I was just easing back into post-AU work – dealing with my email backlog and thinking about possible blog posts for the week – when I received a very welcome email from Philippe Leefsma, a member of the DevTech team based in Prague. Philippe had a bit of time to spare during our annual DevDays tour and decided to polish up a sample he’d been working on for posting. It extends a post of mine from four years ago (I can’t believe it’s been that long, but anyway), which shows how to jig a polyline with keywords. Philippe adjusted the code to modify the bulge factor of the current arc segment dynamically based on the cursor position – very much as the standard PLINE command does, in fact.
Here’s the C# code, with a few minor – mostly formatting – modifications from my side:
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.Runtime;
using System;
namespace PolylineJig
{
class JigUtils
{
// Custom ArcTangent method, as the Math.Atan
// doesn't handle specific cases
public static double Atan(double y, double x)
{
if (x > 0)
return Math.Atan(y / x);
else if (x < 0)
return Math.Atan(y / x) - Math.PI;
else // x == 0
{
if (y > 0)
return Math.PI;
else if (y < 0)
return -Math.PI;
else // if (y == 0) theta is undefined
return 0.0;
}
}
// Computes Angle between current direction
// (vector from last vertex to current vertex)
// and the last pline segment
public static double ComputeAngle(
Point3d startPoint, Point3d endPoint,
Vector3d xdir, Matrix3d ucs
)
{
Vector3d v =
new Vector3d(
(endPoint.X - startPoint.X) / 2,
(endPoint.Y - startPoint.Y) / 2,
(endPoint.Z - startPoint.Z) / 2
);
double cos = v.DotProduct(xdir);
double sin =
v.DotProduct(
Vector3d.ZAxis.TransformBy(ucs).CrossProduct(xdir)
);
return Atan(sin, cos);
}
}
public class BulgePolyJig : EntityJig
{
Point3d _tempPoint;
Plane _plane;
bool _isArcSeg = false;
bool _isUndoing = false;
Matrix3d _ucs;
public BulgePolyJig(Matrix3d ucs) : base(new Polyline())
{
_ucs = ucs;
Vector3d normal = Vector3d.ZAxis.TransformBy(ucs);
_plane = new Plane(Point3d.Origin, normal);
Polyline pline = Entity as Polyline;
pline.SetDatabaseDefaults();
pline.Normal = normal;
AddDummyVertex();
}
protected override SamplerStatus Sampler(JigPrompts prompts)
{
JigPromptPointOptions jigOpts = new JigPromptPointOptions();
jigOpts.UserInputControls =
(UserInputControls.Accept3dCoordinates |
UserInputControls.NullResponseAccepted |
UserInputControls.NoNegativeResponseAccepted);
_isUndoing = false;
Polyline pline = Entity as Polyline;
if (pline.NumberOfVertices == 1)
{
// For the first vertex, just ask for the point
jigOpts.Message = "\nSpecify start point: ";
}
else if (pline.NumberOfVertices > 1)
{
string msgAndKwds =
(_isArcSeg ?
"\nSpecify endpoint of arc or [Line/Undo]: " :
"\nSpecify next point or [Arc/Undo]: "
);
string kwds = (_isArcSeg ? "Line Undo" : "Arc Undo");
jigOpts.SetMessageAndKeywords(msgAndKwds, kwds);
}
else
return SamplerStatus.Cancel; // Should never happen
// Get the point itself
PromptPointResult res = prompts.AcquirePoint(jigOpts);
if (res.Status == PromptStatus.Keyword)
{
if (res.StringResult.ToUpper() == "ARC")
_isArcSeg = true;
else if (res.StringResult.ToUpper() == "LINE")
_isArcSeg = false;
else if (res.StringResult.ToUpper() == "UNDO")
_isUndoing = true;
return SamplerStatus.OK;
}
else if (res.Status == PromptStatus.OK)
{
// Check if it has changed or not (reduces flicker)
if (_tempPoint == res.Value)
return SamplerStatus.NoChange;
else
{
_tempPoint = res.Value;
return SamplerStatus.OK;
}
}
return SamplerStatus.Cancel;
}
protected override bool Update()
{
