Hello,

please help me!

What is this, and how can I avoid it?

Thanks

--
MfG

Manuel Kasten

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Attachments:
Download 'problem.jpg' (13 KB)

Preview of image 'problem.jpg'

"Manuel Kasten" <kas### [at] gmxde> wrote in message
news:3e457b57@news.povray.org...
> Hello,
>
> please help me!
>
> What is this, and how can I avoid it?

    I used to get those all the time in my phone cords, then I went to Radio
Shack and bought some of those little twisty ends for the cords and I never
had that problem again.


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Manuel Kasten wrote:
> What is this, and how can I avoid it?

That's a kink in your phone cord...to remove it, take the handset and
loop it around once...;)

-- 
--Tim Cook
http://home.bellsouth.net/p/PWP-empyrean

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Never seen that happen before so I couldn't tell you anything. It doesn't
looks like a part of the spline, e.g. a misplaced endpoint/control point.
Looks a lot like a separate piece.

Is this using the spline macro? I suppose there's a chance it could be where
two splines meet...  No way of knowing without checking the pov script.

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"hughes, b." <omn### [at] charternet> schrieb:
> Never seen that happen before so I couldn't tell you anything. It doesn't
> looks like a part of the spline, e.g. a misplaced endpoint/control point.
> Looks a lot like a separate piece.
>
> Is this using the spline macro? I suppose there's a chance it could be where
> two splines meet...  No way of knowing without checking the pov script.
>
>

It is only one spline.

I was able to reproduce it, but that didn't help me to avoid it in my scene.

Here's the reproduce:


----------code----------
#include "spline.mcr"

#declare coil = create_spline (
   array[3] {<-75,0,0><0,0,3><75,0,0>},
   create_default_spline +
   spline_sampling (on) )

#declare coil2 = create_spline (
   array[3] {<0,0,-75><-3,0,0><0,0,75>},
   create_default_spline +
   spline_sampling (on) )

union {coil_spline (coil, spline_steps (40)
   + spline_radius (4)
   + coil_radius (1.5))
   pigment {rgb <1, 0, 0>}
   finish {phong 0.6}
   translate 20*z}

union {coil_spline (coil2, spline_steps (40)
   + spline_radius (4)
   + coil_radius (1.5))
   pigment {rgb <1, 0, 0>}
   finish {phong 0.6}
   rotate 90*y
   translate -20*z}


camera {location  <0,500,-150> look_at <0,0,0> angle 20}
background{rgb 1}
light_source { <500,500,500> rgb 1 }

----------end_code----------

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Attachments:
Download 'problem2.jpg' (24 KB)

Preview of image 'problem2.jpg'

I'm not too familiar with the spline macro so I was hoping someone else,
even Chris Colefax himself, might know of a remedy for this. What it seems
to be is that the coil object (torus spiral) is meeting in a mirrored
fashion instead of compensating for the bend. I looked over the macro quite
a while but I can't see a simple solution. Unless maybe it would be to use a
different object.

Bob

"Manuel Kasten" <kas### [at] gmxde> wrote in message
news:3e46d439@news.povray.org...
>
> Here's the reproduce:
> ----------code----------
> #include "spline.mcr"
>
> #declare coil = create_spline (
>    array[3] {<-75,0,0><0,0,3><75,0,0>},
>    create_default_spline +
>    spline_sampling (on) )
>
> #declare coil2 = create_spline (
>    array[3] {<0,0,-75><-3,0,0><0,0,75>},
>    create_default_spline +
>    spline_sampling (on) )
>
> union {coil_spline (coil, spline_steps (40)
>    + spline_radius (4)
>    + coil_radius (1.5))
>    pigment {rgb <1, 0, 0>}
>    finish {phong 0.6}
>    translate 20*z}
>
> union {coil_spline (coil2, spline_steps (40)
>    + spline_radius (4)
>    + coil_radius (1.5))
>    pigment {rgb <1, 0, 0>}
>    finish {phong 0.6}
>    rotate 90*y
>    translate -20*z}
>
>
> camera {location  <0,500,-150> look_at <0,0,0> angle 20}
> background{rgb 1}
> light_source { <500,500,500> rgb 1 }
>
> ----------end_code----------

