2021-07-19c CAD secondary development creates multiple line segments

The code is as follows ：

        /// <summary>
        ///  Draw polyline segments 
        /// </summary>
        /// <param name="db"> Graphic database </param>
        /// <param name="isClosed"> Is it closed? </param>
        /// <param name="contantWidth"> Line width </param>
        /// <param name="vertices"> Fixed point of multi segment , Variable parameters </param>
        /// <returns>ObjectId</returns>
        public static ObjectId AddPolyLineToModelSpace(Database db, bool isClosed, double contantWidth, params Point2d[] vertices) 
        {
    
            if (vertices.Length < 2)
            {
    
                return ObjectId.Null;
            }
            // Declare a polyline object 
            Polyline pLine = new Polyline();
            // Add vertices of multiple segments 
            for (int i = 0; i < vertices.Length; i++)
            {
    
                pLine.AddVertexAt(i, vertices[i], 0, 0, 0);
            }
            if (isClosed)
            {
    
                pLine.Closed = true;
            }
            // Set the lineweight of multiple line segments 
            pLine.ConstantWidth = contantWidth;
            return AddEnityTool.AddEnityToModelSpace(db, pLine);
        }

polyline Attributes that can be added

 public void AddVertexAt(int index, Point2d pt, double bulge, double startWidth, double endWidth);

index： Add the sequence number of the point
pt： Added points
bulge： Convexity
startWidth： Start width
endWidth： End width
Definition of convexity ：
Let the center angle of the arc be A( Radians indicate ), Then convexity = Tangent value of quarter circle center angle
C# Express ：
Convexity =sin(A/4)/cos(A/4)