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 bool Contains(Point pt)
{
// roate the rectangle angle degree counter-clockwise
Point[] ptsRotated = new Point[4];
Point transpt;
int x, y;
double sin = Math.Sin(angle / 180 * Math.PI);
double cosin = Math.Cos(angle / 180 * Math.PI);
for (int i = 0; i < 4; i++)
{
transpt = PA.Subtract(corners[i], center);
x = Convert.ToInt32(transpt.X * cosin + transpt.Y * sin + center.X);
y = Convert.ToInt32(transpt.X * -sin + transpt.Y * cosin + center.Y);
ptsRotated[i] = new Point(x, y);
}
List <int> xs = ptsRotated.OrderBy(p => p.X).Select(p => p.X).ToList();
List <int> ys = ptsRotated.OrderBy(p => p.Y).Select(p => p.Y).ToList();
//Size size = new Size(Math.Abs(ptsRotated[0].X - ptsRotated[2].X),
// Math.Abs(ptsRotated[0].Y - ptsRotated[2].Y));
Rectangle rect = new Rectangle(xs[0], ys[0], xs[3] - xs[0], ys[3] - ys[0]);
// apply rotation to point p
transpt = new Point(pt.X - center.X, pt.Y - center.Y);
x = Convert.ToInt32(transpt.X * cosin + transpt.Y * sin + center.X);
y = Convert.ToInt32(transpt.X * -sin + transpt.Y * cosin + center.Y);
bool isContained = rect.Contains(new Point(x, y));
return(isContained);
}
public void ShiftCornerTo(int ind, Point pt)
{
if (PA.Norm(pt, corners[ind]) < 1)
{
return;
}
// recompute the coordinates of two adjacent points of this shifted point
Point prjpt1 = PA.Project2Vector(corners[(ind + 2) % 4], corners[(ind + 1) % 4], pt);
Point prjpt2 = PA.Project2Vector(corners[(ind + 2) % 4], corners[(ind + 3) % 4], pt);
// rectify projected pt2/pt1 make sure two vectors formed by these three points are well orthogonal
prjpt2 = PA.Project2NormalVector(corners[(ind + 2) % 4], prjpt1, prjpt2);
this.corners[(ind + 1) % 4] = prjpt1;
this.corners[(ind + 3) % 4] = prjpt2;
// update the shifted point itself
this.corners[ind] = pt;
// reorder
this.corners = reOderPoints(this.corners);
// update width, length
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]
// update the center of new 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 BoundingBox(Point[] corners, double angle)
{
this.corners = new Point[4];
for (int i = 0; i < 4; i++)
{
this.corners[i] = corners[i];
}
this.angle = angle;
// the longer axis is length
this.length = PA.Norm(corners[0], corners[1]);
this.width = PA.Norm(corners[0], corners[3]);
// 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);
}
private Point[] reOderPoints(Point[] pts)
{
Point[] ordered_pts = new Point[4];
int ind = 0;
var inds = pts.Select((pt, i) => new KeyValuePair <int, int>(i, pt.Y))
.OrderBy(x => x.Value).Select(x => x.Key).ToArray();
if ((pts[inds[0]].Y == pts[inds[1]].Y) && (pts[inds[0]].X > pts[inds[1]].X))
{
ind = inds[1];
}
else
{
ind = inds[0];
}
double dis1 = PA.Norm(pts[ind], pts[(ind + 1) % 4]);
double dis2 = PA.Norm(pts[ind], pts[(ind + 3) % 4]);
ordered_pts[1] = dis1 >= dis2 ? pts[(ind + 1) % 4] : pts[(ind + 3) % 4];
ordered_pts[3] = dis1 < dis2 ? pts[(ind + 1) % 4] : pts[(ind + 3) % 4];
ordered_pts[0] = pts[ind];
ordered_pts[2] = pts[(ind + 2) % 4];
return(ordered_pts);
}
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);
}
public static double Norm(Point pt1, Point pt2)
{
double length = PA.Norm(PA.Subtract(pt1, pt2));
return(length);
}
