Is it possible to define a reusable object in Povray similar to how it is
done in a programming language? Here is a simple scene.

#version 3.6;

#include "colors.inc"
#include "metals.inc"
#include "glass.inc"
#include "stones.inc"

global_settings {
  assumed_gamma 1.0
}

// ----------------------------------------

camera {
  location  <5.0, 80.0, 5.0>
  direction 1.5*z
  right     x*image_width/image_height
  look_at   <0.0, 0.0,  0.0>
}

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>]
    }
  }
}

light_source {
  <0, 0, 0>            // light's position (translated below)
  color rgb <1, 1, 1>  // light's color
  translate <-30, 30, -30>
}

// ----------------------------------------

plane {
  y, -1
  pigment { color rgb <0.5, 0.5, 0.5> }
}

#declare RADIUS = 1.3;
#declare BACKGROUND = T_Stone11;
#declare TITLE = color Yellow;
#declare ZMIN = -7.5;

//box { <-2, -0.5, -2.5>, <4, 0.5, -7.5> texture{BACKGROUND} }  // 10
//box { <-4, -0.5, -2.5>, <-2, 0.5, -7.5> pigment{TITLE} }
//cylinder { <-4, 0.5, -2.5>, <4, 0.5, -2.5>, 0.01 pigment{color Black}}

//box { <-2, -0.5, -2.5>, <4, 0.5, 2.5> texture{BACKGROUND} }  // 10
//box { <-4, -0.5, -2.5>, <-2, 0.5, 2.5> texture{T_Stone11} }
//cylinder { <-4, 0.5, 2.5>, <4, 0.5, 2.5>, 0.01 pigment{color Black}}

//box { <-2, -0.5, 2.5>, <4, 0.5, 7.5> texture{BACKGROUND} }  // 10
//box { <-4, -0.5, 2.5>, <-2, 0.5, 7.5> pigment{TITLE} }
//cylinder { <-4, 0.5, 7.5>, <4, 0.5, 7.5>, 0.01 pigment{color Black}}

#declare BLOCK = union
        {
        box { <-2, -0.5, ZMIN>, <4, 0.5, (ZMIN + 5)> texture{BACKGROUND} }
// 10
        box { <-4, -0.5, ZMIN>, <-2, 0.5, ZMIN + 5> pigment{TITLE} }
        cylinder { <-4, 0.5, ZMIN>, <4, 0.5, ZMIN>, 0.01 pigment{color
Black}}
        //#declare ZMIN = ZMIN+5;
        }

BLOCK
#declare TITLE = color Red;
#declare ZMIN = ZMIN + 5;
sphere { <0, 0, ZMIN>, RADIUS pigment{TITLE}}
object{ BLOCK translate <0, 0, ZMIN> }

#declare TITLE = color Green;
#declare ZMIN = ZMIN + 5;
sphere { <0, 0, ZMIN>, RADIUS pigment{TITLE}}
object{ BLOCK translate <0, 0, ZMIN> }

#declare TITLE = color Blue;
#declare ZMIN = ZMIN + 5;
sphere { <0, 0, ZMIN>, RADIUS pigment{TITLE}}
object{ BLOCK translate <0, 0, ZMIN> }

The commented sections are what I would like to produce (with a little more
frills) The bottom section is the object declaration and how I would like to
use it to produce the same. The sphere's are purely diagnostic and given
that they work I can conclude that the BLOCK object is parsed only once at
declaration. Thereafter it doesn't matter what ZMIN or TITLE are changed to.
Hence it does not work. However if sphere and other basic shapes can be
defined like this can I not declare(?) or describe and use BLOCK with
replaceable parameters as well. Hope somebody can help as I get the distinct
idea I have missed something very fundamental and this is a really dumb
question.

