> Hi,
> 
> I want to have a thin box (or plate) with a lot of equaly spaced holes inside.
> 
> Basically I know how to do it and it already worked, but I needed ~17min to
> render the picture, so I hope there is a better (faster) way to reach my goal.
> 
> 
> Here is what I did:
> 
> ----------------------------------------------------------------------------
> #include "colors.inc"
> #include "textures.inc"
> 
> #declare i=0; //just two counters
> #declare j=0;
> 
> 
> //here follows the box:
> #declare pure_table=box{<0,0,0>, <-362, 1, 150>
>  texture{
>   pigment{color rgb<0.7,0.7,0.7>}
>   normal{wrinkles scale 0.02}
>   finish{phong 1.0 phong_size 120 metallic reflection 0.3 brilliance 2}
>   }
>  };
> 
> //one Hole is defined here:
> #declare hole=sphere{<0,0.5,0>,0.7 pigment{color Black}};
You do this only if you want the sides of the holes to actualy be black. 
Also, it's more effecient to apply any texture to an union rather that 
to each of the components.
> 
> //just a few constants
> #declare hole_xoffset=4.75;
> #declare hole_zoffset=3.75;
> #declare holes_x=141;
> #declare holes_z=57;
> 
> 
> //this is the macro that gives me all the holes I want to have;
> #macro all_holes()
> union{#while(i< holes_x)
>   #while(j<holes_z)
>       object{hole translate <-hole_xoffset-i*2.5,0,hole_zoffset+j*2.5>}
>  #declare j = j + 1;
>       #end
>   #declare j=0;
>   #declare i =i + 1;
> #end
If you want a distinct texture for the holes, add it here.
>    }
> #end
> 
> //here I draw the difference between the table and the holes:
> difference{object{pure_table}
> object{all_holes()}}
> 
> 
> //top-view camea
> camera {
>     location <-180, 90, 75>
>     look_at <-160, 0, 70>
> }
> 
> 
> light_source {
>     <-300, 90, 75>
>     color White
> }
> 
> 
> /*this light source is just the test for me to see, if the holes are really
> through the table*/
> light_source {
>   <-300,-70,75>
>   color Blue
>   }
> 
> plane{<0,1,0>,-100
>       pigment{
>     gradient x
>     color_map{
>         [0.8 rgb<0.9,0.9,0.9>  ]
>         [1.0 rgb<0.5,0.5,0.5>  ]
>               }
>    turbulence 1
>    }
> }
> 
> ---------------------------------------------------------------
> 
> 
> Another thing I tried was not to have the macro but a normal definition
> 
> ---------------
> #declare all_holes=#while ...... #end
> -------------
> 
> My Problem with this solution was, that I alway got error messages from the
> POVRay-Parser when I ended the line with a ";"
> But without the ";" all the spheres were actually drawn which is the complete
> opposite from the thing I want to have.
> Only the rendering time was very short....
> 
> 
> Every advice or comment is appreciated.
> 
> Thanks
> 
> 

Normaly, in that case, the best way is to first declare a small box with 
a single hole.
Then, you assemble many of those small box with a single hole into a 
large composite object.

Things to do and dont do:
Don't apply any texture to your small boxes, nor to the object used to 
make the hole.

Do apply the texture to the complete usion.

Why this is way faster:
When you use a difference where you remove a large number of objects 
from a single one, the bounding becomes VERY ineficient. For each ray 
that can encounter your object, the base object and each and every holes 
must be tested.

When you use many small components in an union, each small box-hole 
component have it's own bounding, and you only have to test very few 
components for each ray. This will save you a conciderable amount of time.

Question of "style": you should always use an opper-case character as 
the first character of any user defined variable.
"x", "y", "z", "t", "clock", "gray", "grey" where once not reserved 
variables names. When they became reserved, it played havok with many 
scenes that used them as user variables...
Who know, "i", "j", "k" may become reserved at some time.



Alain

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