Is this the right group to discuss details of an object in the collection?

If so,
I wanted to discuss how to improve, or add another scroll object.
I am referring to   Scroll    Version: chrisb 1.0

It is not built along an axis and is therefore not easy to place and
to orient it. Also, I would like to use it as a scroll, with text (or pictures)
but am having poor results with text.

I was rewriting it to use some conventions that would allow several parameters
but my goal of having text was lost when the straight portion is smooth.

Leef_me

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> Is this the right group to discuss details of an object in the collection?

Well, the group is otherwise mostly quiet anyway, so I don't think it's 
wrong to discuss that here.

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"Leef_me" <nomail@nomail> wrote in message 
news:web.4730e948c70624052a7b15450@news.povray.org...
> Is this the right group to discuss details of an object in the collection?


Yes, it's absolutely fine to discuss it here.

>
> If so,
> I wanted to discuss how to improve, or add another scroll object.
> I am referring to   Scroll    Version: chrisb 1.0
>

When submitting another object you have the choice of adding a new object or 
superceding an existing one.

If your object does most or all of what the existing one does, plus other 
stuff that the existing one doesn't (e.g. options for adding text or 
pictures) then choose the 'Existing' option in the first pull-down on the 
submissions screen and use the name 'Scroll'.
Your object will then be displayed in the search screen. The person 
searching for objects will see a pull-down list of versions and will have 
the option of switching to an older version, but the most recent will be 
displayed by default.

If the existing object can be used in ways that your new object can't then 
you should pick a different name, so that both come up when someone does a 
search.

> It is not built along an axis and is therefore not easy to place and
> to orient it. Also, I would like to use it as a scroll, with text (or 
> pictures)
> but am having poor results with text.
>
> I was rewriting it to use some conventions that would allow several 
> parameters
> but my goal of having text was lost when the straight portion is smooth.

I didn't quite understand the last bit of that last sentence.

>
> Leef_me
>

Regards,
Chris B.

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"Chris B" <nom### [at] nomailcom> wrote:
> "Leef_me" <nomail@nomail> wrote in message
> news:web.4730e948c70624052a7b15450@news.povray.org...
> > Is this the right group to discuss details of an object in the collection?
>
>
> Yes, it's absolutely fine to discuss it here.
>
> >
> > If so,
> > I wanted to discuss how to improve, or add another scroll object.
> > I am referring to   Scroll    Version: chrisb 1.0
> >
>
----8<----------8<----------8<----------8<----------8<------
> > I was rewriting it to use some conventions that would allow several
> > parameters
> > but my goal of having text was lost when the straight portion is smooth.
>
> I didn't quite understand the last bit of that last sentence.
>
> >
> > Leef_me
> >
>
> Regards,
> Chris B.


Yeah, I have trouble understanding it too. ;)

I looked at the code for scroll and wanted to "standardize" it.

I wanted to create a version that would allow for user to vary parameters such
as height and width, # of spirals, othe stuff.

I wanted to be able to add text or image to the scroll. For example, "the King
proclaims, thus ..."

I was able to simplify the code for the above ideas.

I was able to add text to the mesh2 object and it looked pretty good.
But, when I tried to smooth the 'straight' portion of the scroll, the text would
either:

show on both sides,
not show at all,


I've tried learning about UV-mapping, but I'm still lost.
My last few posts have been trying to understand what I'm doing wrong.

I'll try later or tomorrow to post a simple version of the code.

Leef_me

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Here's my reworked scroll code. I wanted to focus on determining and
understanding why I get the text on both sides of the scroll and why the weird
pattern appears on the flat portion of the scroll.

+kff10 will rotate the camera so you can see both sides of the scroll.

Thanks in advance to all who can help me understand what's going wrong, and how
to fix this.

