17. Developing OR Content

Open Rails already has some own development tools and is defining and developing other ones. A path editor is available within TrackViewer under the Tools button in the main menu window. An editor for timetable mode is also available under the Tools button. Route editor and consist editor are in an advanced stage of development and may already be tested. You can read about and download the consist editor here . You can read about and download the TSRE5 route editor at this link

IT is of course already possible to develop OR content (rolling stock, routes, 3D objects, activities) using the tools used to develop MSTS content, thanks to the high compatibility that OR has with MSTS. Below, some of the advantages of OR-specific content are described.

17.1. Rolling Stock

  • OR is able to display shapes with many more polygons than MSTS. Shapes with more than 100.000 polys have been developed and displayed without problems.

  • Thanks to the additional physics description parameters, a much more realistic behavior of the rolling stock is achieved.

  • 3D cabs add realism.

  • OR graphics renders the results of the rolling stock developers at higher resolution.

  • Rolling stock running on superelevated track improves gaming experience.

17.2. Routes

  • Routes are displayed in higher resolution.

  • Extended viewing distance yields much more realism.

  • Double overhead wire increases the realism of electrified routes.

  • Built-in triphase overhead electric line.

  • Extended signaling features provide more realistic signal behavior.

  • Widescreen and hi-res loading screen.

17.3. Activities

  • Timetable mode is a new activity type available only in Open Rails that allows for development of timetable based gaming sessions.

  • By using the dispatcher monitor window, the dispatcher HUD, and the ability to switch the camera to any AI train, the player can more closely monitor and control the execution of conventional activities.

  • Extended AI shunting greatly increases the interactions between trains.

  • New OR-specific additions to activity (.act) files enhance activities.

17.4. Parameters and Tokens

The parameters used in content files have been mentioned throughout this manual for:

Content Type

File Extension

locomotive

eng

wagon or non-powered vehicle

wag

activity

act

cab view

cvf

consist

con

train service

srv

train traffic

trf

signal configuration

sigcfg.dat

signal scripts

sigscr.dat

sound management

sms

world tile

w

3D model

s, gltf, glb

train timetable

timetable-or

The complete list is very extensive and is documented in an online spreadsheet at tinyurl.com/or-parameters-excel.

Since this is a spreadsheet with many rows, you can restrict your view to relevant rows using the filters at the top of each column.

17.5. Testing and Debugging Tools

As listed here, a rich and powerful set of analysis tools eases the testing and debugging of content under development.

17.6. 3D shape files

In addition to the .s file format used in MSTS, Open Rails is able to read the glTF format model files. However there are some conceptual differences between the two formats that the content developers need to be aware of when creating such files. One of the important specification constraints must be noted, \(+Z\) is the forward direction in glTF format, as opposed to .s, where the forward is \(-Z\).

17.6.1. Textures

The texture format can be PNG, JPG or DDS. The MSFT_texture_dds extension must be used for referencing a DDS texture; it is not just a drop-in file replacement as for the .s files. For final game content try to avoid using PNG and JPG formats at least for the base, emissive and specular textures, because as sRGB types they can only be loaded in two passes; the .NET built-in loader is unable to declare sRGB surface format at load time, and the whole pixel data must be copied a second time. PNG and JPG formats also lack the ability to store mipmaps.

The RGB channels of the base, emissive and specular color textures are in sRGB color space. The alpha channels and any other textures are in linear space.

Instead of the night texture set, the authors can use an emissive texture for night illumination, creating a bloom or glow effect. The emissive texture display can be made to switch on-off automatically at day-to-night transitions if specified in the material:

"extras": { "OPENRAILS_material_day_night_switch": true },

(This setting also affects the IBL lights assigned to a material, see below.)

The max value of the emissive strength is 1.0 in the core standard, but sometimes a bigger glow is needed to remain distinctly visible during the day. (LED panels, etc…) The KHR_materials_emissive_strength. extension can be used to achieve any desired strength.

"extensions": { "KHR_materials_emissive_strength": { "emissiveStrength": 5.0 },

Seasonal textures (like “Snow”) are managed via the KHR_materials_variants extension. A primitive can have multiple materials, each mapped to one or more “variants”. The appropriate variant (e.g. “Snow”) will be activated at load time.

17.6.2. Animations

The animation driving array is in seconds, unlike in .s files, which use frame numbers. Authors can create any number of frames, even with unequal time intervals between them, as the software does not rely on a fixed frame count. Instead, Open Rails precisely interpolates the pose for any required moment in time, even if there is no keyframe assigned to that specific moment. So e.g. for a 8-notched throttle controller one can skip all the intermediate frames and define only the first (at 0 second) and last one (at 8 seconds), it will still work. Looped animations can have any duration and will be treated as a single continuous loop regardless of length.

Two types of animation are supported by Open Rails. Predefined animations are designated with the “animations” “name” attributes. The parent-child relations of the defined animations or the nodes they target are irrelevant in glTF. A node will not be animated simply because it is a child of another animated node. Instead an animation can have multiple target nodes via its multiple “channels”.

