.MDL files versus .BGL files for scenery

Discussion related to terrain/scenery design.
Posts: 4
Joined: Thu Mar 24, 2011 7:28 pm

Postby jefox » Fri Jun 17, 2011 1:58 pm

I have a question regarding scenery files formats. I think I understand the difference between the two formats in the subject line, but for clarification:

A .BGL file is a library of objects (1 or many) that, when the simulator is run, are just THERE. Using a tool like LibraryCreatorXML (http://www.fsdeveloper.com/wiki/index.php?title=Library_Creator_XML_2.0). I create a .BGL file with the model(s), a placement.BGL file as well, drop the two in the Addon Scenery/Scenery folder, and there they are in the world.

A .MDL file is just a single scenery object, and I can place that, along with the placement.BGL file into the Addon Scenery folder. From there it is then accessible from, say, the Object Placement tool. Then I can place it somewhere for a specific flight/mission, etc.

Is that correct?

Posts: 134
Joined: Sun Mar 06, 2011 11:24 am

Postby scruffyduck » Tue Jun 21, 2011 3:48 am

Mdl files are models as described above. In the scenery sense you cannot have an mdl file directly accessed by the Sim. It must be in a Bgl file. We can put a bunch of models into a single Bgl file. This is usually called a library. Other bgl files containing placement code can then reference the models by their GUID. This means the model is stored once and referenced (placed) multiple times.

If an model is compiled into a bgl file along with placement code for it then it is really no different from the library (in the way the model is compiled into the Bgl format). However if there is placement code with it then restrictions appear as to where that model can be placed elsewhere. So putting a single model into a Bgl file along with placement code does not stop the model being called from another Bgl file. You can obviously place that model as many times as you like by having multiple placement code in the same Bgl file as the model. At the same time you would find that, depending on a range of circumstances, the model could be placed using placement code in another Bgl file. The restrictions are often called 'geo locking' although this is a bit misleading and the 'rules' may allow the model to be placed within a limited distance from the location of the object as placed in the same file as the model right up to regional or other factors. We do not understand exactly how this works - although we assume the developers do!

Posts: 134
Joined: Sun Mar 06, 2011 11:24 am

Postby scruffyduck » Thu Jun 23, 2011 3:31 am

Yes it can and some folks have tested it I believe. At the moment it needs the user to manually set the folder locations. You will excuse me if I point out that using ADE for P3D where the resulting scenery is used in a commercial simulator (or for payware) consititutes commercial use and you would need a different license rather than the freeware one.

You are, of course, most welcome to try it out with P3D and I will be making P3D one of the options.

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