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VR-Link API Documentation for HLA Evolved
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VR-Link API Documentation for HLA Evolved
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The f18 program simulates a simple HLA or DIS vehicle.
By default, that vehicle is an F/A18, flying in a circle, just off the coast of California, USA, but you can control the entity type, location and route.
f18 generates predictable HLA entity update messages (or DIS entity state PDUs), so it is a useful tool for debugging applications that receive and interpret these messages. It can also fire munitions and react to detonations.
The f18 syntax is:
f18 -h
f18 [options...]
To exit f18, press q followed by Enter or Return.
The following table summarizes f18's command-line options.
| f18 Command-Line Options | |
|---|---|
| Option | Description |
| Protocol Independent Options | |
| -a ID | For DIS, sets the second component of the entity ID to ID. By default, the entity ID is 1:2:1, however if you want to run multiple f18s at once, each needs a unique entity ID.For HLA specifies an entity ID. |
| -d seconds | Set the delay (in seconds) between the time f18 receives a detonation interaction (or PDU), and the time it broadcasts its final message and exits. |
| -D algorithm | Specifes the dead reckoning algorithm, where algorithm can be:
|
| -h | Displays a summary of command-line options, then exits. |
| -H degrees | Specifies the initial heading of the f18, in degrees. |
| -l file | Loads the specified MTL configuration file. |
| -L x,y,z | Specifies the initial position, as in topographic coordinates. |
| -M markings | Specifies the markings. |
| -n notify_level | Specifies the notification level for warnings. |
| -O lat,long | Specifies the reference latitude and longitude for the topographic coordinate system. |
| -r radius | Specifies the turn radius of the f18, in meters. Setting the radius to 0.0 causes the f18 to move in a straight line. |
| -s mps | Specifies the initial speed of the f18, in meters per second. |
| -T type | Specifies the entity type, as a string of the form: kind:domain:country:category:subcategory:specific:extra |
| -W x,y,z | Specifies the initial position in geocentric coordinates. |
| HLA Only Options | |
| (-f | –fomMapperLib) libname | |
| Specifies a FOM Mapper library name. | |
| –fomMapperInitData data | |
| Specifies FOM Mapper initialization data, if required. | |
| –rprFomVersion version_number | |
| Specifies the RPR FOM version. (0.5, 0.7, 0.8, 1.0, 2.0006, 2.0014, or 2.0017) | |
| -F FED_file | Specifies the FED file. Default: federation_name.fed. |
| -N name | Specifies the HLA object name. |
| -n federate_name | Specifies the name of the federate. |
| -x ex-name | Sets the federation execution name. Default: . |
| DIS Only Options | |
| -A address | Specifies the default destination IP address for outgoing PDUs. |
| -I | Use asynchronous IO. |
| -P portnum | Specifies the UDP port. Default: 3000. |
| –recvBufferSize size | Specifies the receive buffer size. |
| –sendBufferSize size | Specifies the send buffer size. |
| –siteId ID | Specifies the site ID. |
| -S address | Subscribes to the specified multicast addresses. Multiple -Ss can appear on a command line. Multicast is not supported on all platforms. |
| –mcastTtl ttl | Specifies the multicast time to live. This is the number of routers that a message can pass through. |
| -V version | Specifies the DIS protocol version contained in outgoing PDUs, where the version can be 4, 5,6 or 6. |
| -x ex-name | Specifies the exercise ID for DIS. Default: 1. |
By default, f18 loads the configuration file f18.mtl, if it exists in the current directory. This file sets many of the f18's default parameters, including notify level, dead-reckoning algorithm, and initial heading, position, and speed.
To change default parameters:
You can rebuild the f18 program or create a new application based on f18 that does not use a configuration file.
To write a variation of f18 that does not use a configuration file, remove the initMtl() call.
You can also specify a different configuration file in your code, at the DtcLoadLispFile() function call.
To cause the f18 to fire at another entity, press Enter or Return.
If other entities exist in the exercise, f18 issues a fire message directed at the closest one. Though there is no tracked munition, f18 issues a detonate message three seconds later to indicate that the target was hit.
To change the delay, edit the munitionFlightTime parameter in the f18.mtl file.
The f18 reacts to detonation PDUs or RPR FOM detonation interactions. If a detonation occurs within the lethalDetonationRange, or if the detonation result is entity impact or entity proximate, the f18 is destroyed. Updates reflect a damage state of DamageDestroyed for a period of destroyedToFinalDelay seconds, at which point the entity leaves the exercise and f18 exits.
LethalDetonationRange defaults to 20 meters, and destroyedToFinalDelay defaults to zero. You can change these parameters in f18.mtl.
The value of the timeStampType flag in f18.mtl determines whether absolute or relative timestamps are used in f18's outgoing state update messages. The flag defaults to relative (0), but can be set to absolute (1). When the timeStampType is absolute, f18 dead-reckons remote entities based on their absolute timestamps, when applicable. Absolute timestamping should be used only when the local machine's clock is synchronized with the clock being used by other applications in the exercise for their absolute timestamps.
For more information about timestamps, please see 2.7.6 Timestamps.
The f18 example has a source file called config.cxx that shows how you can configure VR-Link to use a modified FOM. It shows how you can instruct VR-Link to represent position on the network as Z, Y, X, rather than X, Y, Z. For this purpose, we use a new attribute of the BaseEntity object class called ReversePosition instead of the default Position attribute, and a new parameter of the WeaponFire interaction class called ReverseFiringLocation instead of the default FiringLocation.
By default, this functionality is #ifdef'd out. But if you include the definition REVERSE=1 on your make line, when building f18, for example:
it will be compiled in. If you want to try this out, remember to modify the .fed file to reflect the expected changes before running the executable.
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