     You will need the include file from "Scroll    Version: chrisb 1.0"
     look here       http://lib.povray.org/searchcollection/index.php

Leef_me


#include "colors.inc"
#include "math.inc"
#include "Scroll_array2mesh2.inc"


camera {
      perspective
      location <-0.2,0.3,-2> look_at 0.1
      rotate y*-30
      //rotate y*-30
//      rotate y*-30
      rotate y*90*clock
      translate y*-.5
}

light_source { <-10,4,-4> color rgb 1}
light_source { <0,4,-5> color rgb 1}

light_source { <10,-7,-10> color rgb 1}

light_source { <5,0,-5> color rgb 1}

light_source {   <-.5,0,0> color White   }
light_source {   <.5,0,0> color White    }


#local SW2 =  .80;        // Scroll_width

#local Scroll_R = 0.1015;

#local Scroll_I = -540;
#local Scroll_X = Scroll_R*cosd(Scroll_I);
#local Scroll_Y = Scroll_R*sind(Scroll_I);
#local Scroll_Z = 0;


// The coordinates of the mesh2 nodes are written into an array
#local Scroll_Array = array [1000][2];

// First do a spiral at one end
#local Scroll_I = -540;
#local Scroll_I = 200;      // set start and ending degrees same to disable
spiral
#local Scroll_ArrayIndex = 0;
#local Scroll_R = 0.05;


#while (Scroll_I<200)
  #local Scroll_X = Scroll_R*cosd(Scroll_I);
  #local Scroll_Y = Scroll_R*sind(Scroll_I);
  #local Scroll_Z = 0;
  #local Scroll_Array[Scroll_ArrayIndex][0] =
<Scroll_X,Scroll_Y+0.3,Scroll_Z-SW2>;
  #local Scroll_Array[Scroll_ArrayIndex][1] =
<Scroll_X,Scroll_Y+0.3,Scroll_Z+SW2>;
  #local Scroll_R = Scroll_R*1.01;     // Add 1 percent to the radius each time
  #local Scroll_I = Scroll_I + 10;
  #local Scroll_ArrayIndex = Scroll_ArrayIndex + 1;
#end


#local Scroll_flt = .3;           // this is the flat area of the scroll
#while (Scroll_flt>-.8)

  #local Scroll_Array[Scroll_ArrayIndex][0] =
<Scroll_X,Scroll_Y+Scroll_flt,Scroll_Z-SW2>;
  #local Scroll_Array[Scroll_ArrayIndex][1] =
<Scroll_X,Scroll_Y+Scroll_flt,Scroll_Z+SW2>;

  #local Scroll_ArrayIndex = Scroll_ArrayIndex + 1;
  #local Scroll_flt = Scroll_flt-.02;

#end

// Then add a spiral at the other end
//#local Scroll_I = Scroll_I-10;
#local Scroll_I1 = Scroll_I+720;
#local Scroll_I1 = Scroll_I+0;
                    // set start and ending degrees same to disable spiral
#while (Scroll_I<Scroll_I1)
  #local Scroll_X = Scroll_R*cosd(Scroll_I);
  #local Scroll_Y = Scroll_R*sind(Scroll_I);
  #local Scroll_Z = 0;
  #local Scroll_Array[Scroll_ArrayIndex][0] =
<Scroll_X,Scroll_Y+Scroll_flt,Scroll_Z-SW2>;
  #local Scroll_Array[Scroll_ArrayIndex][1] =
<Scroll_X,Scroll_Y+Scroll_flt,Scroll_Z+SW2>;
  #local Scroll_R = Scroll_R*0.99;
                     // Remove 1 percent from the radius each time
  #local Scroll_I = Scroll_I + 10;
  #local Scroll_ArrayIndex = Scroll_ArrayIndex + 1;
#end


#declare my_text=
text{
  ttf"arialbd.ttf"      "This is a test"    1,0

  translate -z/2
       // suggested by fellow pover Samuel Benge  Date: 21 Oct 2007 20:39:07
       // Re: Simple 2D text on a cylinder's surface
  scale .2
  //rotate <0,0,90>

                 // translation allows placement of text on the surface

//  translate<-.7,0,0>
            // when the rotation is 90, then these parameters are y,x,z
}
            // when the rotation is 0, then these parameters are x,y,z


#if(1)

// Call a function to generate a mesh2 object from the array
#local Scroll_DummyArray  = array [Scroll_ArrayIndex][2];
#local Scroll_Verbose = 0;

object {Scroll_Mesh2FromArray(Scroll_Array, Scroll_DummyArray,
Scroll_ArrayIndex, 2, 0)

    uv_mapping
      texture {                     // one side has background and text