Many thanks

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If I'm understanding correctly you want to use #macro BLOCK() ...blah... 
#end, instead of #declare. #declared things get parsed when the code is 
encountered, #macros get parsed every time they're used, exactly like a 
procedural scripting language :)

-- 
Tek
http://evilsuperbrain.com

"David Instone" <d.i### [at] gmailcom> wrote in message 
news:45800f7c@news.povray.org...
> Is it possible to define a reusable object in Povray similar to how it is
> done in a programming language? Here is a simple scene.
>
> #version 3.6;
>
> #include "colors.inc"
> #include "metals.inc"
> #include "glass.inc"
> #include "stones.inc"
>
> global_settings {
>  assumed_gamma 1.0
> }
>
> // ----------------------------------------
>
> camera {
>  location  <5.0, 80.0, 5.0>
>  direction 1.5*z
>  right     x*image_width/image_height
>  look_at   <0.0, 0.0,  0.0>
> }
>
> 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>]
>    }
>  }
> }
>
> light_source {
>  <0, 0, 0>            // light's position (translated below)
>  color rgb <1, 1, 1>  // light's color
>  translate <-30, 30, -30>
> }
>
> // ----------------------------------------
>
> plane {
>  y, -1
>  pigment { color rgb <0.5, 0.5, 0.5> }
> }
>
> #declare RADIUS = 1.3;
> #declare BACKGROUND = T_Stone11;
> #declare TITLE = color Yellow;
> #declare ZMIN = -7.5;
>
> //box { <-2, -0.5, -2.5>, <4, 0.5, -7.5> texture{BACKGROUND} }  // 10
> //box { <-4, -0.5, -2.5>, <-2, 0.5, -7.5> pigment{TITLE} }
> //cylinder { <-4, 0.5, -2.5>, <4, 0.5, -2.5>, 0.01 pigment{color Black}}
>
> //box { <-2, -0.5, -2.5>, <4, 0.5, 2.5> texture{BACKGROUND} }  // 10
> //box { <-4, -0.5, -2.5>, <-2, 0.5, 2.5> texture{T_Stone11} }
> //cylinder { <-4, 0.5, 2.5>, <4, 0.5, 2.5>, 0.01 pigment{color Black}}
>
> //box { <-2, -0.5, 2.5>, <4, 0.5, 7.5> texture{BACKGROUND} }  // 10
> //box { <-4, -0.5, 2.5>, <-2, 0.5, 7.5> pigment{TITLE} }
> //cylinder { <-4, 0.5, 7.5>, <4, 0.5, 7.5>, 0.01 pigment{color Black}}
>
> #declare BLOCK = union
>        {
>        box { <-2, -0.5, ZMIN>, <4, 0.5, (ZMIN + 5)> texture{BACKGROUND} }
> // 10
>        box { <-4, -0.5, ZMIN>, <-2, 0.5, ZMIN + 5> pigment{TITLE} }
>        cylinder { <-4, 0.5, ZMIN>, <4, 0.5, ZMIN>, 0.01 pigment{color
> Black}}
>        //#declare ZMIN = ZMIN+5;
>        }
>
> BLOCK
> #declare TITLE = color Red;
> #declare ZMIN = ZMIN + 5;
> sphere { <0, 0, ZMIN>, RADIUS pigment{TITLE}}
> object{ BLOCK translate <0, 0, ZMIN> }
>
> #declare TITLE = color Green;
> #declare ZMIN = ZMIN + 5;
> sphere { <0, 0, ZMIN>, RADIUS pigment{TITLE}}
> object{ BLOCK translate <0, 0, ZMIN> }
>
> #declare TITLE = color Blue;
> #declare ZMIN = ZMIN + 5;
> sphere { <0, 0, ZMIN>, RADIUS pigment{TITLE}}
> object{ BLOCK translate <0, 0, ZMIN> }
>
> The commented sections are what I would like to produce (with a little 
> more
> frills) The bottom section is the object declaration and how I would like 
> to
> use it to produce the same. The sphere's are purely diagnostic and given
> that they work I can conclude that the BLOCK object is parsed only once at
> declaration. Thereafter it doesn't matter what ZMIN or TITLE are changed 
> to.
> Hence it does not work. However if sphere and other basic shapes can be
> defined like this can I not declare(?) or describe and use BLOCK with
> replaceable parameters as well. Hope somebody can help as I get the 
> distinct
> idea I have missed something very fundamental and this is a really dumb
> question.
>
> Many thanks
>
>

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