I've posted information about this image in povray general.

I'm requesting some help for creating a small object.  I want to basically
wrap a rounded spiral around a sphere.


Patrick Dugan

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Attachments:
Download 'SpiralSphere.jpg' (11 KB)

Preview of image 'SpiralSphere.jpg'

This is probably the simplest way
Just start at the top
Put an object at <cos(pi/2)*radius, sin(pi/2)*radius, 0>
Incremently increase your angle from pi/2 to 3*pi/4
each time you place an object, rotate it a little bit around the y-axis

Hope this helps,
 -Shay


"Patrick Dugan" <pat### [at] netinsnet> wrote in message
news:3c5dcaf2@news.povray.org...
> I've posted information about this image in povray general.

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Well I probably butchered the formula but here is what I made:

#declare MinRad = pi/2;
#declare MaxRad = (3*pi/4)*10;
#declare Test =
union {
   #while (MinRad < MaxRad)
      object {sphere {<0,0,0>, 0.1 translate <cos(MinRad)*1, sin(MinRad)*1,
MinRad/10> pigment {Red}}}
   #declare MinRad = MinRad + 0.01;
   #end
}

object {Test rotate x * -90 translate <0,-2,0>}

This created a spiral but always the same distance from the center.  I was
trying to make something that would get closer to the center as it moved up
or down.
What did I do wrong?  (I'm sorry my math skills are really poor...)



"Shay" <shi### [at] houstonrrcom> wrote in message
news:3c5dcd84@news.povray.org...
>
> This is probably the simplest way
> Just start at the top
> Put an object at <cos(pi/2)*radius, sin(pi/2)*radius, 0>
> Incremently increase your angle from pi/2 to 3*pi/4
> each time you place an object, rotate it a little bit around the y-axis
>
> Hope this helps,
>  -Shay
>
>
> "Patrick Dugan" <pat### [at] netinsnet> wrote in message
> news:3c5dcaf2@news.povray.org...
> > I've posted information about this image in povray general.
>
>
>

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I'm sorry. 3*pi/4 should have been 3*pi/2
You don't need to translate the spiral any along the y-axis. Setting x and y
to the cos and sin of the angle will do that for you.
The formula itself zill make a half-moon arc. Rotating each sphere some will
give you the twist.
Like this:
#declare MinRad = pi/2;
#declare MaxRad = (3*pi/2);
#declare Test =
union {
   #while (MinRad < MaxRad)
      object {sphere {<0,0,0>, 0.01 translate <cos(MinRad)*1, sin(MinRad)*1,
0> rotate y*degrees(MinRad)*20 pigment {rgb <1,0,0>}}}
   #declare MinRad = MinRad + 0.0001;
   #end
}

object {Test /*rotate x * -90 translate <0,-2,0>*/}

#declare MinRad = pi/2;
#declare MaxRad = (3*pi/2);
#declare Test =
union {
   #while (MinRad < MaxRad)
      object {sphere {<0,0,0>, 0.01 translate <cos(MinRad)*1, sin(MinRad)*1,
0> rotate y*degrees(MinRad)*20 pigment {rgb <1,0,0>}}}
   #declare MinRad = MinRad + 0.0001;
   #end
}

object {Test /*rotate x * -90 translate <0,-2,0>*/}
"Patrick Dugan" <pat### [at] netinsnet> wrote in message
news:3c5dddaf$1@news.povray.org...
> Well I probably butchered the formula but here is what I made:

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That is perfect!!

Thank you!


"Shay" <shi### [at] houstonrrcom> wrote in message
news:3c5de13b$1@news.povray.org...
> I'm sorry. 3*pi/4 should have been 3*pi/2
> You don't need to translate the spiral any along the y-axis. Setting x and
y
> to the cos and sin of the angle will do that for you.
> The formula itself zill make a half-moon arc. Rotating each sphere some
will
> give you the twist.
> Like this:
> #declare MinRad = pi/2;
> #declare MaxRad = (3*pi/2);
> #declare Test =
> union {
>    #while (MinRad < MaxRad)
>       object {sphere {<0,0,0>, 0.01 translate <cos(MinRad)*1,
sin(MinRad)*1,
> 0> rotate y*degrees(MinRad)*20 pigment {rgb <1,0,0>}}}
>    #declare MinRad = MinRad + 0.0001;
>    #end
> }
>
> object {Test /*rotate x * -90 translate <0,-2,0>*/}
>
> #declare MinRad = pi/2;
> #declare MaxRad = (3*pi/2);
> #declare Test =
> union {
>    #while (MinRad < MaxRad)
>       object {sphere {<0,0,0>, 0.01 translate <cos(MinRad)*1,
sin(MinRad)*1,
> 0> rotate y*degrees(MinRad)*20 pigment {rgb <1,0,0>}}}
>    #declare MinRad = MinRad + 0.0001;
>    #end
> }
>
> object {Test /*rotate x * -90 translate <0,-2,0>*/}
> "Patrick Dugan" <pat### [at] netinsnet> wrote in message
> news:3c5dddaf$1@news.povray.org...
> > Well I probably butchered the formula but here is what I made:
>
>
>

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Shay wrote:
> 
> I'm sorry. 3*pi/4 should have been 3*pi/2
> You don't need to translate the spiral any along the y-axis. Setting x and y
> to the cos and sin of the angle will do that for you.
> The formula itself zill make a half-moon arc. Rotating each sphere some will
> give you the twist.
> Like this:
> #declare MinRad = pi/2;
> #declare MaxRad = (3*pi/2);
> #declare Test =
> union {
>    #while (MinRad < MaxRad)
>       object {sphere {<0,0,0>, 0.01 translate <cos(MinRad)*1, sin(MinRad)*1,
> 0> rotate y*degrees(MinRad)*20 pigment {rgb <1,0,0>}}}
>    #declare MinRad = MinRad + 0.0001;
>    #end
> }
> 
> object {Test /*rotate x * -90 translate <0,-2,0>*/}
> 
> #declare MinRad = pi/2;
> #declare MaxRad = (3*pi/2);
> #declare Test =
> union {
>    #while (MinRad < MaxRad)
>       object {sphere {<0,0,0>, 0.01 translate <cos(MinRad)*1, sin(MinRad)*1,
> 0> rotate y*degrees(MinRad)*20 pigment {rgb <1,0,0>}}}
>    #declare MinRad = MinRad + 0.0001;
>    #end
> }


Also try this:


#declare SphereRadius = 1.5;
#declare SpiralRadius = 0.05;
#declare NrOfTurns = 5;
#declare NrOfSpheres = 1000;

#declare dAngle = 180/NrOfSpheres;

#declare SphereSpiral =
union {
  #declare Cnt = 0;
  #while (Cnt < NrOfSpheres)
    sphere {
      -SphereRadius*y, SpiralRadius
      rotate Cnt*dAngle*<1, 2*NrOfTurns, 0>
    }
    #declare Cnt = Cnt + 1;
  #end // while
}

object {
  SphereSpiral
  pigment { color rgb <1, 1, 1> }
}

light_source { <-2, 2, -3>*10 color rgb <1, 1, 1> }

camera {
  location <0, 1, -2>*2
  look_at <0, 0, 0>
}


Tor Olav

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