FSX: Questions About The Export Process

I have received some interesting questions about our export process and some of the changes in there. Thought it would be a good idea to answer these questions as a blog posts as some of the answers could be relevant (and informative) to several other FS fans out there...

"Firstly will the export process still take place through MakeMDl.exe. Personally I use Flight Simulator Design Studio 3 by Abacus as my preferred modelling tool and am therefore anxious to clarify that models produced with that program will still be usable."

As a whole, we are moving away from .BGL models toward a new format which is more static. (of course BGL files are still supported for backward compatibility). Although BGL files allow a huge amount of flexibility, their dynamic nature does not pair well with today's rendering hardware. Since we cannot assume what the geometry of a model would be from frame to frame within a BGL file, we essentially have to parse the stream every frame and reconstruct the geometry every frame. When dealing with models of a few hundred polygons, the cost isn't too bad but when we start putting models with 20,000+ polygons. The performance impact is SIGNIFICANT! Because of this we have been moving our model pipeline to use a more static geometry format and moved some of the flexibility towards other scripted approaches (such as the part visibility scheme I discussed earlier).

Now, coming back to MakeMDL.exe, it is being deprecated towards a new tool called XtoMDL.exe which essentially takes a .X file and converts it to the new MDL format. This will require some work from 3rd parties to support this new format but the XtoMDL tool also has an intermediate XML form which allows us to support other native file formats.

Models produced with older tools will still work, we always have a strong commitment to our 3rd party developers and backward compatibility is key to Flight Sim. That being said, for optimal performance in-game, moving old model formats to the new format is strongly recommended...

"Secondly will the ModelDef.Xml file be used in the same way as MakeMdl.Parts.Xml ? ie the model drawing it's animations from the file during compile prior to export as .mdl"

The core concept of ModelDef.Xml is the same. The animation information is pulled from this file during the export process and is "baked" into the final model file. The main difference is that we wanted the animation information to be independent from the name of the model parts within the authoring tool. We also wanted to add new features such as part visibility within the model format and do a general clean-up of the file format.

"I have send a lot of time writing xml code, mainly centred around the VC ( the model has no 2D cockpit ) and therefore hope that the vast majority of code can be transposed from MakeMdl.Parts to ModelDef with minor alterations to the syntax."

For the most part, the same XML data will still work with some format tweaking. The core data essentially follows the same XML form but most components are also wrapped in higher level elements to group other details relevant to animations such as part visibility, mouserect info, ... So the work involved will mostly be simple reformatting of your files.

"lastly I understand that Aces Studio now have a technical Author working on the SDK, can we hope for a simultaneous release of the SDK and the software ?"

Our plan has been from the start with this release to have the SDK ready when the product ships. This also means that beta releases of the SDK will likely be released around the same time as beta version of Flight Sim are available.


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