I'm working on a blob-model, and trying to figure out how to get a sharp
point from blobs... is it possible?  I'd like to create a sort of
teardrop shape, with one end rounded, and the other end pointed, but,
there being no torus in blob-land to apply negative strength to, I'm not
sure how to do this.

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In article <3ACCB00A.B7AAD1AA@mac.com>, Dawn McKnight 
<McK### [at] maccom> wrote:

> I'm working on a blob-model, and trying to figure out how to get a sharp
> point from blobs... is it possible?  I'd like to create a sort of
> teardrop shape, with one end rounded, and the other end pointed, but,
> there being no torus in blob-land to apply negative strength to, I'm not
> sure how to do this.

I'd just use an isosurface...but you might get what you want by using a 
while loop to generate a line of spherical components decreasing down to 
nearly 0 radius.

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

<><

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if you space two blobs components at the right
distance, the connecting ribbon can be made very
thin.Then difference one of the blob components
out and you should end up with one left in a tear-drop
shape.
No time now but will try to get you an example
when I get home from work (a day or 2)

Y

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"yooper" <Out### [at] huntelnet> wrote in message
news:3acce396@news.povray.org...
> if you space two blobs components at the right
> distance, the connecting ribbon can be made very
> thin.Then difference one of the blob components
> out and you should end up with one left in a tear-drop
> shape.

That's how I've done it before too, while looping the point could be easier
though.
Always seems to be tricky to get just the right distance separation for the
pinched connection, and then you have to locate just the right place for the
differencing away of the other component.

> No time now but will try to get you an example
> when I get home from work (a day or 2)

Chris's isosurface method seems more plausible to me actually.
Here's my try at it, but probably not the shape you want.  More of what I
think I read a real raindrop shape is, ie. convexly (that a word?) rounded.

#version unofficial MegaPov 0.7;

// lobes II (raindrop)
#declare F13=function {(sin(y^1.67)+(x+(.485)+z)-(x*x+cos(y*.515)+z*z))}
isosurface {function {F13}
 contained_by {sphere {<.5,-1.33,.5>,1.33}} // yow, this sure had to be
moved around!
 sign -1
 eval
 accuracy .01
  pigment {rgb 1}
 scale <1,1.25,1>
}

camera {
        location <0,0,-10>
        angle 30
        look_at -y
}

light_source {<-25,7.5,-150>,1.25}

One (heck of a messy) way to do it anyhow.

Bob H.

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Chris Huff wrote:

> I'd just use an isosurface...but you might get what you want by using a
> while loop to generate a line of spherical components decreasing down to
> nearly 0 radius.

Or a good old quartic... "Piriform" does nice teardrop shapes, as does this
even simpler bit of code from Ken Tyler.

G.

  #include "colors.inc"
  camera{location -3*z look_at 0}
  background{rgb .5}
  light_source {<1,.4,-1>*1000 color White}
  light_source {<-1,1,-1>*500 color White*0.3}

  #declare Drop =
  quartic{<0,0,0,0,0,0,0,0,0,-4,0,0,0,0,0,0,0,0,0,0,
           0,0,0,0,0,-4,0,0,0,0,-1,2,0,-2,1> sturm}

    object { Drop rotate x*-90
   texture {
   pigment { rgbf<0.9,0.9,0.9,0.7>}
    finish { ambient 0.3 diffuse 0.3 specular 1 roughness 0.001 reflection
0.2}
           }
  interior { ior 1.15 }
           }


--

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