The Time_Curve Structure

 

Time_Curve only adds three pointers to coordinate functions and information about the time-dependent definition interval and the distribution of the points on the curve to its superclass.  

typedef struct {
  TIME_OBJECT_STRUCT;                   /* Subclass of Time_Object */
  CURVE_PARM *curve_parm;               /* Curve parameter (see below) */
  struct { t_fun *x, *y, *z; } coord_f; /* Coordinate functions */
  } coord_f;
} TIME_CURVE;

The data for curve_parm and coord_f are usually read from a description file with extension *.cv, the functions are read as strings, compiled into a t_fun with the function compiler and evaluated during the computation (refer to section 10.2.8 for a description of the function compiler). The time_parm variables can be used for the functions, see section 8.2.2.1.