/* Point.c 
  2-D point
*/

#include <math.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <stdlib.h>

#ifndef PI
#define PI	M_PI
#endif

struct point {
  double x; double y;
  };

#define EPS  1.0e-8
#define ABS(x)  (((x)>=0.0)?(x):(-(x)))

#include "Point.h"

Point ConsPoint( double x, double y ) {
  Point p;
  p = malloc( sizeof( struct point ) );
  if ( p != NULL ) {
    p->x = x;
    p->y = y;
    }
  return p;
  }

Point ConsPointRT( double r, double theta ) {
  Point p;
	assert( r >= 0.0 );
  p = malloc( sizeof( struct point ) );
  if ( p != NULL ) {
    p->x = r*cos( theta );
    p->y = r*sin( theta ); 
    }
  return p;
  }

Point CopyPoint( Point p ) {
  Point p1;
	assert( p != NULL );
  p1 = malloc( sizeof( struct point ) );
  if ( p1 != NULL ) {
    memcpy( p1, p, sizeof( struct point ) );
    }
  return p1;
  }

void DeletePoint( Point p ) {
  assert( p != NULL );
  free( p );
  }

void SetPoint2( Point p, Point p1 ) {
  assert( p != NULL );
  assert( p1 != NULL );
  memcpy( p, p1, sizeof( struct point ) );
  }

void FreePoint( Point p ) {
  assert( p != NULL );
  free( p );
  }

void SetPoint( Point p, double x, double y ) {
  assert( p != NULL );
  p->x = x;
  p->y = y;
  }

double XCoord( Point p ) {
  assert( p != NULL );
  return p->x;
  }

double YCoord( Point p ) {
  assert( p != NULL );
  return p->y;
  }

double RPolar( Point p ) {
  double x, y;
  assert( p != NULL );
  x = p->x; y = p->y;
  return sqrt( x*x + y*y );
  }

double TPolar( Point p ) {
  assert( p != NULL );
  if ( ABS(p->y) < EPS ) {
    return 0.0;
    }
  else {
    if ( ABS(p->x) < EPS ) {
      return M_PI/2.0;
      }
    }  
  return atan2( p->y, p->x );
  }

double Dist( Point p1, Point p2 ) {
  double dx, dy, d;
  assert( p1 != NULL );
  assert( p2 != NULL );
  dx = p1->x - p2->x;
  dy = p1->y - p2->y;
  d = sqrt( dx*dx + dy*dy );
  return d;
  }

void Displace( Point p, Point delta ) {
/* Displace p by delta: p := p+delta */
  assert( p != NULL );
  assert( delta != NULL );
  p->x = p->x + delta->x;
  p->y = p->y + delta->y;
  }
  
/* Direction (radians) from p1 to p2 */
double Direction( Point p1, Point p2 ) {
  double t;
  assert( p1 != NULL );
  assert( p2 != NULL );
  
  t = atan2( p2->y - p1->y, p2->x - p1->x );
  return t;
  }

double AngleBetween( Point p1, Point p2, Point p3 ) {
	double t;
	assert( p1 != NULL );
	assert( p2 != NULL );
	assert( p3 != NULL );

	t = Direction( p2, p1 ) - Direction( p2, p3 );
	if ( t < 0 ) t += (2.0*PI);
	return t;
	}

void PrintPoint ( char *s, Point p ) {
  assert( p != NULL );
  fprintf( stderr, "%s (%6.2f,%6.2f)", s, p->x, p->y ); fflush( stderr );
  }