Topic: Point3d X value

[shers]

Hi,

It is not possible to assign value to Point3d Coordinates one by one, like Point3d insPt.X = 2. Is there any other option?

Thanks

[Jeff_M]

Point3d newpt = new Point3d(2, insPt.Y, insPt.Z);

[BlackBox]

Duplicate thread here:

http://forums.augi.com/showthread.php?161727-Point3d

[gile]

Hi,

The type Point3d, as many others .NET structures, is immutable.
You cannot edit a Point3d, you have to create a new one.

[gile]

If you really need a mutable point to improve performances* while you make many changes to a point coordinates, you can build a little class where the point coordinates are read/write enabled.
The mutable point type may have explicit cast operators from and to the Point3d type.

Code - C#: [Select]

1. using Autodesk.AutoCAD.Geometry;
2.  
3. namespace MutablePoint
4. {
5.     public class Point
6.     {
7.         public Point(double x, double y, double z)
8.         {
9.             this.X = x;
10.             this.Y = y;
11.             this.Z = z;
12.         }
13.  
14.         public double X { get; set; }
15.         public double Y { get; set; }
16.         public double Z { get; set; }
17.  
18.         public void Add(Vector3d disp)
19.         {
20.             this.X += disp.X;
21.             this.Y += disp.Y;
22.             this.Z += disp.Z;
23.         }
24.  
25.         public static explicit operator Point(Point3d pt)
26.         {
27.             return new Point(pt.X, pt.Y, pt.Z);
28.         }
29.  
30.         public static explicit operator Point3d(Point pt)
31.         {
32.             return new Point3d(pt.X, pt.Y, pt.Z);
33.         }
34.     }
35. }

Using:

Code - C#: [Select]

1. Point pt = (Point)Point3d.Origin;
2. pt.X = 10.0;
3. pt.Y = 20.0;
4. Point3d p3d = (Point3d)pt; // p3d = (10,20,0)

*mutable objects are more efficient with memory but immutable ones are safer ans easier to use in concurent programming.

[shers]

That's great! Thanks very much!

I also would like to know how to assign null value to Point3d, like
Point3d pt = null;

Thanks

[gile]

Hi,

It looks like you're missing very basics .NET.
As I said upper Point3d is a structure, not a class. Structures are value types and classes are reference type and a structure instance must have a value and cannot be null (see here).
So, you can use a Nullable type (Nullable<Point3d> or Point3d?) or use the Point class (as defined upper) instead of Point3d structure.

Anyway, I'm very curious about what kind of stuff you're doing which requires mutable and nullable points...

[ChrisCarlson]

:confused: how can a coordinate system contain a null value either in the X,Y,Z or the entire value?