II - Understanding FS2004 Aircraft
How does it work?
We assume you know that FS2004 has a folder named Aircraft where all planes are located and that every aircraft is a separate folder inside this one. You also know that every aircraft has basically four different folders. Let's take a look at the default 737-400:
- Flight Simulator 9
What interests us the more here is the textures folder, where the bmp files are. Those are the ones we will modify. You may have more than each one of those four different folders. Let's say we would like to creat a new livery for an Altair B737-400 repaint. We would create a new texture folder with a suffix like this (at the end):
- Flight Simulator 9
We could have called it texture.altair, texture.mine, texture.whatever. The same is true about the other folders. If you have another panel, you may create a new folder named, say panel.vintage and then put all the files in this new panel folder. The file named aircraft.cfg that is in the plane's root directory (b737_400 in our example) contains the instructions to which folder referrs to wich aircraft. At the top of the aircraft.cfg file (that you can open with any text editor like Notepad) you will find a section like the one below that contain the instructions for every plane. In the case of our ficticious Altair 737-400 with a vintage panel we would have something like this for that section:
If you are not very familiar with all this it would be a good idea for you to download and read the Microsoft Aircraft Container SDK. Microsoft names this folder structure for every plane as "Aircraft Container". Here is the link:
Now let's see a some more details about the texture and model folders.
The Model and Textures
The model folder has two files: one named model.cfg and the other named something.mdl. Of course the "something" from this last one is an arbitrary name chosen by the developer of the particular aircraft model. This mdl file is like a wireframe. It is the 3D "skeleton" of the plane and it is this file that 'tells' FS2004 where all textures have to go to cover the aircaft. In other words, it will take the different bmp texture files that are inside the texture folder and will put all those bmps together like a big puzzle. That is why you cannot mix different texture and model files from different planes. The mdl file will look inside the texture folder for specific file names to form the puzzle. If you put one mdl into another aircraft model folder it will try to look for file names that are not there and the plane will not load in FS. The model.cfg is a simple text file that you can open with Notepad and only contains the name of the mdl file.
Looking into the textures folder we will now see a lot of files here. Simpler planes have only a few, detailed planes can have a whole bunch of different files in there. There are a few conventions here.
Every aircraft modeler chooses how many and how big those files are. They can be 512 x 512 pixels wide or 1024 x 1024 pixels wide and range from only 256 kB to quite a few megabytes. You cannot open those files with your image editor yet as they are in an EXTENDED FORMAT. We have to first convert those to a format our softwares can open (24 kB format). When you open one of those files they look like a puzzle. There are aircraft parts displayed all over. Some are parts of the tail, some are parts of the fuselage, it is up to the modeler to see what goes where. In general they try to maximize space and put everything possible in a file to reduce the number of bmp files in the texture folder. The MSFS default planes are good examples. The less bmp files, the smaller the aircraft's total size in bytes it will be.
You will notice that there are the something_L.bmp files and the something_T.bmp files. The only difference between those is the letter _L and _T. The ones we are more interested are the ones ending with the _T. We will use both but the more important ones are those as they are the DAYLIGHT textures. That means, those are the surfaces of the aircraft you see during the day, and therefore the ones that actually have the livery of the airline painted on them. The other _L files are the NIGHT textures. Those are basically black textures with some white areas simulating what areas of the aircraft are visible at night. They are 'see-through' like images that tell FS2004 what to show from the _T textures at night.
The other two letters you may find are: _C for cockpit or inside textures and _D for damage or crash textures (thanks to our friend ALT393 Zafar for that).
When painting an aircraft we never have to edit all of the files that are in the texture folder. In fact many files contain the textures for the landing gears and structural parts that remain the same in all liveries. The most important parts we have to locate and paint are the textures containing the fuselage and the tail.
The Paint Kits
You must have heard about paint kits if you have ever been interested in painting a plane. Paint kits vary greatly. You have some very, very good paint kits that have all parts of a texture file separated for you in different layers, ready to be used with most popular image editors. Some even have shades, dust and dirt layers ready. The most popular format is .psd for Adobe Photoshop. But even if you do not have Photoshop you may import and convert those files to the format of the editor you use. Some other paint kits are just plain blank (white) textures. You still have to separate all the elements like windows, seams, etc (do not worry about that now, we will get there) to form the different layers but at least you do not have to remove the paint from another livery before painting the one you want to. Those are time savers as well even when they do not have all the work done for you.
Simply put those are the reflections introduced with later versions of FS, typically those from metallic surfaces. In practice, Alpha Channels are separate bitmaps that are later combined to a fuselage image for example to form a single texture bitmap. You have two kinds of bmp files. You may have 24 kB files and 32 kB files. The 24kB files are those bmps you normally open in your image editor. When they combine this other alpha channel (the alpha channels are 8 kB files) they form the 32 kB bmps. When you later convert those bmps to use with Flight Simulator you then have the EXTENDED bmp format that contains all the information for FS2004 to create the reflections. Of course we will detail this a lot when we get there later. This is just for you to know what they are. For now it is enough for you to know that alpha channels are greyscale images, that is, only black, white and grey. If you want a texture to have a lot of reflection, you paint the area darker, if you want it to have no reflection at all, you paint it white. When you superimpose those two images FS2004 will know wich parts of the EXTENDED bmp will not have reflections, wich ones do and how much they will have. But as I said, do not worry about it now.
Now you know how it works and what do we have to paint. Let's start our first work now, shall we?