is it possile to make an isosurface from a function F(r,theta,phi) in
spherical coordinates? or do I have to convert to cartesian or create a
set of parametric equations..... 


-paul
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--------------------------------------------------}
Paul Daniel Jones
The Pennslyvania State University

pdj### [at] psuedu
http://research.chem.psu.edu/glassgrp/paul

       C            The way is near, but men
     // \           seek it afar. It is in the
    N    N          easy things, but men seek it
    |    ||         in the difficult things.
    C    C          -Menicius
     \\  /
       C
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Paul Jones wrote:
> 
> is it possile to make an isosurface from a function F(r,theta,phi) in
> spherical coordinates? or do I have to convert to cartesian or create a
> set of parametric equations.....
> 
> -paul

IMO you have to use cartesian coordinates, maybe have a look on the megapov
sample file 'sph_noise.pov', which uses something like noise3d with spherical
coordiantes.  

Christoph

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

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In article <39AFCCBA.F91D7D07@psu.edu>, Paul Jones <pdj### [at] psuedu> 
wrote:

> is it possile to make an isosurface from a function F(r,theta,phi) in
> spherical coordinates? or do I have to convert to cartesian or create a
> set of parametric equations..... 

Just use functions to convert the cartesian coordinates to spherical 
coordinates. There are many examples of these functions out there, just 
guessing I would write:
#declare R = function {sqrt(sqr(x) + sqr(y) + sqr(z))}
#declare Phi = function {atan2(x, z)}
#declare Theta = function {atan2(y, sqrt(sqr(x) + sqr(z)))}

I might have Phi an Theta backwards or going the wrong direction(or 
completely wrong, since I am going from memory), but this gives the 
general idea. Just feed these functions the xyz cartesian coordinates 
and use the result as the spherical coordinates.

-- 
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 wrote:
> 
> Just use functions to convert the cartesian coordinates to spherical
> coordinates. There are many examples of these functions out there, just
> guessing I would write:
> #declare R = function {sqrt(sqr(x) + sqr(y) + sqr(z))}
> #declare Phi = function {atan2(x, z)}
> #declare Theta = function {atan2(y, sqrt(sqr(x) + sqr(z)))}
> 
> I might have Phi an Theta backwards or going the wrong direction(or
> completely wrong, since I am going from memory), but this gives the
> general idea. Just feed these functions the xyz cartesian coordinates
> and use the result as the spherical coordinates.
> 

You made way to much thoughts about it :-)

There are already predefined functions in megapov:

	"R" = sqrt(x*x+y*y+z*z) 
	"TH" = atan2(x,z) 
	"PH" = atan2(sqrt(x*x + z*z ),y) 

Anyway my respect for you doing it from memory.

Christoph

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

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In article <39AFD6EE.18DEFE73@schunter.etc.tu-bs.de>, 
chr### [at] gmxde wrote:

> You made way to much thoughts about it :-)
> 
> There are already predefined functions in megapov:
> 
> 	"R" = sqrt(x*x+y*y+z*z) 
> 	"TH" = atan2(x,z) 
> 	"PH" = atan2(sqrt(x*x + z*z ),y) 
> 
> Anyway my respect for you doing it from memory.

But those functions have a strange syntax and may not make it into 3.5. 
If they do make it into 3.5, it will be with a different syntax. 
However, it is quite probable that the declared functions will still 
work properly.

-- 
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 wrote:
> 
> But those functions have a strange syntax and may not make it into 3.5.
> If they do make it into 3.5, it will be with a different syntax.
> However, it is quite probable that the declared functions will still
> work properly.
> 

With strange syntax, do you mean these special fuctions or the "string
functions" in general ?

Christoph

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

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In article <39AFDAF8.A3763004@schunter.etc.tu-bs.de>, 
chr### [at] gmxde wrote:

> With strange syntax, do you mean these special fuctions or the "string
> functions" in general ?

I mean all of "built-in library" functions that you access with a string 
and pass parameters with a vector. Not the built-in "standard" functions 
like atan2, sin, etc.

-- 
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 wrote:
> 
> I mean all of "built-in library" functions that you access with a string
> and pass parameters with a vector. Not the built-in "standard" functions
> like atan2, sin, etc.
> 

I see, that's what i implied in the question. 

I'm eager to see how those things are handled in Povray 3.5 ...

Christoph

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

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Christoph Hormann wrote:

> You made way to much thoughts about it :-)
>
> There are already predefined functions in megapov:
>
>         "R" = sqrt(x*x+y*y+z*z)
>         "TH" = atan2(x,z)
>         "PH" = atan2(sqrt(x*x + z*z ),y)
>
> Anyway my respect for you doing it from memory.

Bah, give him a harder question

--
David Fontaine   <dav### [at] faricynet>   ICQ 55354965
Please visit my website:  http://davidf.faricy.net/

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So, a train leaves San Fransisco heading east at 120 km hr^-1 and there
is a turtle crossing the tracks in Phoenix at a rate of 0.01m hr^-1.
What is the price of tomatoes in Ireland?

just kidding.

Thanks for the help. My math is a bit rusty....


-paul

David Fontaine wrote:

> Christoph Hormann wrote:
>
> > You made way to much thoughts about it :-)
> >
> > There are already predefined functions in megapov:
> >
> >         "R" = sqrt(x*x+y*y+z*z)
> >         "TH" = atan2(x,z)
> >         "PH" = atan2(sqrt(x*x + z*z ),y)
> >
> > Anyway my respect for you doing it from memory.
>
> Bah, give him a harder question
>
> --
> David Fontaine   <dav### [at] faricynet>   ICQ 55354965
> Please visit my website:  http://davidf.faricy.net/

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Paul Daniel Jones
120 Chandlee Laboratory
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814-865-2090
pdj### [at] psuedu

http://research.chem.psu.edu/glassgrp/paul
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