Common Messages

A reference for the messages plugins use most. Every id and class name here is taken from the CS2 .proto files (usermessages.proto, cstrike15_usermessages.proto, netmessages.proto, networkbasetypes.proto, cs_gameevents.proto); the fields are listed with their .proto types so you can pick the right accessor (Setting fields).

Valve changes these between updates. When a message does not do what this page says, compare with the current .proto in SteamTracking/Protobufs.

Text

Before sending text yourself, look at the helpers: CBasePlayerController has PrintToChat, PrintToCenter, PrintToCenterAlert and PrintToConsole, all built on UM_TextMsg, and CCSPlayerController::PrintToCenterHtml shows HTML in the centre of the screen.

UM_TextMsg's dest is where the text appears. The values the SDK's print helpers use:

The text goes in param — the first element is the message (or a localisation token), the rest are its arguments.

void* pMsg = NET_MSG_ALLOC_BY_ID(UM_TextMsg);
g_pSource2ModNetworkMessages->SetUInt32(pMsg, "dest", 3);
g_pSource2ModNetworkMessages->AddString(pMsg, "param", "Round starts in 10 seconds");
NET_MSG_SEND_PLAYERS(pMsg, UM_TextMsg, ~0ull);
NET_MSG_FREE(pMsg);

NetMessage msg = Source2ModNetworkMessages.AllocateNetMessageByID(UM_TextMsg);
Source2ModNetworkMessages.SetUInt32(msg, "dest", 3);
Source2ModNetworkMessages.AddString(msg, "param", "Round starts in 10 seconds");

int everybody[2];
PlayerMask_All(everybody);
Source2ModNetworkMessages.SendMessageToPlayers(msg, UM_TextMsg, everybody);
Source2ModNetworkMessages.DeallocateNetMessage(msg);

Screen effects

Note the differences between the two families: UM_Fade's colour is a packed fixed32 (SetUInt32), CS_UM_Fade's is a CMsgRGBA (SetColor); UM_Shake has amplitude, CS_UM_Shake has local_amplitude. For shakes, command 0 starts one — the sample plugin's sample_shake uses UM_Shake, FUNPLAY's slap uses CS_UM_Shake.

// A red flash, CS_UM_Fade.
void* pMsg = NET_MSG_ALLOC_BY_ID(CS_UM_Fade);
g_pSource2ModNetworkMessages->SetInt32(pMsg, "duration", 200);
g_pSource2ModNetworkMessages->SetInt32(pMsg, "hold_time", 100);
g_pSource2ModNetworkMessages->SetInt32(pMsg, "flags", 0x0001);
g_pSource2ModNetworkMessages->SetColor(pMsg, "clr", Color(255, 0, 0, 128));
NET_MSG_SEND(pMsg, CS_UM_Fade, slot);
NET_MSG_FREE(pMsg);

// A red flash, CS_UM_Fade.
NetMessage msg = Source2ModNetworkMessages.AllocateNetMessageByID(CS_UM_Fade);
Source2ModNetworkMessages.SetInt32(msg, "duration", 200);
Source2ModNetworkMessages.SetInt32(msg, "hold_time", 100);
Source2ModNetworkMessages.SetInt32(msg, "flags", 0x0001);
int red[4] = { 255, 0, 0, 128 };
Source2ModNetworkMessages.SetColor(msg, "clr", red);
Source2ModNetworkMessages.SendMessage(msg, CS_UM_Fade, slot);
Source2ModNetworkMessages.DeallocateNetMessage(msg);

The flags, duration and hold_time of the fade messages follow the Source engine's screen-fade conventions; test the values on a client before relying on them.

Sounds

For playing and filtering sounds, use ISource2ModSounds — SOUND_EMIT_FROM_ENTITY and HOOK_SOUND handle GE_SosStartSoundEvent decoded, which is far easier than building or picking apart the message yourself. See ISource2ModSounds.

HUD and player state (CS2)

FUNPLAY's Core re-sends CS_UM_ServerRankRevealAll on player_connect_full, round_start and from a timer: the client-side reveal is time-limited and cleared on map change. Do not send it every tick — spamming it makes the client scoreboard glitch.

Engine messages

// Ask a client for a cvar; the answer arrives as clc_RespondCvarValue with the same cookie.
void* pMsg = NET_MSG_ALLOC_BY_ID(svc_GetCvarValue);
g_pSource2ModNetworkMessages->SetInt32(pMsg, "cookie", ++g_iCookie);
g_pSource2ModNetworkMessages->SetString(pMsg, "cvar_name", "cl_interp_ratio");
NET_MSG_SEND(pMsg, svc_GetCvarValue, slot);
NET_MSG_FREE(pMsg);

HOOK_CLIENT_MESSAGE([](CPlayerSlot slot, int messageid, void* msg) -> Action
{
    if (messageid == clc_RespondCvarValue)
    {
        int cookie = g_pSource2ModNetworkMessages->GetInt32(msg, "cookie");
        std::string value = g_pSource2ModNetworkMessages->GetString(msg, "value");
        // ... match the cookie to the request ...
    }
    return Action::Ignore;
});

int g_iCookie;

// Ask a client for a cvar; the answer arrives as clc_RespondCvarValue with the same cookie.
NetMessage msg = Source2ModNetworkMessages.AllocateNetMessageByID(svc_GetCvarValue);
Source2ModNetworkMessages.SetInt32(msg, "cookie", ++g_iCookie);
Source2ModNetworkMessages.SetString(msg, "cvar_name", "cl_interp_ratio");
Source2ModNetworkMessages.SendMessage(msg, svc_GetCvarValue, slot);
Source2ModNetworkMessages.DeallocateNetMessage(msg);

// in OnPluginStart()
Source2ModNetworkMessages.HookClientMessage(OnClientMessage);

public Source2ModAction OnClientMessage(CPlayerSlot slot, int messageId, NetMessage msg)
{
    if (messageId == clc_RespondCvarValue)
    {
        int cookie = Source2ModNetworkMessages.GetInt32(msg, "cookie");
        char value[128];
        Source2ModNetworkMessages.GetString(msg, "value", value, sizeof(value));
        // ... match the cookie to the request ...
    }
    return Action_Ignore;
}

Where the ids come from

The .pb.h headers declare plain enums, usable directly as the int id; the SDK's enum class versions live in source2mod/schema/entity/enums/ and need a static_cast<int>. Scripts get all of these ids as plain constants from source2mod/netmessage_ids.inc, which source2mod/api includes.