private (float, Vector2) _AreaCentroid( )
{
Vector2 centroid = Vector2.Zero;
float area = 0.0f;
for (int i = 1; i < OuterPoints.Length - 1; i++)
{
int i0 = 0;
int i1 = 1;
int i2 = i + 1;
Vector2 v0 = OuterPoints[i0];
Vector2 v1 = OuterPoints[i1];
Vector2 v2 = OuterPoints[i2];
Vector2 cenTri = (v0 + v1 + v2) / 3.0f;
float areaTri = 0.5f * FloatMath.Fabs(Vector2.Dot(v1 - v0, (v2 - v0).PerpLeft));
area += areaTri;
centroid += cenTri * areaTri;
}
centroid /= area;
return(area, centroid);
}
public static FindLineLineResult Intersect(Line line0, Line line1)
{
FindLineLineResult lineLineResult = new FindLineLineResult();
Vector2 diff = line1.Origin - line0.Origin;
float D0DotPerpD1 = Vector2.Dot(line0.Direction.PerpLeft, line1.Direction);
if (D0DotPerpD1 != 0.0f)
{
// The lines are not parallel.
lineLineResult.Intersect = true;
lineLineResult.NumIntersections = 1;
float invD0DotPerpD1 = 1.0f / D0DotPerpD1;
float diffDotPerpD0 = Vector2.Dot(diff.PerpLeft, line0.Direction);
float diffDotPerpD1 = Vector2.Dot(diff.PerpLeft, line1.Direction);
float s0 = diffDotPerpD1 * invD0DotPerpD1;
float s1 = diffDotPerpD0 * invD0DotPerpD1;
lineLineResult.Line0Parameter = s0;
lineLineResult.Line1Parameter = s1;
lineLineResult.Point = line0.Origin + s0 * line0.Direction;
}
else
{
// The lines are parallel.
diff.Normalize();
float diffNDotPerpD1 = Vector2.Dot(diff.PerpLeft, line1.Direction);
if (FloatMath.Fabs(diffNDotPerpD1) != 0.0f)
{
// The lines are parallel but distinct.
lineLineResult.Intersect = false;
lineLineResult.NumIntersections = 0;
}
else
{
// The lines are the same.
lineLineResult.Intersect = true;
lineLineResult.NumIntersections = Int32.MaxValue;
float maxfloat = float.MaxValue;
lineLineResult.Line0Parameter = maxfloat;
lineLineResult.Line1Parameter = maxfloat;
}
}
return(lineLineResult);
}