/* Point.h 
	2-D point class
  Original code: JM, 12 Oct 97
*/

#ifndef POINT_H
#define POINT_H

#define RAD(x)  (x*3.1415926/180.0)
#define DEG(x)  (x*180.0/3.1415926)
#ifndef M_PI
#define M_PI	3.1415926
#endif

typedef struct point *Point;

Point ConsPoint( double x, double y );
/* Construct points from cartesian pair 
   Pre-cond: none
   Post-cond: returns a valid point or NULL if no memory
*/
Point ConsPointRT( double r, double theta );
/* Construct points from polar representation pair
   Pre-cond: r >= 0
   Post-cond: returns a valid point or NULL if no memory
*/

void DeletePoint( Point p );
/* Delete p and free resources 
   Pre-cond: p != NULL
*/

Point CopyPoint( Point p );
/* Make a copy of point p
   Pre-cond: p != NULL
   Post-cond: returns copy of p or NULL if no memory
*/

void FreePoint( Point p );
/* Synonym for DeletePoint */

void SetPoint( Point p, double x, double y );
/* Set point p to (x,y)
   (enable re-use of structures, saves unnecessary Cons/Delete)
   Pre-cond: p != NULL
   Post-cond: p is set to (x,y)
*/

void SetPoint2( Point p, Point p1 );
/* Set a point .. enables re-use of the structure!
   Pre-cond: (p != NULL) && (p1 != NULL)
   Post-cond: p and p1 are identical
*/

double XCoord( Point p );
double YCoord( Point p );
double RPolar( Point p );
double TPolar( Point p );
/* Projectors 
   Pre-cond: p != NULL 
*/

double Dist( Point p1, Point p2 );
/* Returns distance between p1 and p2
   Pre-cond: (p1 != NULL) && (p2 != NULL)
*/

void Displace( Point p, Point delta );
/* Displace p by delta: p := p+delta
   Pre-cond: (p != NULL) && (delta != NULL)
   Post-cond: p is displaced by delta
*/

double Direction( Point p1, Point p2 );
/* Return the direction from p1 to p2 in radians 
   Pre-cond: (p1 != NULL) && (p2 != NULL)
   Post-cond: return value is in -PI,+PI
*/
double AngleBetween( Point p1, Point p2, Point p3 );

void PrintPoint( char *s, Point p );
#endif