There is no correct way to make collision objects for the Torque engine. It all depends on how your programmer wants to implement collision detection. Several games used this engine and they all used different collision schemes. Different collision schemes can be different for different shapes as well. Some shapes use simple sphere collision that is derived from the bounding box, some have custom-built collision shapes. Vehicles tend to have custom collision shapes.
Custom collision shapes can be created by assigning a negative detail number to the shape and creating a corresponding detail marker. Shapes with negative numbers will export but not draw. Because Maya does not allow dashes ("-") in object names, underscores ("_") must be used.
The Torque Game Engine presently uses detail markers named Collision_# with the mesh shapes named Col_#. The shapes must be convex hulls (no concave surfaces).
Here are some of the naming conventions:
Keep the detail meshes as low in polygon count as possible, because collision can be processor intensive. Vehicles are limited to ONE collision mesh for the collision shape.
1. Open simpleShapeBase.mb.
2. Duplicate simpleShape128 with the input graph. Rename the new shape Col_1 and set its subdivisionsAxis and subdivisionsHeight to 6.
3. Open Outliner (Window > Outliner).
4. Expand base01. Select detail2 and duplicate it. Rename the new detail marker Collision_1.
5. Save the scene file as simpleShapeCollision.mb.
6. Export this shape. It will now have a collision mesh.
The easiest way to test the collision is to replace an existing shape in the game. For example, you can export a shape called bush1.dts and replace the one that exists in the demo (make sure you rename the old bush1.dts and have your texture in the same directory). Drop in the demo, and you can crash into and bounce off of the shape you just made.