Distance

        9        
       98889      
     988777889    
    88776667788   
   8776655566778  
   8765544455678  
  876544333445678 
  876543222345678 
 87654321112345678
 87654321@12345678
 87654321112345678
  876543222345678 
  876544333445678 
   8765544455678  
   8776655566778  
    88776667788   
     988777889    
       98889      
         9        

0.9.9.5 and Below

Sight is measured the same, but with a +1 radius.

0.9.9.6

Sight radius has been dropped by -1 in order to balance the glow/rendered light of the graphical tiles.

Distance in DRL is measured according to the so-called Angband metric. In short, distance is the long axis plus half the short axis. The result is always rounded down.

The Angband metric is intended to approximate the usual Euclidean metric. If we round the Euclidean metric to the nearest integer, then the comparison is as follows. Up to a radius of 3, the metrics coincide exactly. Up to a radius of 11, the difference is within 1. In general (ignoring rounding), the Angband metric is always greater than the Euclidean metric, but not more than 12% greater.