basdon.net aviation server

Articles > Internal docs > SAMP internals

SAMP internals

Everything on this page is about SA-MP 0.3.7-R4

• Client console commands
• Vehicle categories (client)
• Vehicle damage status
• Player position and server streaming
• Packet priority, reliability, ordering channel
• Misc

Client console commands

See samp.dll+690D0.

• /audiomsg - toggles whether messages are printed when audio streams are played
• /cmpstat - does absolutely nothing
• /ctd - toggles camera target debug (what is the effect?)
• /dl - toggles debug labels on vehicles
• /fontsize <size> - changes chat window's font size
• /fpslimit <limit> - set fps limit of the game. only has effect if "Frame limiter" in game settings is enabled.
• /headmove - toggles whether other players' character head will move to the direction they're looking at
• /hudscalefix - toggles a fix that ensures the minimap radar is a circle on widescreen resolutions
• /interior - prints the current game interior
• /logurls - toggles whether messages are printend when files are downloaded. file downloading is leftover code that is not usable.
• /mem - prints the game's streaming memory limit
• /nametagstatus - toggles whether the "hourglass" icon is shown next to players' nametags when they are paused
• /pagesize <size> - sets amount of lines that the chat window shows on screen
• /q - alias of /quit
• /quit - quit the game
• /rcon <command> - sends rcon commands to the server
• /rs [comment] - saves current position, depending on your state:
  • when on foot, saves x,y,z,facingAngle ; comment in Documents\GTA San Andreas User Files\SAMP\rawpositions.txt
  • when in car, saves model,x,y,z,heading,col1,col2 ; comment in rawvehicles.txt in your game folder (this seems like an oversight and was probably supposed to be in User Files too)
• /save [comment] - saves current position in Documents\GTA San Andreas User Files\SAMP\savedpositions.txt formatted as a AddPlayerClass or AddStaticVehicle function call, depending on your state.
• /testdw - send test values to the death message list (death message list may be hidden with F9)
• /timestamp - toggles whether to show timestamp before chat messages
• /togobjlight - seems unused

• /player_skin <skinid>
• /set_weather <weatherid>
• /set_time <hour> <minute>
• /v <model> - alias of /vehicle
• /vehicle <modelid> - spawns a vehicle next to you. model value is unchecked, so this will crash the client if it's invalid
• /vsel - opens vehicle selection UI. Use the JUMP/SPRINT keys to select the model and ENTER VEHICLE key to spawn

Vehicle Categories (client)

Some vehicle things are handled differently by the client depending on the category of the vehicle. The category of a vehicle is determined at runtime by its vtable. SAMP defines following categories:

• 0: other, which effectively is: trailer/monstertruck(+dune/dumper)/quadbike⁽¹⁾
• 1: automobile (vtable 0x871120)
• 2: motorcycle (vtable 0x871360)
• 3: heli (vtable 0x871680)
• 4: boat (vtable 0x8721A0)
• 5: plane (vtable 0x871948)
• 6: bike (vtable 0x871528)
• 7: train (vtable 0x872370)

Notes

⁽¹⁾ vehicles with a vtable that isn't one of the explicitely checked values are put in category 0. Besides all trailers, this also (maybe unexpectedly) includes Dumper, Monster, Monster A, Monster B, Quadbike, Dune. This is because the Dumper, Dune and all Monster vehicles are instances of CMonsterTruck and the Quadbike has its own unique CQuadBike class.

Vehicle damage status

See https://basdon.github.io/documented-samp-pawn-api/main.xml#Appendix_Vehicle_Damage_Status for an overview of vehicle support, behavior, and some quirks.

Server receiving damage from client

Server ignores damage status updates if it's not coming from the driver of the vehicle, otherwise it's applied and synced unconditionally and OnVehicleDamageStatusUpdate is invoked.

Client receiving damage from server

Behavior depends on the vehicle model it's being applied to, see also Vehicle categories. Most import to take into account: Dumper, Monster, Monster A, Monster B, Quadbike, Dune are categorized as "unknown", meaning none of their damage gets synced. The bumper may get damaged in the driver's game (or tires of a quad bike), but none of the other players will see any damage to that vehicle.

