Record as TagObject

[DaveW]

I would like to store some extra text and numerical data in some GLScene HeightFields, for example datetime stamp, modified by name, a 2D array of Z values, etc. It seems to me that this should be possible using (something equivalent to) a record attached to the .TagObject however I can't work out how I should define the 'record' as an object and then how I can access the data.

1. Is this a sensible approach? Is there a better way?
2. How should I define the record/object, create the object & assign it to the HeightField, access the data.

David W

[Jerome.D (BeanzMaster)]

Hi Dave the better is instead of record is using a class and assign it to the tagobject. But becareful

Type
  TMyRecordClass = Class(TGLUpdatableObject) // or simply TObject
  private
    FData1 : Byte
    FData2 : Word
    etc....
   public
     Constructor Create; override;
     Desctructor Destroy;
     property Data1 : Byte Read FData1 write FData1
        etc....
    end;

In your code, for adding extra infos

       MyObjectData := TMyRecordClass.Create;
       MyObjectData.Data1 := 123;
        MyHeightFielad.TagObject := MyObjectData

Take care before close your form, you'll need traverse thë GLScene and free your "TMyRecordClass" objects yourself. Because actually Object and scene haven't got event "OnfreeObject" (it will be a good feature)

So in Form' CloseQuery event or similar you'll must do call a (recursive) freeing function like this, from scratch :

procedure TForm1.FreeTagObject(anObject : TGLBaseSceneObject);
Var
  i : Integer;
  TmpObject : TGLBaseSceneObject;
begin
  if anObject.count>0 then
  begin
    For i:=0 to anObject.Count-1 do
    begin
      TmpObject := GLScene1.Objects[i];
      if anObject.HasSubChildren then FreeTagObject(TmpObject);
      if assigned(TmpObject.TagObject) then
      begin
        TMyRecordClass(TmpObject.TagObject).Free;
        TmpObject.TagObject := nil;
      end;
    end;
  end;
end; 

procedure TForm1.FormCloseQuery(Sender : TObject; var CanClose : boolean);
begin
  FreeTagObject(GLScene1.Objects);
end;

In hope this could help you

Cheers

[DaveW]

Hi Jerome,
Thank you for the help! I will give it a try...
David.