Vector2 GetCentroid(this ShapeData someShape)
{
float AFactor = 1.0f / (6 * someShape.GetArea());
float xSum = 0;
float ySum = 0;
for (int i = 0; i < someShape.Points.Count - 1; ++i)
{
float part = ShapeDataExtension.AreaSumPart(
someShape.Points[i].X * someShape.Size,
someShape.Points[i + 1].Y * someShape.Size,
someShape.Points[i + 1].X * someShape.Size,
someShape.Points[i].Y * someShape.Size
);
xSum +=
(someShape.Points[i].X * someShape.Size
+ someShape.Points[i + 1].X * someShape.Size)
* part;
ySum +=
(someShape.Points[i].Y * someShape.Size
+ someShape.Points[i + 1].Y * someShape.Size)
* part;
}
return
(new Vector2(xSum, ySum) * AFactor);
}
float GetArea(this ShapeData someShape)
{
float A = 0;
for (int i = 0; i < someShape.Points.Count - 1; ++i)
{
A += ShapeDataExtension.AreaSumPart(
someShape.Points[i].X * someShape.Size,
someShape.Points[i + 1].Y * someShape.Size,
someShape.Points[i + 1].X * someShape.Size,
someShape.Points[i].Y * someShape.Size
);
}
return(A / 2.0f);
}