Client applies tire damage at CSampVehicle::ApplyVehicleDamageTires(char) with following behavior:

• for CHeli/CPlane/CBmx/CBoat/CTrain/Unknown: nop
• for CAutomobile: apply to CAutomobile.m_damageManager.wheel[]
• for CBike: apply to CBike.m_acWheelDamageState[]

Client applies other damage at CSampVehicle::ApplyVehicleDamagePanelsDoorsLights(int,int,char) with following behavior:

• for CBike/CHeli/CPlane/CBmx/CBoat/CTrain/Unknown: nop
• for CAutomobile/CPlane:
  • if not all values are 0:
    • apply panels doors lights to CAutomobile::m_damageManager
    • call CAutomobile::mCC() (seems to apply damage status things, spawn flying components if things are detached, ...)
  • if all values are 0: call CAutomobile::Fix⁽¹⁾⁽³⁾

Notes

⁽¹⁾ while CPlane inherits from CAutomobile, it overrides the Fix method yet SAMP still calls the base CAutomobile::Fix for CPlane instances. This is what causes the 'ghost door' effect⁽⁶⁾ on some planes after doing RepairVehicle()⁽²⁾ or updating damage status to 0 on planes.

For comparison, MTA dispatches to specific overridden methods based on the vehicle's model info:

if (pModelInfo->IsCar() || pModelInfo->IsMonsterTruck() || pModelInfo->IsTrailer())
    dwFunc = FUNC_CAutomobile__Fix(3);
else if (pModelInfo->IsPlane())
    dwFunc = FUNC_CPlane__Fix(3);
else if (pModelInfo->IsHeli())
    dwFunc = FUNC_CHeli__Fix(3);
else if (pModelInfo->IsBike())
    dwFunc = FUNC_CBike_Fix(3);

Source: https://github.com/multitheftauto/mtasa-blue/blob/bb0b32cb90f3379853fb9eab0a651caabd837d6f/Client/game_sa/CVehicleSA.cpp#L1120 .

It also defines FUNC_CQuadBike__Fix⁽³⁾, yet that is not used in the above.

⁽²⁾ RepairVehicle(vehicleid) is implemented in SAMP by doing SetVehicleHealth(vehicleid, 1000.0); UpdateVehicleDamageStatus(vehicleid, 0, 0, 0, 0);.

⁽³⁾ Implementations of the Fix proc:

• CAutomobile::Fix does the following:
  • CAutomobile::m_damageManager.reset()
  • if (!(CVehicle::pHandlingData->uiModelFlags & 0x100(4))) m_damageManager.door[2] = door[3] = door[4] = door[5] = 4(5);
  • clump stuff
  • CVehicle::m_nVehicleFlags[1] &= 0xFE; (clears bIsDamaged)
  • matrix stuff
  • m_damageManager.wheel[0] = wheel[1] = wheel[2] = wheel[3] = 0; (seems unnecessary as m_damageManager.reset() already did this)
  • reset bouncing panels^{[citation needed]}
• CPlane::Fix does the following:
  • CAutomobile::m_damageManager.reset()
  • if (!(CVehicle::pHandlingData->uiModelFlags & 0x100(4))) m_damageManager.door[2] = door[3] = door[4] = door[5] = 4(5);
  • CVehicle::m_nVehicleFlags[1] &= 0xFE; (clears bIsDamaged)
• CHeli::Fix does the following:
  • CAutomobile::m_damageManager.reset()
  • CVehicle::m_nVehicleFlags[1] &= 0xFE; (clears bIsDamaged)
• CBike::Fix does the following:
  • CVehicle::m_nVehicleFlags[1] &= 0xFE; (clears bIsDamaged)
  • CBike::m_cDamageFlags &= 0xBF; (unknown)
  • CBike::m_acWheelDamageState[0] = CBike::m_acWheelDamageState[1] = 0;
• CQuadBike::Fix does the following:
  • CAutomobile::m_damageManager.reset()
  • m_damageManager.door[2] = door[3] = door[4] = door[5] = 4(5);
  • clump stuff
  • m_damageManager.wheel[0] = wheel[1] = wheel[2] = wheel[3] = 0; (seems unnecessary as m_damageManager.reset() already did this)
  • CVehicle::m_nVehicleFlags[1] &= 0xFE; (clears bIsDamaged)

⁽⁴⁾ uiModelFlags mask 0x100 means NO_DOORS, as per data/handling.cfg comments (field modelFlags (af)).

⁽⁵⁾ a damagemanager door value of 4 means that the door is removed/detached.