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On Sun, 9 Feb 2003 23:23:39 +0100, Manuel Kasten wrote:

> "hughes, b." <omn### [at] charternet> schrieb:
>> Never seen that happen before so I couldn't tell you anything. It doesn't
>> looks like a part of the spline, e.g. a misplaced endpoint/control point.
>> Looks a lot like a separate piece.
>>
>> Is this using the spline macro? I suppose there's a chance it could be where
>> two splines meet...  No way of knowing without checking the pov script.
>>
>>
> 
> It is only one spline.
> 
> I was able to reproduce it, but that didn't help me to avoid it in my scene.
> 
> Here's the reproduce:
> 
> 
> ----------code----------
> #include "spline.mcr"
> 
> #declare coil = create_spline (
>    array[3] {<-75,0,0><0,0,3><75,0,0>},
>    create_default_spline +
>    spline_sampling (on) )
> 
> #declare coil2 = create_spline (
>    array[3] {<0,0,-75><-3,0,0><0,0,75>},
>    create_default_spline +
>    spline_sampling (on) )
> 
> union {coil_spline (coil, spline_steps (40)
>    + spline_radius (4)
>    + coil_radius (1.5))
>    pigment {rgb <1, 0, 0>}
>    finish {phong 0.6}
>    translate 20*z}
> 
> union {coil_spline (coil2, spline_steps (40)
>    + spline_radius (4)
>    + coil_radius (1.5))
>    pigment {rgb <1, 0, 0>}
>    finish {phong 0.6}
>    rotate 90*y
>    translate -20*z}
> 
> 
> camera {location  <0,500,-150> look_at <0,0,0> angle 20}
> background{rgb 1}
> light_source { <500,500,500> rgb 1 }
> 
> ----------end_code----------

I've never used this macro so I'm not sure but it looks like the cable is 
half-turned in one of them creating a quite realistic "kink". I'd guess 
turning one end around would actually help, no joke!
I might be completely wrong...

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Manuel Kasten <kas### [at] gmxde> wrote:
> please help me!
>
> What is this, and how can I avoid it?

The problem you are seeing is caused by the method used to calculate the
normal vector of the spline (required to orient the torus segments used to
create the coil).  The current macro file is hardwired to use a 'sky' vector
of z to calculate the spline normal, and when the spline runs directly along
this axis a shift in orientation occurs.

To fix the problem, you can ensure the spline doesn't run along the z-axis,
or download an updated version of the macro file (from
www.geocities.com/ccolefax/spline), which will allow you to adjust the sky
vector used with the spline_normal_sky option.

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"Chris Colefax" <chr### [at] tagpovrayorg> wrote in message
news:3e4863f5@news.povray.org...
>
> The problem you are seeing is caused by the method used to calculate the
> normal vector of the spline (required to orient the torus segments used to
> create the coil).  The current macro file is hardwired to use a 'sky'
vector
> of z to calculate the spline normal, and when the spline runs directly
along
> this axis a shift in orientation occurs.
>
> To fix the problem, you can ensure the spline doesn't run along the
z-axis,
> or download an updated version of the macro file (from
> www.geocities.com/ccolefax/spline), which will allow you to adjust the sky
> vector used with the spline_normal_sky option.

A big thank you, Chris. As simple an explanation as you make your files seem
(until looking at them!). I was so close to the answer, I tried the
spline_normal_sky once because that was one of the things I thought might
have to do with this (axis shifting) but I obviously used it wrong and saw
no change. Then again, I've now tried the suggested fix and it still isn't
going right. I just redownloaded the spline macro to be sure I have the
right file and retried and it's okay. However, in both files there is a
_SP_normsky which apparently uses y, not z. I won't try to figure it out
since it boggles my mind anyhow.

Bob

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