Find a rectangle(box) from block

[dlwotj4274]

Hello

I would like to get a rectangle(box) which is enclosed by lines and polylines in a block.


It is a block. it was drown by lines and polylines for rectangle.
I want to get a each of boxes of handle, location something like that.

Thank you for your support always

Jaeseo

[support]

Hello Jaeseo,

If the sought rectangular area is enclosed by a single entity (e.g. LWPolyline or Polyline), it can be obtained through a CADPolyLine.Box property. In case the rectangular area is enclosed by several lines and polylines, you will have to read start and end points of each CADLine and vertices of each CADPolyLine in a block and then find the top-left (Xmin, Ymax) and the bottom-right (Xmax, Ymin) point from the read points.

To get a two-dimensional bounding box (DRect) from the top-left (Xmin, Ymax) and the bottom-right (Xmax, Ymin) points, use the following DRect constructor:

Code: Select all

double Xmin, Ymax, Xmax, Ymin;
...

DRect box = new DRect(Xmin, Ymax, Xmax, Ymin);

Mikhail

[dlwotj4274]

Thank you for your comment

I'm trying to get a rectangle from block.

Could I find a intesection(crossing) of two lines or polylines by using DPoint. Cross Method?

[support]

Jaeseo,

You are welcome.

DPoint.Cross method calculates the cross product between two vectors. To understand the cross product, please refer to the following article: https://betterexplained.com/articles/cross-product/.

If you need to find the intersection of two lines that are in the X-Y plane, please try the method below.

Code: Select all

public static CAD2DPoint FindIntersectionOfLines(DPoint s1, DPoint e1, DPoint s2, DPoint e2)
{
    double a1 = e1.Y - s1.Y;
    double b1 = s1.X - e1.X;
    double c1 = a1 * s1.X + b1 * s1.Y;

    double a2 = e2.Y - s2.Y;
    double b2 = s2.X - e2.X;
    double c2 = a2 * s2.X + b2 * s2.Y;

    double delta = a1 * b2 - a2 * b1;
    //If lines are parallel, the result will be (NaN, NaN).
    return delta == 0 ? new CAD2DPoint(double.NaN, double.NaN)
        : new CAD2DPoint((b2 * c1 - b1 * c2) / delta, (a1 * c2 - a2 * c1) / delta);
}

The arguments s1 and e1 take the start and the end point of the first CADLine, respectively.
The arguments s2 and e2 take the start and the end point of the second CADLine, respectively.

In the case of 2 polylines you will need to check each line segment of one polyline against each line segment of the other polyline for intersection.

Mikhail