"David Vincent-Jones" <geo### [at] galaxynetcom> wrote:

> Can somebody explain to me why the following code is halting at the second
> read.

As far as I can see, what happens is your second loop reads the last entry
in Build.dat - but it does not close the file, because POV closes the file
when it reads EOF. So the condition of the first while loop is still
satisfied; the loop starts, the first #read reads EOF and closes the file.
After this NB_File is undefined and the second #read gives an error.

Here's a hack that works around the problem; it checks whether NB_File
is still defined after the first #read; if not, it simply runs an empty loop.

#fopen NB_File "Build.dat" read
#while (defined(NB_File))
   #read (NB_File,Num)
   #if(defined(NB_File))
     #read (NB_File,Elev)
     prism{
       linear_sweep linear_spline
       (Elev+5),(Elev+30)
       Num
       #local i=0;
       #while (i<Num)
         #read (NB_File, Vec)
         Vec
         #local i=i+1;
       #end
       pigment {rgb x}
     }
   #end
#end

-- 
Margus Ramst

Personal e-mail: mar### [at] peakeduee
TAG (Team Assistance Group) e-mail: mar### [at] tagpovrayorg
Home page http://www.hot.ee/margusrt

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