private void setVertex()
{
float xmin = float.MaxValue;
float ymin = float.MaxValue;
float xmax = float.MinValue;
float ymax = float.MinValue;
for (int i = 0; i < 4; i++)
{
xmax = Math.Max(xmax, vertex[i].X);
ymax = Math.Max(ymax, vertex[i].Y);
xmin = Math.Min(xmin, vertex[i].X);
ymin = Math.Min(ymin, vertex[i].Y);
}
rect = new RectInt((int)xmin, (int)ymin, (int)(xmax - xmin), (int)(ymax - ymin));
AB = new Vector(vertex[0], vertex[1]);
BC = new Vector(vertex[1], vertex[2]);
CD = new Vector(vertex[2], vertex[3]);
DA = new Vector(vertex[3], vertex[0]);
// get unit vector
AB /= AB.Magnitude;
BC /= BC.Magnitude;
CD /= CD.Magnitude;
DA /= DA.Magnitude;
}
public static double DistancePointLine(PointF pt, PointF lnA, PointF lnB)
{
Vector v1 = new Vector(lnA, lnB);
Vector v2 = new Vector(lnA, pt);
v1 /= v1.Magnitude;
return Math.Abs(v2.CrossProduct(v1));
}
public static bool IsCCW(PointF pt1, PointF pt2, PointF pt3)
{
Vector V21 = new Vector(pt2, pt1);
Vector v23 = new Vector(pt2, pt3);
return V21.CrossProduct(v23) > 0; // sin(angle pt2 pt1 pt3) < 0, 180<angle pt2 pt1 pt3 <360
}
public static bool IsClockwise(PointF pt1, PointF pt2, PointF pt3)
{
Vector V21 = new Vector(pt2, pt1);
Vector v23 = new Vector(pt2, pt3);
return V21.CrossProduct(v23) < 0; // sin(angle pt1 pt2 pt3) > 0, 0<angle pt1 pt2 pt3 <180
}
// A. B=|A|.|B|.cos(angle AOB)
public double DotProduct(Vector v)
{
return _x * v.X + _y * v.Y;
}
// A * B =|A|.|B|.sin(angle AOB)
public double CrossProduct(Vector v)
{
return _x * v.Y - v.X * _y;
}
