sort points by different UCS

[stefanveurink68AXD]

Guys, 

Not sure if this can be done: 

Found this code once to sort a point3dcollection on their x-coordinate: 

            Point3dCollection punten2 = new Point3dCollection(
            punten
            .Cast<Point3d>()
            .OrderBy(point => point.X)
            .ToArray());

What is needed now is to sort the points on their position in a different UCS. 
However, their original value's need to stay the same. 

Purpose is placing a RotatedDimension.

Is this possible to do? Can u give me any direction?

[norman.yuan]

Something like:

Point3dCollection punten2 = new Point3dCollection(
            punten
            .Cast<Point3d>()
            .OrderBy(point => point.X.TranformedBy(ed.CurrentUserCoordinateSystem))
            .ToArray());

I believe calling TransformedBy() in the .OrderBy clause would not change the points in the collection themselves, it only calculates the transform value for sorting, because Point3d is value type, not reference type. That is, Point3d.TransformBy() returns a new Point3d, the original Point3d is not changed, only a copy of it is passed into TransformBy() method. On the other hand. Entity.TransformedBy() is void method, that is, TransformedBy() is applied to the Entity itself.

[_gile · Accepted solution]

I think it should have been:

Matrix3d xform = ed.CurrentUserCoordinateSystem.Inverse();
Point3dCollection punten2 = new Point3dCollection(
    punten
    .Cast<Point3d>()
    .OrderBy(point => point.TranformBy(xform).X)
    .ToArray());