CircularArc2d.md

CircularArc2d Struct

Overview

The CircularArc2d struct represents a circular arc in 2D space (XY plane), defined by center, radius, and start/end angles.

Namespace

Autodesk.AutoCAD.Geometry

Key Properties

Property	Type	Description
Center	Point2d	Gets the center point of the arc
Radius	double	Gets the radius of the arc
StartAngle	double	Gets the start angle (radians)
EndAngle	double	Gets the end angle (radians)
StartPoint	Point2d	Gets the start point of the arc
EndPoint	Point2d	Gets the end point of the arc

Constructors

Constructor	Description
CircularArc2d(Point2d, double)	Creates full circle
CircularArc2d(Point2d, double, double, double)	Creates arc with start/end angles

Key Methods

Method	Return Type	Description
GetClosestPointTo(Point2d)	Point2d	Gets closest point on arc to given point
DistanceTo(Point2d)	double	Gets distance from point to arc
IsOn(Point2d)	bool	Checks if point is on arc

Code Examples

Example 1: Creating 2D Arcs

Point2d center = new Point2d(0, 0);
double radius = 10.0;
double startAngle = 0;
double endAngle = Math.PI / 2; // 90 degrees

CircularArc2d arc = new CircularArc2d(center, radius, startAngle, endAngle);

ed.WriteMessage($"\nArc radius: {arc.Radius}");
ed.WriteMessage($"\nStart point: ({arc.StartPoint.X:F2}, {arc.StartPoint.Y:F2})");
ed.WriteMessage($"\nEnd point: ({arc.EndPoint.X:F2}, {arc.EndPoint.Y:F2})");

Related Classes

• CircularArc3d - 3D circular arc
• Point2d - 2D center and points
• Arc - AutoCAD arc entity

References

• Autodesk Official Documentation