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If this gives me a sphere:
isosurface { function { x^2+y^2+z^2-1 } }
why this doesn't:
#declare f1 = function { x }
#declare f2 = function { y }
#declare f3 = function { z }
isosurface { function { f1^2+f2^2+f3^2-1 } }
?
--
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/
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In article <387228ee@news.povray.org>, Nieminen Juha
<war### [at] punarastas cstutfi> wrote:
> If this gives me a sphere:
>
> isosurface { function { x^2+y^2+z^2-1 } }
>
> why this doesn't:
>
> #declare f1 = function { x }
> #declare f2 = function { y }
> #declare f3 = function { z }
> isosurface { function { f1^2+f2^2+f3^2-1 } }
>
> ?
I think there might be a bug with the isosurface functions when the
parameters are not specified. I think it should use (x, y, z) by
default, but this crashed MacMegaPOV when I tried it. Try using:
isosurface {
function {
f1(x, y, z)^2+
f2(x, y, z)^2+
f3(x, y, z)^2-1
}
}
instead.
--
Chris Huff
e-mail: chr### [at] yahoocom
Web page: http://chrishuff.dhs.org/
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From: Nieminen Juha
Subject: Re: Question about isosurface functions
Date: 4 Jan 2000 12:37:44
Message: <38722fe8@news.povray.org>
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Chris Huff <chr### [at] yahoocom> wrote:
: I think there might be a bug with the isosurface functions when the
: parameters are not specified. I think it should use (x, y, z) by
: default, but this crashed MacMegaPOV when I tried it. Try using:
: isosurface {
: function {
: f1(x, y, z)^2+
: f2(x, y, z)^2+
: f3(x, y, z)^2-1
: }
: }
: instead.
It didn't help.
--
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/
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In article <38722fe8@news.povray.org>, Nieminen Juha
<war### [at] punarastascstutfi> wrote:
> It didn't help.
Hmm, I don't know what's wrong. I tried a few things for myself, and
while it crashes when noise3d is used with no parameters, those
functions render with no trouble...but with no result. Also, these
doesn't work:
#declare f4 = function {x^2+y^2+z^2}
isosurface {function {f4(x, y, z)-1}}
#declare f4 = function {sqrt(x^2+y^2+z^2)}
isosurface {function {f4(x, y, z)^2-1}}
but these do:
#declare f4 = function {x^2+y^2+z^2}
isosurface {function {sqrt(f4(x, y, z))-1}}
#declare f4 = function {sqrt(x^2+y^2+z^2)}
isosurface {function {f4(x, y, z)-1}}
However, if you force method 1 solving, everything seems to work fine.
Just add the line "method 1" to the isosurface. Of course, this slows
things down.
Specifying a larger max_gradient(I tried 5) seems to work too. I would
guess maybe it is having trouble calculating the gradient of those
declared functions.
--
Chris Huff
e-mail: chr### [at] yahoocom
Web page: http://chrishuff.dhs.org/
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I'm afraid that I can't help you with you question, but I have another
similar question:
Why does y-exp(-(x^2)-(z^2)) render the same as y-exp(-(x^2)-z^2) but
differently from y-exp(-x^2-(z^2)) and y-exp(-x^2-z^2)?
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Order of math, the non-parenthesis parts will go last.
Bob
"Kevin Wampler" <kev### [at] tapestrytucsonazus> wrote in message
news:38723C50.47FAFFCE@tapestry.tucson.az.us...
> I'm afraid that I can't help you with you question, but I have another
> similar question:
>
> Why does y-exp(-(x^2)-(z^2)) render the same as y-exp(-(x^2)-z^2) but
> differently from y-exp(-x^2-(z^2)) and y-exp(-x^2-z^2)?
>
>
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On Tue, 04 Jan 2000 11:30:40 -0700, Kevin Wampler wrote:
>I'm afraid that I can't help you with you question, but I have another
>similar question:
>
>Why does y-exp(-(x^2)-(z^2)) render the same as y-exp(-(x^2)-z^2) but
>differently from y-exp(-x^2-(z^2)) and y-exp(-x^2-z^2)?
Without looking at the code, it looks like it's using too high a priority
for unary minus, so it's treating "-x^2" as "(-x)^2". BTW, I suspect you'd
get better performance with the sqr() function.
--
These are my opinions. I do NOT speak for the POV-Team.
The superpatch: http://www2.fwi.com/~parkerr/superpatch/
My other stuff: http://www2.fwi.com/~parkerr/traces.html
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That's what I thought, but upon closer examination, it appears to only assign
the unary minus a higher priority on the first term, so y-exp(-x^2-z^2)
renders differently from y-exp(-z^2-x^2). Good point about the sqr()
function, I hadn't realized that it was optimized.
> Without looking at the code, it looks like it's using too high a priority
> for unary minus, so it's treating "-x^2" as "(-x)^2". BTW, I suspect you'd
> get better performance with the sqr() function.
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On Tue, 04 Jan 2000 13:16:37 -0700, Kevin Wampler wrote:
>> Without looking at the code, it looks like it's using too high a priority
>> for unary minus, so it's treating "-x^2" as "(-x)^2". BTW, I suspect you'd
>> get better performance with the sqr() function.
>
>That's what I thought, but upon closer examination, it appears to only assign
>the unary minus a higher priority on the first term, so y-exp(-x^2-z^2)
>renders differently from y-exp(-z^2-x^2). Good point about the sqr()
>function, I hadn't realized that it was optimized.
>
The second term isn't a unary minus; it's the binary subtraction operator.
--
These are my opinions. I do NOT speak for the POV-Team.
The superpatch: http://www2.fwi.com/~parkerr/superpatch/
My other stuff: http://www2.fwi.com/~parkerr/traces.html
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<voice = Homer> doh! </voice>
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