Hi!
I'm trying to draw an arc in Autocad, with class Arc, and the constructor
Arc(Point3d center, Vector3d normal, double radius, double startAngle, double endAngle).
My problem is that I don't find almost anything in the documentation, and when I draw an arc, it has a phase difference between the place in what it should be and the place it is. I think it depends on the quadrant, but I'm not sure.
The angles that I use are measured in the reference system XY. Maybe the reference system changes depending on the plane of the arc (?)
My class is really simple:
public class Arco2d
{
# region ATRIBUTOS
Point2d startPoint;
Point2d middlePoint;
Point2d endPoint;
Point2d centro;
Point3d centro3d;
double radio;
double startAngle;
double endAngle;
#endregion
#region GETTERS
public Point2d StartPoint { get { return startPoint; } }
public Point2d MiddlePoint { get { return middlePoint; } }
public Point2d EndPoint { get { return endPoint; } }
public Point2d Centro { get { return centro; } }
public Point3d Centro3d { get { return centro3d; } }
public double Radio { get { return radio; } }
public double StartAngle { get { return startAngle; } }
public double EndAngle { get { return endAngle; } }
#endregion
/// <summary>
/// Construye un arco a partir de tres puntos.
/// </summary>
/// <param name="startPoint"></param>
/// <param name="middlePoint"></param>
/// <param name="endPoint"></param>
public Arco2d(Point2d startPoint, Point2d middlePoint, Point2d endPoint)
{
this.startPoint = startPoint;
this.middlePoint = middlePoint;
this.endPoint = endPoint; calcRadioYCentro(startPoint, middlePoint, endPoint); calcAngulos();
}
# region Métodos Privados
/// <summary>
/// Calcula el radio y centro del círculo que contiene al arco definido por los tres puntos.
/// </summary>
/// <param name="p1"></param>
/// <param name="p2"></param>
/// <param name="p3"></param>
private void calcRadioYCentro(Point2d p1, Point2d p2, Point2d p3)
{
double k1 = p1.X * p2.Y + p3.X * p1.Y + p2.X * p3.Y - p1.X * p3.Y - p2.X * p1.Y - p3.X * p2.Y;
double k2 = -(p1.X * p1.X + p1.Y * p1.Y);
double k3 = p2.Y - p3.Y;
double k4 = p3.X - p2.X;
double k5 = p2.X * p2.X + p2.Y * p2.Y;
double k6 = p1.Y - p3.Y;
double k7 = p3.X - p1.X;
double k8 = -(p3.X * p3.X + p3.Y * p3.Y);
double k9 = p1.Y - p2.Y;
double k10 = p2.X - p1.X;
double a1 = p2.X * p3.Y - p3.X * p2.Y;
double a2 = p1.X * p3.Y - p3.X * p1.Y;
double a3 = p1.X * p2.Y - p2.X * p1.Y;
double a = (k2 * k3 + k5 * k6 + k8 * k9) / k1;
double b = (k2 * k4 + k5 * k7 + k8 * k10) / k1;
double c = -(k2 * a1 + k5 * a2 + k8 * a3) / k1;
double centrox = a / 2;
double centroy = b / 2;
this.radio = Math.Sqrt(c + (a / 2) * (a / 2) + (b / 2) * (b / 2));
this.centro = new Point2d(-centrox, -centroy);
}
/// <summary>
/// Calcula los ángulos de comienzo y fin del arco.
/// </summary>
private void calcAngulos()
{
double d1, d2, d3, d4; d1 = startPoint.Y - centro.Y; d2 = endPoint.Y - centro.Y; d3 = startPoint.X - centro.X; d4 = endPoint.X - centro.X; startAngle = Math.Atan(d1 / d3); endAngle = Math.Atan(d2 / d4);
if (d3 < 0) // cuadrante 2 y 3
{ startAngle += Math.PI;
}
else if (d3 > 0 && d1 < 0) // cuadrante 4
{ startAngle += 2 * Math.PI;
}
if (d4 < 0) // cuadrante 2 y 3
{ endAngle += Math.PI;
}
else if (d4 > 0 && d2 < 0) // cuadrante 4
{ endAngle += 2 * Math.PI;
}
}
#endregion
#region Métodos Públicos
/// <summary>
/// Dibuja un objeto Arc a partir de los parámetros de esta clase.
/// </summary>
public void addArc2layer()
{
// Get the current document and database
Document acDoc = Application.DocumentManager.MdiActiveDocument;
Database acCurDb = acDoc.Database;
// Start a transaction using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
{
// Open the Block table for read
BlockTable acBlkTbl; acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId,
OpenMode.ForRead) as BlockTable;
// Open the Block table record Model space for write
BlockTableRecord acBlkTblRec; acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace],
OpenMode.ForWrite) as BlockTableRecord;
Arc acArc = new Arc(new Point3d(centro.X, centro.Y, 0), radio, startAngle, endAngle); acArc.SetDatabaseDefaults();
// Add the new object to the block table record and the transaction acBlkTblRec.AppendEntity(acArc); acTrans.AddNewlyCreatedDBObject(acArc, true);
// Save the new line to the database acTrans.Commit();
}
}
/// <summary>
/// Aún sin terminar. Revisar.
/// </summary>
/// <param name="centro"></param>
/// <param name="normal"></param>
public void addArc2layer(Point3d centro, Vector3d normal)
{
// Get the current document and database
Document acDoc = Application.DocumentManager.MdiActiveDocument;
Database acCurDb = acDoc.Database;
// Start a transaction using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
{
// Open the Block table for read
BlockTable acBlkTbl; acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId,
OpenMode.ForRead) as BlockTable;
// Open the Block table record Model space for write
BlockTableRecord acBlkTblRec; acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace],
OpenMode.ForWrite) as BlockTableRecord;
Arc acArc = new Arc(centro, normal, radio, startAngle, endAngle); acArc.SetDatabaseDefaults();
// Add the new object to the block table record and the transaction acBlkTblRec.AppendEntity(acArc); acTrans.AddNewlyCreatedDBObject(acArc, true);
// Save the new line to the database acTrans.Commit();
}
}
#endregion
}
Any help would be great!