// Update the dummy vertex to be our 3D point
// projected onto our plane
Polyline pl = Entity as Polyline;
if (_isArcSeg)
{
Point3d lastVertex =
pl.GetPoint3dAt(pl.NumberOfVertices - 2);
Vector3d refDir;
if (pl.NumberOfVertices < 3)
refDir = new Vector3d(1.0, 1.0, 0.0);
else
{
// Check bulge to see if last segment was an arc or a line
if (pl.GetBulgeAt(pl.NumberOfVertices - 3) != 0)
{
CircularArc3d arcSegment =
pl.GetArcSegmentAt(pl.NumberOfVertices - 3);
Line3d tangent = arcSegment.GetTangent(lastVertex);
// Reference direction is the invert of the arc tangent
// at last vertex
refDir = tangent.Direction.MultiplyBy(-1.0);
}
else
{
Point3d pt =
pl.GetPoint3dAt(pl.NumberOfVertices - 3);
refDir =
new Vector3d(
lastVertex.X - pt.X,
lastVertex.Y - pt.Y,
lastVertex.Z - pt.Z
);
}
}
double angle =
JigUtils.ComputeAngle(
lastVertex, _tempPoint, refDir, _ucs
);
// Bulge is defined as tan of one fourth of included angle
// Need to double the angle since it represents the included
// angle of the arc
// So formula is: bulge = Tan(angle * 2 * 0.25)
double bulge = Math.Tan(angle * 0.5);
pl.SetBulgeAt(pl.NumberOfVertices - 2, bulge);
}
else
{
// Line mode. Need to remove last bulge if there was one
if (pl.NumberOfVertices > 1)
pl.SetBulgeAt(pl.NumberOfVertices - 2, 0);
}
pl.SetPointAt(
pl.NumberOfVertices - 1, _tempPoint.Convert2d(_plane)
);
return true;
}
public bool IsUndoing
{
get
{
return _isUndoing;
}
}
public void AddDummyVertex()
{
// Create a new dummy vertex... can have any initial value
Polyline pline = Entity as Polyline;
pline.AddVertexAt(
pline.NumberOfVertices, new Point2d(0, 0), 0, 0, 0
);
}
public void RemoveLastVertex()
{
Polyline pline = Entity as Polyline;
// Let's first remove our dummy vertex
if (pline.NumberOfVertices > 0)
pline.RemoveVertexAt(pline.NumberOfVertices - 1);
// And then check the type of the last segment
if (pline.NumberOfVertices >= 2)
{
double blg = pline.GetBulgeAt(pline.NumberOfVertices - 2);
_isArcSeg = (blg != 0);
}
}
public void Append()
{
Database db = HostApplicationServices.WorkingDatabase;
Transaction tr =
db.TransactionManager.StartTransaction();
using (tr)
{
BlockTable bt =
tr.GetObject(
db.BlockTableId, OpenMode.ForRead
) as BlockTable;
BlockTableRecord btr =
tr.GetObject(
bt[BlockTableRecord.ModelSpace], OpenMode.ForWrite
) as BlockTableRecord;
btr.AppendEntity(this.Entity);
tr.AddNewlyCreatedDBObject(this.Entity, true);
tr.Commit();
}
}
[CommandMethod("BPJIG")]
public static void RunBulgePolyJig()
{
Document doc = Application.DocumentManager.MdiActiveDocument;
Database db = doc.Database;
Editor ed = doc.Editor;
BulgePolyJig jig =
new BulgePolyJig(ed.CurrentUserCoordinateSystem);
while (true)
{
PromptResult res = ed.Drag(jig);
switch (res.Status)
{
// New point was added, keep going
case PromptStatus.OK:
jig.AddDummyVertex();
break;
// Keyword was entered
case PromptStatus.Keyword:
if (jig.IsUndoing)
jig.RemoveLastVertex();
break;
// If the jig completed successfully, add the polyline
case PromptStatus.None:
jig.RemoveLastVertex();
jig.Append();
return;
// User cancelled the command, get out of here
// and don't forget to dispose the jigged entity
default:
jig.Entity.Dispose();
return;
}
}
}
}
}
Here’s the BPJIG command in action, jigging a polyline with arc segments:
Now it must be noted that this implementation is some way from re-implementing the full PLINE command – for those of you who like to re-invent the wheel ;-) - but it should provide some idea of how to allow users to input bulge factors for polyline segments that are being jigged by your custom commands.
