"Anthony D. Baye" <Sha### [at] hotmailcom> wrote in message 
news:437f641e$1@news.povray.org...
> Can anybody suggest a method by which a partially unrolled scroll might
> be created Parametrically?  I've been trying to create a CSG scroll, but
> I'm about at my wits' end with the Trig functions.
>
> If anybody can help with this, it would be greatly appreciated.
>
> Regards,
>
> A.D.B

Here's an alternative one:
It uses a different mesh generator (array2mesh2.inc attached) and is less 
parameterised than Mike's. It also rolls the bottom up in the opposite 
direction.


camera {location <-0.2,0.3,-0.5> look_at 0.1}
light_source { <-10,4,-4> color rgb 1}
light_source { <-10,-7,-40> color rgb 1}
#include "math.inc"
#include "array2mesh2.inc"

#local ScrollArray = array [1000][2];

#local I = 0;
#local ArrayIndex = 0;
#local R = 0.015;
#while (I<900)
  #local X = R*cosd(I);
  #local Y = R*sind(I);
  #local Z = 0;
  #local ScrollArray[ArrayIndex][0] = <X+0.15,Y+0.3,Z-0.15>;
  #local ScrollArray[ArrayIndex][1] = <X+0.15,Y+0.3,Z+0.15>;
  #local R = R*1.01;     // Add 1 percent to the radius each time
  #local I = I + 10;
  #local ArrayIndex = ArrayIndex + 1;
#end

#local ScrollArray[ArrayIndex][0] = <X+0.135,Y+0.25,Z-0.15>;
#local ScrollArray[ArrayIndex][1] = <X+0.135,Y+0.25,Z+0.15>;
#local ArrayIndex = ArrayIndex + 1;

#local ScrollArray[ArrayIndex][0] = <X+0.115,Y+0.2,Z-0.15>;
#local ScrollArray[ArrayIndex][1] = <X+0.115,Y+0.2,Z+0.15>;
#local ArrayIndex = ArrayIndex + 1;

#local ScrollArray[ArrayIndex][0] = <X+0.065,Y+0.1,Z-0.15>;
#local ScrollArray[ArrayIndex][1] = <X+0.065,Y+0.1,Z+0.15>;
#local ArrayIndex = ArrayIndex + 1;

#local ScrollArray[ArrayIndex][0] = <X+0.035,Y+0.05,Z-0.15>;
#local ScrollArray[ArrayIndex][1] = <X+0.035,Y+0.05,Z+0.15>;
#local ArrayIndex = ArrayIndex + 1;

#local I = I-40;
#while (I<1800)
  #local X = R*cosd(I);
  #local Y = R*sind(I);
  #local Z = 0;
  #local ScrollArray[ArrayIndex][0] = <X,Y,Z-0.15>;
  #local ScrollArray[ArrayIndex][1] = <X,Y,Z+0.15>;
  #local R = R*0.99;     // Add 1 percent to the radius each time
  #local I = I + 10;
  #local ArrayIndex = ArrayIndex + 1;
#end

#local DummyArray  = array [ArrayIndex][2];
#local ppVerbose = 0;

object {ppMesh2FromArray(ScrollArray, DummyArray, ArrayIndex, 2, 0) pigment 
{color rgb <1,1,0.9>} }

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Attachments:
Download 'array2mesh2.inc.txt' (7 KB)