POV-Ray : Newsgroups : povray.general : Tied in Knots (Twisting objects) Server Time
31 Jul 2024 10:23:20 EDT (-0400)
  Tied in Knots (Twisting objects) (Message 1 to 2 of 2)  
From: Arch Angel
Subject: Tied in Knots (Twisting objects)
Date: 22 Jun 2007 17:45:01
Message: <web.467c41ba5d84847d3ae44dcf0@news.povray.org>
Well more like I wish I were in knots.  I'm working on what I thought
 to be a relatively simple architecture scene, when the problem I have
 with drawing in real live hit the digits hard.

  Here is my base so far


  prism{
    linear_sweep // or conic_sweep for tapering to a point
    linear_spine  //linear_spline | quadradic_spline | cubic_spline |
 bezier_spline
   //note-I thought about changing this.  Would that help
  -0.0,   // height 1
  35.0,  // height 2
  3,  // number of points
  // (----the <u,v> points---)
  <-3,1.6666666667>,<3,1.6666666667>,<0,-3.3333333333>
  //objective: cause rotation along the vertical
  //axis so that the point on base twist
  //around "tower" by little more than one complete turn.
  //Twist                note-derived from help menu
  //  twist n turns/unit around x
  //replace "y" with "z*sin(x*2*pi*N)+y*cos(x*2*pi*N)"
  //replace "z" with "z*cos(x*2*pi*N)-y*sin(x*2*pi*N)"
  //am I suppose to use rotate command? N=?
  //what does this look like?
  texture {T_Chrome_1B}}
  //Still to come giving the "tower's" sides a concave curve(carve)
  //from top to bottom on all sides.    AAAAAAAAAAAAAAHHHHHHHHH!!!!!

Please e-mail me with any help you can pro### [at] bluearch_ang### [at] yahoocom.


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From: Alain
Subject: Re: Tied in Knots (Twisting objects)
Date: 23 Jun 2007 20:14:19
Message: <467DB75E.2070505@netscape.net>
Arch Angel nous apporta ses lumieres en ce 2007/06/22 17:41:
> Well more like I wish I were in knots.  I'm working on what I thought
>  to be a relatively simple architecture scene, when the problem I have
>  with drawing in real live hit the digits hard.
> 
>   Here is my base so far
> 
> 
>   prism{
>     linear_sweep // or conic_sweep for tapering to a point
>     linear_spine  //linear_spline | quadradic_spline | cubic_spline |
>  bezier_spline
>    //note-I thought about changing this.  Would that help
>   -0.0,   // height 1
>   35.0,  // height 2
>   3,  // number of points
>   // (----the <u,v> points---)
>   <-3,1.6666666667>,<3,1.6666666667>,<0,-3.3333333333>
>   //objective: cause rotation along the vertical
>   //axis so that the point on base twist
>   //around "tower" by little more than one complete turn.
>   //Twist                note-derived from help menu
>   //  twist n turns/unit around x
>   //replace "y" with "z*sin(x*2*pi*N)+y*cos(x*2*pi*N)"
>   //replace "z" with "z*cos(x*2*pi*N)-y*sin(x*2*pi*N)"
>   //am I suppose to use rotate command? N=?
>   //what does this look like?
>   texture {T_Chrome_1B}}
>   //Still to come giving the "tower's" sides a concave curve(carve)
>   //from top to bottom on all sides.    AAAAAAAAAAAAAAHHHHHHHHH!!!!!
> 
> Please e-mail me with any help you can pro### [at] bluearch_ang### [at] yahoocom.
> 
>
A linear_spline prism always have flat faces, any rotation will affect it as a 
whole. Also, a matrix transform will never bend nor warp any surface: any 3 
colinear points will always stay colinear no mather what transform you apply to 
your object.
In the case of your twisted prism, you need to use one of the following:
  - A mesh object
OR
  - An isosurface where you can use your equation to cause a rotation acording 
to the x position.

Both solution are still viable if you want to make curved faces, concave or 
convex make no difference, you only need to change the sign.

-- 
Alain
-------------------------------------------------
A wise and frugal government, which shall leave men free to regulate their
own pursuits of industry and improvement, and shall not take from the mouth
of labor and bread it has earned - this is the sum of good government.
Thomas Jefferson


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