⁽⁶⁾ https://basdon.github.io/documented-samp-pawn-api/main.xml#Appendix_Vehicle_Damage_Status_planeghostdoors

Player position and server streaming

Player position and streaming is processed when:

• receiving spectating sync data from that player
• receiving passenger sync data from that player
• receiving driver sync data from that player
• receiving onfoot sync data from that player
• PlayerSpectateVehicle is called
• PlayerSpectatePlayer is called
• PutPlayerInVehicle is called

First it will unconditionally store the passed position into the player's data.

Then it checks if the player has an expected location after being teleported (which gets set when calling either of: PlayerSpectateVehicle / PlayerSpectatePlayer / PutPlayerInVehicle / SetVehiclePos (only for the driver of the vehicle*)). If the expected position has been set less than 5000ms ago (not configurable), streaming will be aborted if the player is not yet within stream_distance of it.

*there is some inconsistent/unexpected behavior regarding this, it seems that tracking of who is driver of the vehicle isn't always reset correctly (it seems to be relying on receiving onuccupied sync packets). This results in the following behavior: when teleporting a vehicle with SetVehiclePos to a location further than the configured stream distance from the last driver of that vehicle, that player may experience a 5 second period where streaming may not be processed.

When triggered by receiving sync data, it will first check if enough time has passed since the last time streaming was processed (stream_rate console/server.cfg variable) and skip if this is not the case.

When triggered by the script functions, streaming is processed immediately. Note that this completely bypasses the stream rate check, so it is possible that next streaming processing will occur much earlier than what the normal stream_rate delay would be from this moment.

After streaming, the checkpoint and race checkpoint are tested. If one is active and the player is now inside and was not before, the appropriate callback is called (OnPlayerEnterCheckpoint/OnPlayerEnterRaceCheckpoint). If one is active and the player is not inside, and was before, the "Leave" callback is called. Note that state seems to be reset when disabling a checkpoint, so disabling the checkpoint while a player is in it will not trigger the "Leave" callback.

Streaming

Player markers

Player markers are streamed if the global setting for marker mode is not set to 0. Markers are updated every 2500ms (not configurable). Markers are included of players who are in the same virtual world, are not in state "none" or "spectating", not NPCs, and within the distance limit if marker mode is "streamed".

Vehicles

A vehicle is streamed in when it exists, has field_7A set to 1, is in the same virtual world, is not of model FREIFLAT or STREAKC (those are never streamed to the client, the client always automatically creates 3 carriages when the train engine vehicle is created), and is within stream_distance.

If that is not the case and the vehicle is still streamed in, it will be streamed out.

(note that no more vehicles will be streamed in if a client already has 700 vehicles streamed in)

Trivia: when it decides to stream in a vehicle, the function to stream in the vehicle checks the stream distance condition again even though we know it already passed that check. This doesn't happen for any of the other elements being streamed in this section.

Players

A player is streamed in when they exist, are not in state "none" or "spectating", are in the same virtual world, and is within stream_distance (calculated from the player position, except if the player is a passenger of a vehicle because then the position of the vehicle is used).

If that is not the case and the player is still streamed in, they will be streamed out.

(note that no more players will be streamed in if a client already has 200 players streamed in)

TextLabels

A 3D text label is streamed in when it is in use and, if attached to a player or vehicle: if that player or vehicle is streamed in, if not attached: if the label is in the same virtual world and the player is within its draw distance.

If that is not the case and the text label is still streamed in, it will be streamed out.

Pickups

A pickup is streamed in when it is in use, is in the same virtual world, and within stream_distance.

If that is not the case and the pickup is still streamed in, it will be streamed out.

Actors

An actor is streamed in when they are in use, are in the same virtual world, and within stream_distance.

If that is not the case and the actor is still streamed in, they will be streamed out.

Packet priority, reliability, ordering channel

Misc

Scoreboard: the client periodically requests an update for player scores & pings (rpc 155). The server only responds if it has been more than 2000ms since the last request.

Legacy pickup rpcs: the server can receive rpc 97 which reads a single 2-byte pickup id, to which the server will broadcast rpc 151 to all clients (containing that 2-byte pickup id). Clients receiving rpc 151 will read a 1-byte value and delete a pickup identified by that value. It doesn't seem like clients ever send rpc 97.

rpc 102: when sent by the client (no payload), the server will respond (if player is rcon admin) with 196 bytes of raknet stats (assumption) (stats of UNASSIGNED_PLAYER_ID, so does this mean global stats?).

This article has been accessed 249 time(s).
Main page Article index