public class CustomDwgEntityController : DwgEntityController
{
    public override bool SupportPaint3d
        {
            get
            {
                return true;
            }
        }

    protected override void OnPaintEntity(DwgEntity entity, PaintEntityEventArgs args)
    {
        var e = (CustomDwgEntity)entity;
        var block = e.GetPlan(args.AnnotationScale);
        if (block != null)
        {
            Vector3D position, scale;
            double angle;
            e.Matrix.GetElementView(out position, out scale, out angle);
            PaintEntityEventArgs.PaintEntities(e, block, position, scale, angle, args);
        }
    }

    public override IEnumerable GetGrips(DwgEntity entity, object cadview)
    {
        var e = (CustomDwgEntity)entity;
        var has_grips = false;
        var grip = new EntityGrip(((CadView)cadview), entity);
        grip.Location = e.Position;
        var z = e.Position.Z;
        grip.Move += delegate (Vector3D vertex)
        {
            e.Position = new Vector3D(vertex.Pos, z);
        };
        yield return grip;
    }
    
    protected override void OnPaintEntity3d(DwgEntity entity, PaintEntityEventArgs args)
    {
        var e = (CustomDwgEntity)entity;
        var dc = args.Pen.DeviceContext;
        if (args.Pen.DeviceContext.gContains(e.Bounds3d))
        {
            var cache = e.GetCache();
            if (cache != null)
            {
                var pivot = dc.Pivot;
                dc.Pivot = e.Position;
                try
                {
                    cache.Paint(dc);
                }
                finally
                {
                    dc.Pivot = pivot;
                }
            }
        }
    }

    public override double? Fire(DwgEntity entity, Ray3D ray)
    {
        var e = (CustomDwgEntity)entity;
        return e.Fire(ray);
    }
}