what are some general steps to making that happen?
There are only three pieces of software that you really need to make new objects like buildings, and new land objects like the 4 mile x 4 mile tankland objects:
Aces High Terrain Editor
Aces High Object Editor
AC3D Pro
And actually Easycor can make new objects just from a text file, which is absolute alchemy, imho. My hat is off to him.
You could add L3DT to that list, but I've accomplished building and tile creation without having to use L3DT (even though I own the pro license).
For any object:
The easiest way to get started is to convert an existing shape to AC3D from within the Object Editor. Here's the quick and dirty:
1. Pick a shape in the OE shape list, and select it with a mouse click.
2. Click the "Export to Ac3d" button.
3. Close the OE.
4. Go to your Aces High directory, and in the Export folder, you will find the AC3D file (extension .ac), and all of the bitmaps. At this point you'd be neater if you copied this stuff over to a new folder outside of the Aces High directory, but that's not a requirement.
5. Open AC3D, and load the object file.
6. You can push around, reconfigure, and reshape, re-weld, explode, group, hollow out, extrude... Do whatever you want and make the shape the way you want. Note that in the destructible objects, HTC has a 'live' shape and a 'dead' shape. You can play with the dead shapes too.
7. Once you've got the shape down, save it under a new name and close AC3D.
8. Open the bitmaps and change them to what you want, and save it using the naming convention Greebo described in the skins forum sticky. This is a whole other topic, and Greebo covers most of it. I would only add that the Alpha map can be your friend, allowing the atlas textures to come through your object wherever you wanted it to. You want a road through your 2x2 land object? The make sure the path is delineated with polygons in AC3D, make sure it's 'painted' with the road surface, and that it's not Alpha'd out with the alpha map.
9. Go back into AC3D, and load the texture file you just modified.
10. Using AC3D's Texture Coordinate Editor (TCE), select the polys (one or multiple), and apply the textures from your bitmap. Keep doing that until all your polys are painted with the new bitmap. Save and close.
11. Open the AC3D file in Notepad, and double check that the bitmap file names are correct.
12. Open the OE, and select File - Convert Ac3d File. Find your way to your folder, and click on the AC3D file you just worked on. This step creates the SHP and HTX files for your object, and deposits them in the 'userlib' folder in your Aces High III directory.
13. Copy the SHP and HTX files. Go to the directory that holds the terrain you're working on (under the ah3terr folder), and paste these files into the texsrc folder. Your new object is now available for placement in the terrain.
14. Open the TE and the terrain your are working on.
15. Select a point on the terrain where you want your object deposited. Find your object in the list of shapes, highlight it, and click Add. Make sure you accurately set all of the flags in the object properties pop-up. This can do things like make your object inert, make it burn when it blows up, give it an initial hardness, give it field or country ownership, etc.
You can also add your object to another object using the OE.
You might get some errors along the way, however, especially if the bitmap file names are wrong. Also, if you try to add a color to a poly from AC3D's palette, you will get an error when you try to load it in the TE or OE.
Also, it would be worthwhile to learn the architecture of the AC3D file format. It's actually a text file you can open in Notepad. Opening it in Notepad lets you see all the stuff that gets programmed into your object, from the world-object-kid structure, to the "materials", bitmaps, the different flag states, what the dead flags do, even the vertex locations. You can even call up another shape to appear if the object goes to a dead state.
You could create an object from scratch, but for some reason I get errors when I do that. I think it has to do with all of the flags that need to be in there, and materials definitions. I haven't learned enough about it yet to know for sure. But for now, I'm getting some interesting stuff done just with conversions of existing objects.