The other supported animation type is the node-animation. Such “nodes” are to be marked with the syntax:

"extras": { "OPENRAILS_animation_name": "WHEELS1" },

This will mark the location for Open Rails where to engage its built-in animation logic when needed. The traditional naming pattern applies here, and a node should not be both part of a predefined animation and also marked for node-animation. (Note, the nodes “name” attributes are not used for anything, unlike in s.)

17.6.3. Level-Of-Detail

LOD-s can be defined either as internals via the MSFT_lod extension, or externals by creating multiple gltf files and adding the suffixes of pattern <name>_LOD01.gltf, <name>_LOD02.gltf, etc… The _LOD00 suffix for LOD 0 is optional. The author may still define the displaying criteria in the root node of the LOD 0, as described in the extension, using a line like:

"extras": { "MSFT_screencoverage": [ 0.2, 0.05, 0.001 ] },

In the prior case, for internal LOD-s, the author needs to define the root nodes of the various LOD-s in the root node of the LOD 0. E.g. if node 0 is the root of LOD 0, then to declare node 1 for LOD 1 and node 2 for LOD 2 as their root nodes, looks like this:

"extensions": { "MSFT_lod": { "ids": [ 1, 2 ] } },

(Note for all extensions, the usual extension usage criteria applies, specifically the important one is the requirement to register the extension used into the “extensionsUsed” array of the gltf.)

17.6.4. Lights

Active light sources can be attached to a gltf file as in the KHR_lights_punctual extension. Or even a light-only gltf can be created and used in a W file:

{
"asset": { "version": "2.0" },
"extensionsUsed": [ "KHR_lights_punctual" ],
"scenes": [ { "nodes": [0] } ],
"nodes": [ { "translation": [0, 5, 0], "rotation": [-0.7071, 0, 0, 0.7071], "extensions": { "KHR_lights_punctual": { "light": 0 } } } ],
"extensions": { "KHR_lights_punctual": { "lights": [ { "type": "spot", "range": 500.0, "color": [1.0, 0.9, 0.8], "intensity": 50.0, "spot": { "outerConeAngle": 1.5 } } ] } }
}

These lights are bound to a node, and the nodes can also be set to follow the day-night cycle. By applying the following extra, the whole node will become invisible during daytime, including the attached light, mesh and all further subnodes:

"extras": { "OPENRAILS_node_day_night_switch": true },

It is possible to inject own image based lighting (IBL) to an object via the EXT_lights_image_based extension. Although it allows only to define a model-wide IBL, Open Rails allows to limit its effect to a single material instead (requires the IBL not to be assigned to the whole “scene”):

"extras": { "OPENRAILS_material_image_based_light": 0 },

It is useful to use an own IBL for interiors and cabs, because the bilt-in night IBL is optimized for outside night illumination, and it may be too dark for the inside. A diffuse IBL definition using spherical harmonics looks like below. AI-s can help in generating such coefficients.

"extensions": {
  "EXT_lights_image_based": {
    "lights": [
      { "intensity": 1.0, "irradianceCoefficients": [
        [1.250, 1.050, 0.750], [0.000, 0.000, 0.000], [-0.450, -0.380, -0.250],
        [0.000, 0.000, 0.000], [0.030, 0.025, 0.015], [0.015, 0.012, 0.008],
        [0.060, 0.050, 0.030], [0.015, 0.012, 0.008], [0.030, 0.025, 0.015] ]
      }
    ]
  }
},

17.7. Open Rails Best Practices

17.7.1. Polys vs. Draw Calls – What’s Important

Poly counts are still important in Open Rails software, but with newer video cards they’re much less important than in the early days of MSTS. What does remain important to both environments are Draw Calls.

A Draw Call occurs when the CPU sends a block of data to the Video Card. Each model in view, plus terrain, will evoke one or more Draw Calls per frame (i.e., a frame rate of 60/second means all of the draw calls needed to display a scene are repeated 60 times a second). Given the large number of models displayed in any scene and a reasonable frame rate, the total number of Draw Calls per second creates a very large demand on the CPU. Open Rails software will adjust the frame rate according to the number of required Draw Calls. For example, if your CPU can handle 60,000 Draw Calls per second and the scene in view requires 1000 Draw Calls, your frame rate per second will be 60. For the same CPU, if the scene requires 2000 Draw Calls, your frame rate per second will be 30. Newer design / faster CPU’s can do more Draw Calls per second than older design / slower CPU’s.

Generally speaking, each Draw Call sends one or more polygon meshes for each occurrence of a texture file for a model (and usually more when there are multiple material types). What this means in practice is if you have a model that uses two texture files and there are three instances of that model in view there will be six draw calls – once for each of the models (3 in view) times once for each texture file (2 files used), results in six Draw Calls. As an aid to performance Open Rails will examine a scene and will issue Draw Calls for only the models that are visible. As you rotate the camera, other models will come into view and some that were in view will leave the scene, resulting in a variable number of Draw Calls, all of which will affect the frame rate.

Model builders are advised that the best performance will result by not mixing different material types in a texture file as well as using the fewest number of texture files as is practical.

17.8. Support

Support can be requested on the OR forum on http://www.elvastower.com/forums.

The OR development team, within the limits of its possibilities, is willing to support contents developers.