public BoundingBox(Point[] corners)
{
// compute the fourth point of the rotated rect, pt4 = pt3 - pt2 + p1
this.corners = new Point[4];
for (int i = 0; i < 3; i++)
{
this.corners[i] = corners[i];
}
this.corners[3] = PA.Add(PA.Subtract(corners[2], corners[1]), corners[0]);
// reorder points
this.corners = reOderPoints(this.corners);
this.length = PA.Norm(this.corners[0], this.corners[1]);
this.width = PA.Norm(this.corners[0], this.corners[3]);
this.angle = Math.Atan2(this.corners[1].Y - this.corners[0].Y,
this.corners[1].X - this.corners[0].X) / Math.PI * 180;
this.angle = this.angle > 90 ? this.angle - 180 : this.angle; // (-90, 90]
// compute the center of rotated rect
int xc = 0, yc = 0;
for (int i = 0; i < 4; i++)
{
xc += this.corners[i].X;
yc += this.corners[i].Y;
}
this.center = new Point(xc / 4, yc / 4);
}
public static Point Project2Vector(Point pt1, Point pt2, Point pt3)
{
// project a vector v1 formed by pt1-pt3 into another vector v2 formed by pt1-pt2
Point v1 = PA.Subtract(pt3, pt1);
Point v2 = PA.Subtract(pt2, pt1);
float scale = (float)(PA.Dot(v1, v2) / PA.Norm(v2) / PA.Norm(v2));
PointF projected_pt3 = PA.Add(PA.Multiply(PA.Int2Float(v2), scale), pt1);
return(PA.Float2Int(projected_pt3));
}
public void ShiftCenterTo(Point pt)
{
Point transpt = PA.Subtract(pt, this.center);
for (int i = 0; i < 4; i++)
{
this.corners[i] = PA.Add(this.corners[i], transpt);
}
this.center = pt;
}
public static Point Project2NormalVector(Point pt1, Point pt2, Point pt3)
{
/* project a vector v1 formed by pt1-pt3 into the direction of
* the normal vector of another vector v2 formed by pt1-pt2 */
// compute the unit normal vector of vector v2
Point v2 = PA.Subtract(pt2, pt1);
float magnitude = (float)(PA.Norm(pt1, pt2));
PointF unit_normal = new PointF(v2.Y / magnitude, -v2.X / magnitude);
// project v1 into the normal vector
Point v1 = PA.Subtract(pt3, pt1);
PointF projected = PA.Multiply(unit_normal, (float)PA.Dot(v1, unit_normal));
PointF projected_v3 = PA.Add(projected, pt1);
return(PA.Float2Int(projected_v3));
}
public void ShiftDirection(int ind, int step = 3)
{
// ind = 0 --> move left
// ind = 1 --> move right
// ind = 2 --> move up
// ind = 3 --> move down
Point transpt = new Point(0, 0);
switch (ind)
{
case 0: transpt = new Point(-step, 0); break;
case 1: transpt = new Point(step, 0); break;
case 2: transpt = new Point(0, -step); break;
case 3: transpt = new Point(0, step); break;
}
for (int i = 0; i < 4; i++)
{
this.corners[i] = PA.Add(this.corners[i], transpt);
}
this.center = PA.Add(this.center, transpt);
}