, both a macro tree and a (hypothetical) isosurface have
> advantages, the macro tree would probably render faster as a single object
> (assuming both are equally complicated), but when placing a lot of trees in one
> scene, the isosurface has strong advantages because of fewer memory use.

LSystmes were designed for this purpose but have a bit of a learning
curve involved. Too bad there are no really good LSystem modelling
programs available.

-- 
Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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Ken wrote:
> 
> LSystmes were designed for this purpose but have a bit of a learning
> curve involved. Too bad there are no really good LSystem modelling
> programs available.
> 

L-Systems have the same disadvantages as tree macros (IIRC most tree macros are
essentially specialized l-systems with some improvements).  

BTW, a l-system modelling program would be quite difficult, because l-systems
are coded in fact and therefore can't be modelled, you could only try to
generate the l-system definition from some modelled shape, but that would not be
of much use IMO.

Attached are two coniferous trees i made with l-systems some years ago.

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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