Thanks, Philippe! :-)
Update
It was pointed out in a comment (thanks, Igor :-) that the above code doesn't work for all UCS settings (especially when there's a custom origin defined). I've done my best to address this in the below code: if it doesn't work for your specific situation, please do let me know.
(I've included the code in its entirety, but the only changes were to the BulgePolyJig() constructor, in case you want to integrate with existing code.)
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.Runtime;
using System;
namespace PolylineJig
{
class JigUtils
{
// Custom ArcTangent method, as the Math.Atan
// doesn't handle specific cases
public static double Atan(double y, double x)
{
if (x > 0)
return Math.Atan(y / x);
else if (x < 0)
return Math.Atan(y / x) - Math.PI;
else // x == 0
{
if (y > 0)
return Math.PI;
else if (y < 0)
return -Math.PI;
else // if (y == 0) theta is undefined
return 0.0;
}
}
// Computes Angle between current direction
// (vector from last vertex to current vertex)
// and the last pline segment
public static double ComputeAngle(
Point3d startPoint, Point3d endPoint,
Vector3d xdir, Matrix3d ucs
)
{
Vector3d v =
new Vector3d(
(endPoint.X - startPoint.X) / 2,
(endPoint.Y - startPoint.Y) / 2,
(endPoint.Z - startPoint.Z) / 2
);
double cos = v.DotProduct(xdir);
double sin =
v.DotProduct(
Vector3d.ZAxis.TransformBy(ucs).CrossProduct(xdir)
);
return Atan(sin, cos);
}
}
public class BulgePolyJig : EntityJig
{
Point3d _tempPoint;
Plane _plane;
bool _isArcSeg = false;
bool _isUndoing = false;
Matrix3d _ucs;
public BulgePolyJig(Matrix3d ucs) : base(new Polyline())
{
_ucs = ucs;
// Get the coordinate system for the UCS passed in, and
// create a plane with the same normal (but we won't use
// the same origin)
CoordinateSystem3d cs = ucs.CoordinateSystem3d;
Vector3d normal = cs.Zaxis;
_plane = new Plane(Point3d.Origin, normal);
// Access our polyline and set its normal
Polyline pline = Entity as Polyline;
pline.SetDatabaseDefaults();
pline.Normal = normal;
// Check the distance from the plane to the coordinate
// system's origin (wwe could use Plane.DistanceTo(), but
// then we also need the vector to determine whether it is
// co-directional with the normal)
Point3d closest = cs.Origin.Project(_plane, normal);
Vector3d disp = closest - cs.Origin;
// Set the elevation based on the direction of the vector
pline.Elevation =
disp.IsCodirectionalTo(normal) ? -disp.Length : disp.Length;
AddDummyVertex();
}
protected override SamplerStatus Sampler(JigPrompts prompts)
{
JigPromptPointOptions jigOpts = new JigPromptPointOptions();
jigOpts.UserInputControls =
(UserInputControls.Accept3dCoordinates |
UserInputControls.NullResponseAccepted |
UserInputControls.NoNegativeResponseAccepted |
UserInputControls.GovernedByOrthoMode);
_isUndoing = false;
Polyline pline = Entity as Polyline;
if (pline.NumberOfVertices == 1)
{
// For the first vertex, just ask for the point
jigOpts.Message = "\nSpecify start point: ";
}
else if (pline.NumberOfVertices > 1)
{
string msgAndKwds =
(_isArcSeg ?
