Here's what I've found out about Wall Constructions so far.
Wall Constructions consist of a tileset of individual models (visual resources) with the following naming convention:
(Width)_(Tileset name)_(Height)_(Walltype)_(Length)_(Variant)Wall Pieces
Naming the wall pieces correctly is very important so here's a breakdown of the naming convention:(Width)
"#m" where "#" is the width in meters. All units are in meters, same as in Blender. This and the height are just here to indicate the dimensions at a glance.
Again just cosmetic, but the convention seems to be "Race_Type_Variant" if any of those are applicable. Variant is a letter used to distinguish tilesets of the same race and type.(Height)
"#H" where "#" is the height in meters.(Walltype)
There are 6 different types of walls distinguished by this value:
At least 1 E-Wall is required to place the wall construction.
See image below for orientation and pivot point placement in Blender. These are important.(Length)
This number is not just symbolic. It determines the physical distance reserved for this wall piece. A typical straight wall segment will have length 4, and a double segment will have length 8, but this is not required. When building a straight wall, the first piece that appears will be that with the smallest length, and these pieces are summed into larger pieces as the wall is extended. Any number up to 10 seems to be allowed: it reads this number with a decimal point after the first digit. The space allotted seems to be accurate to at least two decimal places. Here is a wall segment of length 133 (1.33 m):
See image below for example lengths. L-Walls are usually the length of 1 wall segment plus half its width.(Variant)
A, B, C, etc. This denotes alternative models of the same piece. These are what get switched between with Ctrl + scrollwheel.
Here are some examples of proper orientation in Blender:
Note the orientation of the free end of the E-Wall. In all cases, the pivot point or origin must be placed on the ground and in the position given by this picture. If your object is rotated incorrectly, you will need to move its vertices to the correct position. Rotating the whole object, at least in Blender, doesn't work.Physics Resources
To by included in a tileset, there must also exist a .bullet physics resource with the same name for each wall piece. I'm running an old version of Blender so I don't know how to export these, but here are some options that may work for you:
1. If your geometry is similar to that of an existing model, you can borrow physics resources from that. 05m_Workerhouse_A and 05m_WoodenHouse_A have very basic physics resources that could work in many situations.
2. It looks like Maya can export .bullet files natively
3. Newer versions of Blender may be able to use this plugin
.Compiling the tileset
To put all the wall pieces into a tileset, you need to make a new wall construction. Find one in the root templates menu, right click it, and select "Create new from selected". Give it a name, usually (Width)_(Tileset name)_(Height). Then under the "Tile Set" option, click the box with the ellipsis, then click the button that appears on the right.
This takes you to the "Choose TileSetPieces" window. In the Resource Manager, select all the visual resources you want to include in your tileset (Ctrl + click), then click add in the "Choose TileSetPieces" window. If they are named correctly and each has a physics resource, they should appear in this window. Click "OK", then "Create" and you should have a new Wall Construction.Exporting models from Blender
In Blender 2.49 (and I assume newer versions), you can export to COLLADA 1.4 (.dae). You can then use Norbyte's Converter App
to convert this into a .gr2 file.