RA2/YR Structures: What are they?
by MooMan65. Published: 2/15/03. Last update: 3/10/03.

This tutorial describes the basic use of structures in the game, what the formatting of the files are that they use, and most importantly, how to add them into your own game so you can use them. The INI code which supports these new structures is not included here, and is beyond the scope of this article.

Structures are anything in the game that can be built from the Buildings or Armory tabs from the sidebar (as well as the many unbuildable structures in-game like civilian buildings). They are always stationary images which make up your base and most maps with an urban setting. Each structure usually has a specific purpose in the game whether it be to construct units, provide power, protect your base or simply to establish the appropriate atmosphere in a map. The classifications 'structure' also covered overlay-based structures like Walls and Pavement, they behave differently in-game, but still have the basic ground rules for every other structure.

The standard file format used by structures is the almighty .SHP file. These are kind of like archived of one or multiple .PCX images (not compressed) contined within the one file. This is very useful as, being a 2D game, Red Alert 2/Yuri's Revenge use a lot of standard images. Structures can also use .VXL (or Voxel) and .HVA files also, they are used for structures with turrets like the Sentry Gun. Voxel files were introduced in Tiberian Sun to somewhat add a crude 3D element into a standard 2D game.

Structures usually use a standard naming configuration for its .SHP files to make it both easy on modder and player. If you have downloaded any structures now and looked at their files you should see what looks like at first glace a bunch of random letters making up the name. Well actually there is a reason why it's laid out like that. Here's some examples below:

GACNST.SHP
NAMISL_A.SHP
YAPOWRMK.SHP

Let's color-code it so it's split up into the categories that mean something, the first three color codes are required by all filenames, but some files also contain certain things after the third colour:

GACNST??.SHP

• G - This first letter tells you which side the structure is available to. You have a choice between:
  G- Allies
  N - Soviets
  Y - Yuri
  C - Civilian
  Note: G and N are named the way they are from GDI and Nod from Tiberian Sun when they first introduced this naming convention, Westwood Pacific (later became EA Pacific), did not bother to remove those two and kept them for when they modified the Tiberian Sun engine into Red Alert 2.
   
• A - The second letter tells you what theater the .SHP file should be displayed in. By theater I mean the climate of the map you are playing, whether it be Temperate, Snow, Desert etc. The possible letters are below:
  G - Default*
  T - Temperate
  A - Snow (Artic)
  U - Urban
  The following are for Yuri's Revenge only:
  D - Desert
  N - NewUrban
  L - Lunar
   
  *Default is used whenever a specific theater file is not found for the map. So for example if a structure includes GG and GA groups of images, it will use the GA ones specifically on Snow maps, and GG everywhere else since there are no specific images for them. Usually those two are the only types of theater names you need, as there normally is no difference in building appearance for the rest of the theaters (saves space as well on your Hard Drive). However some structures, especially civilian and tech buildings, leave rubble behind which that image is specific to the theater, and so you need all theater names covered.

• CNST - The last critical part of the filename is usually a four letter code that tells you what structure it is. This code is also used for the ARTMD.INI entry to tell the game that this entry are for these group of images. CNST in this case stands for Construction Yard. So from the current information we know that this file contains the Snow images for the Allied Construction Yard!

• ?? - On some files as part of the structure package there are certain suffix's after the main code. While we know those three terms above will give you the structure information for every theater in the game, there still are other files involved in structures such as animations, bibs and buildups. This suffix tells you and the game what the file is used for, and then should be called in the ARTMD.INI file for that structure for it to be used in-game. The list of possible suffix's are below:
  _? - Animations (the ? can be a latter usually from A to E but there are special cases which you can look for yourself.)
  MK - Buildup (this is reserved for the buildup animation of the structure when it is placed down on the map.)
  BB - Bib (some structures use bibs so parts of the structure are considered flat and can be moved across by units. This includes the Service Depot's Pad and Airforce Command HQ's pads.)
  Of course these are simply the naming criteria used in the majority by Westwood/EA. You can actually do whatever suffix's you want, as long as you call them properly through the ARTMD.INI file. I tell you this as it's much easier for everyone to continue the trend. All my structure downloads here on MODDEN use this system, and most other people do to.

I said before that .SHP files are a collection of one or multiple .PCX files, so why multiple? Well, each .SHP file contains all the images needed for a specific purpose, such as an animation. Think of .SHP's as animated .GIF files, although the game is sophisticated enough to know when the .SHP file should be looping on simply to display one of the images contained in the .SHP on the screen. Overall there are three kinds of .SHP files relating to structures.

• Animations: Animation .SHP's are like animated .GIF's, they contain multiple images that, when looping, it looks like part of the structure is doing its 'stuff'. The ARTMD.INI file tells the game what image range to use inside the animation file for a specific animation of the structure. Meaning multiple animations can be read from the same .SHP file. This is most commonly done when the structure is at half health (the building becomes damaged). Usually an animation .SHP contains the images needed for the non-damages state of the structure, followed by the half-damaged, and finally the shadow frames for both sets of animations. The ARTMD.INI then tells the game which range of frames to use. eg. Animation A has 100 images inside it, 50 of those imags are shadows and 50 are the animation itself. 25 out of the first 50 are for the non-damaged animation, the next 25 for the damaged animation, the following 25 are the shadows for the non-damaged animation, and the last 25 are shadows for the damaged animation. Shadows are called for automatically from the game, so the first 25 frames will automatically use the first 25 frames of shadows if you tell the game that the specific animation has shadows.
   
• Object: Next are object .SHP files. These include normal structure images and bibs. Object files only tell the game to display one frame of itself at a certain point in time, it is not meant to be an animation. Again there is an order to which the frames should be in so the game displays the correct image at the right time.
  Frame 1 - Normal Image (this image is displayed as the standard non-damages structure image when you first build it.)
  Frame 2 - Damages Image (contains the image of the same structure when damaged at half strength.)
  Frame 3* - Garrison Image (Frame 3 is used for when the structure is garrisoned by infantry units. However for structures that don't normally allow garrisonning, like player structures, usually have a duplicated Frame 2 in this frame.)
  Frame 4** - Debris Image (If the structure is designed to leave behind debris this is the frame that the graphics go in. Structures that don't leave debris omit this frame entirely.)
  Finally, the last 3 or 4 frames (depending on if you have a Frame 4 or not) contains the shadows for each stage. Frame 1 uses the first shadow image while Frame 2 uses the second and so forth.
   
  *Bib object images do not contain this frame at all.
  **You should notice that the debris frame is usually a mess of strange colours, that is because the image is in a different palette to the standard structure one. It is in the palette of the specific theater, hence why structures with debris need every single theater file called for, and not simply to use the global G one.
   
• Overlay: Finally we have Overlay .SHP's, which include Walls. Since Pavement does not exist in RA2/YR I will only cover walls in this section. There actually are not too many third-party downloads of extra overlay .SHP's so you may not have to deal with these much. Overlay files are somewhat a mixture between the two above, it contains multiple images like the Animation, but only displaying one normally like an Object. The best way to look at these is to use examine an existing wall .SHP image. It contains images for every possible corner and straight piece for it as well as damages and shadow frames as normal. Overlays are a bit tricky to add, since they involve ToOverlay= art logic, so I won't be covering them with this tutorial.

You should now be completly familiar with the layout and reasons behind what structures are and what files and graphics make them what they are. I'm sure advanced modders knew all about this from the beginning, but basic tutorials are that get new modders to work hard.