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/* polygon_centroid.c - find the centroid of an arbitrary polygon */

/* includes */
#include <euclid/geometry.h>

/*
 * Given a polygon, calculate its centroid, which is just the simple
 * average of the X coordinates of the vertices and the simple average
 * of the Y coordinates of the vertices.
 */
void
EG_polygon_centroid_i(const Point_i *points, const int n,
		      Point_d *centroid)
{
  double x_sum = 0.0;
  double y_sum = 0.0;
  
  int i;
  
  if (n <= 0)
  {
    centroid->x = 0.0;
    centroid->y = 0.0;
    
    return;
  }
  
  for (i = 0; i < n; ++i)
  {
    x_sum += (double)points[i].x;
    y_sum += (double)points[i].y;
  }
  
  centroid->x = x_sum / (double)n;
  centroid->y = y_sum / (double)n;
}


void
EG_polygon_centroid_d(const Point_d *points, const int n,
		      Point_d *centroid)
{
  double x_sum = 0.0;
  double y_sum = 0.0;
  
  int i;
  
  if (n <= 0)
  {
    centroid->x = 0.0;
    centroid->y = 0.0;
    
    return;
  }
  
  for (i = 0; i < n; ++i)
  {
    x_sum += points[i].x;
    y_sum += points[i].y;
  }
  
  centroid->x = x_sum / (double)n;
  centroid->y = y_sum / (double)n;
}