Astronomie francophone

Code : Tout sélectionner

  /// <summary>
  /// Method to compute the centroid of a polygon. This does NOT work for a complex polygon.
  /// </summary>
  /// <param name="poly">points that define the polygon</param>
  /// <returns>centroid point, or PointF.Empty if something wrong</returns>
  public static PointF GetCentroid(List<PointF> poly)
  {
     float accumulatedArea = 0.0f;
     float centerX = 0.0f;
     float centerY = 0.0f;

     for (int i = 0, j = poly.Count - 1; i < poly.Count; j = i++)
     {
        float temp = poly[i].X * poly[j].Y - poly[j].X * poly[i].Y;
        accumulatedArea += temp;
        centerX += (poly[i].X + poly[j].X) * temp;
        centerY += (poly[i].Y + poly[j].Y) * temp;
     }

     if (accumulatedArea < 1E-7f)
        return PointF.Empty;  // Avoid division by zero

     accumulatedArea *= 3f;
     return new PointF(centerX / accumulatedArea, centerY / accumulatedArea);
  }
  

Code : Tout sélectionner

public static Point GetCentroid( Point[ ] nodes, int count )
{
    int x = 0, y = 0, area = 0, k;
    Point a, b = nodes[ count - 1 ];

    for( int i = 0; i < count; i++ )
    {
        a = nodes[ i ];

        k = a.Y * b.X - a.X * b.Y;
        area += k;
        x += ( a.X + b.X ) * k;
        y += ( a.Y + b.Y ) * k;

        b = a;
    }
    area *= 3;

    return ( area == 0 ) ? Point.Empty : new Point( x /= area, y /= area );
}

Code : Tout sélectionner

Image I avec n_r lignes et n_c colones
cent_r, cent_c, sum = 0
for i from 0 to (n_r - 1)
	for j from 0 to (n_c - 1)
		cent_r += î[i,j] * (i + 1)
		cent_c += î[i,j] * (j + 1)
		sum += I[i,j]
cent_r /= sum
cent_c /= sum