Seasons Greetings !

  The Pov text below describes a closed curve shape
(like a serving tray). I want to use the cubic spline
to help give me smooth curves with a limited amount
of control points. Problem is when I use cubic verses
linear of quadratic the closed curve section of the
shape gets cut out. Would somebody check this out
and tell me if I'm applying this wrong or if it's
just not behaving properly.

Thanks

-- 
 Ken Tyler

 tyl### [at] pacbellnet

-----------------------

  lathe{
  cubic_spline 
  // quadratic_spline
  //linear_spline
  13,
  <0.00, 0.00>,
  <2.00, 0.00>,
  <2.20, 0.10>,
  <2.30, 0.20>,
  <2.30, 0.25>,
  <2.50, 0.26>,
  <2.52, 0.27>,
  <2.30, 0.28>,
  <2.29, 0.27>,
  <2.20, 0.20>,
  <2.10, 0.19>,
  <1.90, 0.18>,
  <0.00, 0.17>
  pigment{rgb .7}
  finish{ambient .4 diffuse .3}}

  camera{location<0,  7, -8> look_at 0 }
  light_source{  <0,100,-33> rgb 1}

Post a reply to this message

Ken wrote:
> 
> Seasons Greetings !
> 
>   The Pov text below describes a closed curve shape
> (like a serving tray). I want to use the cubic spline
> to help give me smooth curves with a limited amount
> of control points. Problem is when I use cubic verses
> linear of quadratic the closed curve section of the
> shape gets cut out. Would somebody check this out
> and tell me if I'm applying this wrong or if it's
> just not behaving properly.
> 
>.....pov-code

Hello Ken,

using cubic_spline povray will take the first and the last of your <u,v>
coordinates as mere control points for the slope of the spline at the
second and the last_but_one coordinate.
So try out something like following, and it will work correctly:

//pov-code:
lathe{
  cubic_spline 
  //quadratic_spline
  //linear_spline
  15,
  <0.00, 0.17>
  <0.00, 0.00>,
  <2.00, 0.00>,
  <2.20, 0.10>,
  <2.30, 0.20>,
  <2.30, 0.25>,
  <2.50, 0.26>,
  <2.52, 0.27>,
  <2.30, 0.28>,
  <2.29, 0.27>,
  <2.20, 0.20>,
  <2.10, 0.19>,
  <1.90, 0.18>,
  <0.00, 0.17>,
  <0.00, 0.00>,
  pigment{rgb .7}
  finish{ambient .4 diffuse .3}}

  camera{location<0,  7, -8> look_at 0 }
  light_source{  <0,100,-33> rgb 1}
//end of pov-code

Merry christmas 
ReVerSi

Post a reply to this message

ReVerSi wrote:
> 
> Hello Ken,
> 
> using cubic_spline povray will take the first and the last of your <u,v>
> coordinates as mere control points for the slope of the spline at the
> second and the last_but_one coordinate.
> 
> 
> Merry christmas
> ReVerSi

Thank You !

-- 
 Ken Tyler

 tyl### [at] pacbellnet

Post a reply to this message