"\nSpecify endpoint of arc or [Line/Undo]: " :
"\nSpecify next point or [Arc/Undo]: "
);
string kwds = (_isArcSeg ? "Line Undo" : "Arc Undo");
jigOpts.SetMessageAndKeywords(msgAndKwds, kwds);
}
else
return SamplerStatus.Cancel; // Should never happen
// Get the point itself
PromptPointResult res = prompts.AcquirePoint(jigOpts);
if (res.Status == PromptStatus.Keyword)
{
if (res.StringResult.ToUpper() == "ARC")
_isArcSeg = true;
else if (res.StringResult.ToUpper() == "LINE")
_isArcSeg = false;
else if (res.StringResult.ToUpper() == "UNDO")
_isUndoing = true;
return SamplerStatus.OK;
}
else if (res.Status == PromptStatus.OK)
{
// Check if it has changed or not (reduces flicker)
if (_tempPoint == res.Value)
return SamplerStatus.NoChange;
else
{
_tempPoint = res.Value;
return SamplerStatus.OK;
}
}
return SamplerStatus.Cancel;
}
protected override bool Update()
{
// Update the dummy vertex to be our 3D point
// projected onto our plane
Polyline pl = Entity as Polyline;
if (_isArcSeg)
{
Point3d lastVertex =
pl.GetPoint3dAt(pl.NumberOfVertices - 2);
Vector3d refDir;
if (pl.NumberOfVertices < 3)
refDir = new Vector3d(1.0, 1.0, 0.0);
else
{
// Check bulge to see if last segment was an arc or a line
if (pl.GetBulgeAt(pl.NumberOfVertices - 3) != 0)
{
CircularArc3d arcSegment =
pl.GetArcSegmentAt(pl.NumberOfVertices - 3);
Line3d tangent = arcSegment.GetTangent(lastVertex);
// Reference direction is the invert of the arc tangent
// at last vertex
refDir = tangent.Direction.MultiplyBy(-1.0);
}
else
{
Point3d pt =
pl.GetPoint3dAt(pl.NumberOfVertices - 3);
refDir =
new Vector3d(
lastVertex.X - pt.X,
lastVertex.Y - pt.Y,
lastVertex.Z - pt.Z
);
}
}
double angle =
JigUtils.ComputeAngle(
lastVertex, _tempPoint, refDir, _ucs
);
// Bulge is defined as tan of one fourth of included angle
// Need to double the angle since it represents the included
// angle of the arc
// So formula is: bulge = Tan(angle * 2 * 0.25)
double bulge = Math.Tan(angle * 0.5);
pl.SetBulgeAt(pl.NumberOfVertices - 2, bulge);
}
else
{
// Line mode. Need to remove last bulge if there was one
if (pl.NumberOfVertices > 1)
pl.SetBulgeAt(pl.NumberOfVertices - 2, 0);
}
pl.SetPointAt(
pl.NumberOfVertices - 1, _tempPoint.Convert2d(_plane)
);
return true;
}
public bool IsUndoing
{
get
{
return _isUndoing;
}
}
public void AddDummyVertex()
{
// Create a new dummy vertex... can have any initial value
Polyline pline = Entity as Polyline;
pline.AddVertexAt(
pline.NumberOfVertices, new Point2d(0, 0), 0, 0, 0
);
}
public void RemoveLastVertex()
{
Polyline pline = Entity as Polyline;
// Let's first remove our dummy vertex
if (pline.NumberOfVertices > 0)
pline.RemoveVertexAt(pline.NumberOfVertices - 1);
// And then check the type of the last segment
if (pline.NumberOfVertices >= 2)
{
double blg = pline.GetBulgeAt(pline.NumberOfVertices - 2);
_isArcSeg = (blg != 0);
}
}
public void Append()
{
Database db = HostApplicationServices.WorkingDatabase;
Transaction tr =
db.TransactionManager.StartTransaction();
using (tr)
{
BlockTable bt =
tr.GetObject(
db.BlockTableId, OpenMode.ForRead
) as BlockTable;
BlockTableRecord btr =
tr.GetObject(
bt[BlockTableRecord.ModelSpace], OpenMode.ForWrite
) as BlockTableRecord;
btr.AppendEntity(this.Entity);
tr.AddNewlyCreatedDBObject(this.Entity, true);
tr.Commit();
}
}
[CommandMethod("BPJIG")]
public static void RunBulgePolyJig()
{
Document doc = Application.DocumentManager.MdiActiveDocument;
Database db = doc.Database;
Editor ed = doc.Editor;
BulgePolyJig jig =
new BulgePolyJig(ed.CurrentUserCoordinateSystem);
while (true)
{
PromptResult res = ed.Drag(jig);
switch (res.Status)
{
// New point was added, keep going
case PromptStatus.OK:
jig.AddDummyVertex();
break;
// Keyword was entered
case PromptStatus.Keyword:
if (jig.IsUndoing)
jig.RemoveLastVertex();
break;
// If the jig completed successfully, add the polyline
case PromptStatus.None:
jig.RemoveLastVertex();
jig.Append();
return;
// User cancelled the command, get out of here
// and don't forget to dispose the jigged entity
default:
jig.Entity.Dispose();
return;
}
}
}
}
}