#if(0)

  pigment { color rgb Pink }

#else

      pigment{
        pigment_pattern{
          object{my_text 0,1}
          }
        pigment_map{
            [0 color Yellow]
            [1 color Blue]
        }
      }
#end
    }
    interior_texture {             // the other side has another background
#if(1)

  pigment { color rgb Pink }

#else

      pigment{
        pigment_pattern{
          object{my_text 0,1}
          }
        pigment_map{
            [0 color Red]
            [1 color White]
        }
      }
#end
    }
    rotate y*-45
    rotate y*180*clock             // look at both sides of the disc
}


#end


sky_sphere {
  pigment {
    gradient y
    color_map {
      [0.0 rgb <0.6,0.7,1.0>]
      [0.7 rgb <0.0,0.1,0.8>]
    }
  }
}

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"Leef_me" <nomail@nomail> wrote in message 
news:web.4732b8c8e76f755f892adb1d0@news.povray.org...
>
> Here's my reworked scroll code. I wanted to focus on determining and
> understanding why I get the text on both sides of the scroll and why the 
> weird
> pattern appears on the flat portion of the scroll.
>
>     You will need the include file from "Scroll    Version: chrisb 1.0"
>     look here       http://lib.povray.org/searchcollection/index.php
>
> Leef_me
>

Hi,
The problem is in the macro inside the "Scroll_array2mesh2.inc" file which 
defines the triangles that make up the mesh object. Alternating triangles 
are defined clockwise then anticlockwise causing the normals for each 
triangle to point in the opposite direction to the previous triangle. So on 
each side of the surface, half the area is 'interior' and half is 
'exterior'.

To fix this, replace the 3 identical lines 123, 136 and 149 with copies of 
the following line

          <Scroll_J+1+(Scroll_I+1)*Scroll_JTotal, 
Scroll_J+1+Scroll_I*Scroll_JTotal, Scroll_J+(Scroll_I+1)*Scroll_JTotal>

This just changes the sequence of every second set of triangles so that both 
sets are defined in the same direction, giving it a consistent 'interior' 
and 'exterior'.

Regards,
Chris B.

Post a reply to this message

> To fix this, replace the 3 identical lines 123, 136 and 149 with copies of
> the following line
>
>           <Scroll_J+1+(Scroll_I+1)*Scroll_JTotal,
> Scroll_J+1+Scroll_I*Scroll_JTotal, Scroll_J+(Scroll_I+1)*Scroll_JTotal>
>
> This just changes the sequence of every second set of triangles so that both
> sets are defined in the same direction, giving it a consistent 'interior'
> and 'exterior'.
>
> Regards,
> Chris B.

Yep, that seems to fix the problem. Thanks.

Leef_me

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Chris B escribió:
> "Leef_me" <nomail@nomail> wrote in message 
> news:web.4730e948c70624052a7b15450@news.povray.org...
>> Is this the right group to discuss details of an object in the collection?
> 
> 
> Yes, it's absolutely fine to discuss it here.

The readme file downloaded in a zip mentions (and links to) 
povray.objects newsgroup, which doesn't exist.

Post a reply to this message

"Nicolas Alvarez" <nic### [at] gmailisthebestcom> wrote in message 
news:47dc26d5$1@news.povray.org...

>> "Leef_me" <nomail@nomail> wrote in message 
>> news:web.4730e948c70624052a7b15450@news.povray.org...
>>> Is this the right group to discuss details of an object in the 
>>> collection?
>>
>>
>> Yes, it's absolutely fine to discuss it here.
>
> The readme file downloaded in a zip mentions (and links to) povray.objects 
> newsgroup, which doesn't exist.

ok. Thanks. I've fixed that now to point to this newsgroup.

Regards,
Chris B.

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It's taken a while, but I've removed the limitations reported earlier this 
year with the Scroll object. V2.0 at 
http://lib.povray.org/collection/scroll/chrisb%202.0/scroll.html is now a 
macro with settings that enable you to control almost everything (width. 
length radius etc.).

The uv-mapping and normal issues are sorted, so you can add text or any 
other pattern (including a tiled image map) and have it follow the scroll 
contours. You can specify a seperate interior_texture to get a different 
texture on the back. There's are text layout options for justification of 
blocks of text, including full justification.

Examples are now included demonstrating how to use it for kitchen rolls, 
rolls of wallpaper and tin-foil as well as paper scrolls with writing in 
both portrait and landscape mode. There's even an animation example.

Regards,
Chris B

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