functions in drat.i - R

 Ray_Path  
 
struct Ray_Path {  
  pointer zone;   /* list of zones (1-origin) cut by the ray */  
  pointer ds;     /* list of path lengths in above zones */  
  double fi, ff;  /* fraction of 1st and last ds, respectively, outside  
		     the specified slimits */  
  pointer pt1, pt2;  /* lists of endpoints of edges cut by ray -- ray cuts  
		        directed edge pt1->pt2 from right to left  
			Like zone, always 1-origin values.  */  
  pointer f;         /* list of fractions -- (f+0.5) is the fraction of  
			distance from pt1 to pt2 where ray cuts edge */  
}  

structure, defined at i0/drat.i   line 1232