Modeling Interior Views
The interior view may use up to two 2048x2048 textures and be of up to 50k polygons. Handles, needles, levers etc should all be placed in situ but left as seperate objects to allow for animation. All of these objects may share the main interior material.
The basic structure of a cab is quite similar to a number of different assets. You will have a main mesh with a number of attached sub-meshes, which are arranged using a mesh-table.
The main cab mesh typically consists of the interior walls, roof and floor of the cab, the control desk or stand, all furniture or other static objects visible inside the cab, and also all parts of the locomotive exterior that are visible from inside the cab - e.g. the top of any projecting nose below the cab windows. Remember to consider the sightlines out of rear windows too for visible bodywork panels - the user can move around the cab and rotate the camera to any angle. Users are not restricted to looking forward out of the front windows only.
There are some differences in style between the construction of an interior object and a typical trainz object.
Except in very specific circumstances, there will not be more than one interior object in existence at any time, and that interior is always viewed from very close range - the user is inside it. Because of this, interiors are typically modelled with a high polygon count and with high resolution textures, to give an impressive visual feel. LOD is not used, as the user never gets far enough away from the interior for LOD techniques to have worthwhile benefit.
Trainz lights interior objects differently to map objects like buildings and other scenery - the main illumination is ambient, not directional. (A steam loco does have a directional light coming from the firebox, but a diesel or electric cab typically has no directional light inside, and relies entirely on ambient illumination).
With ambient illumination, effects such as normal and specular mapping do not have much (if any) effect. Because of this, more effort needs to be put into the diffuse texture for a cab interior than would normally be applied to Trainz objects. Drawing or baking shadows and other effects into the diffuse textures is required to produce a nice looking cab interior."
Like locomotives, coaches are comprised of a group of seperate models which are combined in the game as required, though there are some differences.