Nikolaj K. Holm wrote:

> I'm quite new in povray, so I tried to search the list for this but without 
> any luck. Here we go..
> 
> I have an object - a sphere - which I want to have repeated at different 
> sizes and at different positions to simulate bubbles in water. I got the 
> water and a single bubble looking the way I want but is there a simpler way 
> to repeat this object making the scale and position changing at random?

Actually, your search could have turned up my recent
sparkling water experiments:

http://news.povray.org/povray.binaries.images/message/%3C45d0d486%40news.povray.org%3E/#%3C45d0d486%40news.povray.org%3E

Here is a snippet of SDL to show how I generated the bubble object
which is to be subtracted from the liquid). Note that all bubbles
form one blob object, which renders a lot faster but is not really
perceptibly different from using individual bubbles.

#declare GLASS_RADIUS   = 0.70;
#declare WATER_LEVEL    = 2.80;
#declare BUBBLE_COUNT   = 600;
#declare BUBBLE_RADIUS  = 0.03;

#declare R = seed(42);

#declare BUBBLE_SHAPE = blob
{
   #local i = 0;
   #while (i < BUBBLE_COUNT)
     #local phi = 2*pi*rand(R);
     #local d   = rand(R) * GLASS_RADIUS;
     #if (d > GLASS_RADIUS)
       #local d = GLASS_RADIUS; /* 50% of bubbles at rim */
     #end
     #local h   = rand(R) * WATER_LEVEL;
     #local r   = 0.5 + 0.5 * rand(R);
     #local r   = r * r * BUBBLE_RADIUS; /* More small bubbles */

     sphere {d*<cos(phi),0,sin(phi)> + h*y,r,1}

     #local i = i + 1;
   #end
   threshold 0.6
}

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