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Why does this show nothing?
#declare PigFun = function {
pigment {
granite
color_map { [0 rgb 0] [1 rgb 1] }
}
}
isosurface {
function { -PigFun + (sqr(x)+sqr(y)+sqr(z)) }
contained_by { sphere { 0,2 }}
pigment { rgb 1 }
}
--
Anton Sherwood -- br0### [at] p0b0x com -- http://ogre.nu/
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In article <399EE07F.65720247@pobox.com>, Anton Sherwood
<bro### [at] pobox com> wrote:
> Why does this show nothing?
You don't specify a threshold, so it defaults to 0. Your function only
evaluates to 0 at a few points(if it ever does), so surfaces are found.
Try using a threshold of 0.5 for some results.
isosurface {
function {sqr(x) + sqr(y) + sqr(z) - PigFun(x,y,z)}
threshold 0.5
contained_by {sphere {0, 2}}
pigment {rgb 1}
}
--
Christopher James Huff
Personal: chr### [at] mac com, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tag povray org, http://tag.povray.org/
<><
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> Anton Sherwood <bro### [at] pobox com> wrote:
> > Why does this show nothing?
Chris Huff wrote:
> You don't specify a threshold, so it defaults to 0. Your function only
> evaluates to 0 at a few points(if it ever does),
Eh? -PigFun + r^2 ought to be negative somewhere within the unit
sphere.
> so [no] surfaces are found.
> Try using a threshold of 0.5 for some results.
Okay.
Why does this show nothing?
#declare PigFun = function {
pigment {
granite
color_map { [0 rgb 0] [1 rgb 1] }
}
}
isosurface {
function { -PigFun + (sqr(x)+sqr(y)+sqr(z)) }
threshold 0.5 // likewise 1
contained_by { sphere { 0,2 }}
pigment { rgb 1 }
}
--
Anton Sherwood -- br0### [at] p0b0x com -- http://ogre.nu/
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In article <39A00F7A.546A262F@pobox.com>, Anton Sherwood
<bro### [at] pobox com> wrote:
> Eh? -PigFun + r^2 ought to be negative somewhere within the unit
> sphere.
Er, you are right, of course...for some reason I was adding, not
subtracting. Oops.
Try specifying a max_gradient or eval. Sometimes this is necessary to
get a correctly rendering surface. And you might want to try "function {
-PigFun + sqrt(sqr(x)+sqr(y)+sqr(z)) }", so it falls off linearly from
the center.
--
Christopher James Huff
Personal: chr### [at] mac com, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tag povray org, http://tag.povray.org/
<><
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