Sound Hints
Sound hints are used by NPCs to get extra context a sound and how to react to it. There are also hints that are used to mimic a smell, such as an organic corpse.
Sound hints can be produced in Lua using sound.EmitHint
Enumerations¶
Table Key
❌ – Unused by the Engine (Can still be used in Lua)
| Enumeration Name | Bit Number | Default Triggers |
|---|---|---|
| SOUND_NONE | 0 | No Sounds |
| SOUND_COMBAT | 1 | Grenade explosions |
| SOUND_WORLD | 2 | N/A |
| SOUND_PLAYER | 4 | Footsteps |
| SOUND_DANGER | 8 | Props on fire, barrels about to explode, combine rappelling??, Combine Mine triggered, SMG1 grenades, HL2 grenade, Antlion Worker spit, Antlion Guard Charge, Combine Helicopter turret impact location & bomb drop warning, Combine Dropship deploy & turret impact locations, Combine Gunship belly cannon & turret impact locations, Manhacks opening their blades, Rollermine about to self-destruct, Stalker laser impact location, Zombine Grenade, Combine APC moving, in the path of an Airboat |
| SOUND_BULLET_IMPACT | 16 | Bullet holes |
| SOUND_CARCASS ❌ | 32 | UNUSED in Source |
| SOUND_MEAT ❌ | 64 | UNUSED in Source |
| SOUND_GARBAGE ❌ | 128 | UNUSED in Source |
| SOUND_THUMPER | 256 | HL2 Combine Thumper |
| SOUND_BUGBAIT | 512 | Impact Location (Not squeeze!) |
| SOUND_PHYSICS_DANGER | 1024 | N/A |
| SOUND_DANGER_SNIPERONLY | 2048 | N/A (Supposed to scare Combine Snipers) |
| SOUND_MOVE_AWAY | 4096 | N/A |
| SOUND_PLAYER_VEHICLE | 8192 | Airboats |
| SOUND_READINESS_LOW ❌ | 16384 | UNUSED, purpose was for player companion |
| SOUND_READINESS_MEDIUM ❌ | 32768 | UNUSED, purpose was for player companion |
| SOUND_READINESS_HIGH ❌ | 65536 | UNUSED, purpose was for player companion |
| SOUND_CONTEXT_FROM_SNIPER | 1048576 | Combine Sniper aim position |
| SOUND_CONTEXT_GUNFIRE | 2097152 | Added to SOUND_COMBAT, only used by AR2/SMG1/Pistol |
| SOUND_CONTEXT_MORTAR | 4194304 | Mortars from func_tank |
| SOUND_CONTEXT_COMBINE_ONLY | 8388608 | Combine Dropship deployment location, hacked friendly Rollermines, Combine throwing grenades |
| SOUND_CONTEXT_REACT_TO_SOURCE | 16777216 | Made for reacting to the source's origin, not the sound's location: Combine Sniper laser position, Strider minigun impact position, enemy/friendly Rollermines moving, Gunship's belly cannon impact position, Dropship's turret impact position, Hunter's Flechette impact position |
| SOUND_CONTEXT_EXPLOSION | 33554432 | RadiusBlast, Combine ball exploding |
| SOUND_CONTEXT_EXCLUDE_COMBINE | 67108864 | Things that Combine should ignore: Strider Legs, Attacking Rollermine, Hunter Flechette |
| SOUND_CONTEXT_DANGER_APPROACH | 134217728 | Enemy & friendly Rollermines |
| SOUND_CONTEXT_ALLIES_ONLY | 268435456 | Only used for barnacles + does NOT work |
| SOUND_CONTEXT_PLAYER_VEHICLE | 536870912 | Jeep or Jalopy |
Combinations¶
Sound hints can be combined by doing a bit OR operation. There are couple of combinations that the engine uses which are listed below.
Example combination in Lua: bit.bor(SOUND_DANGER, SOUND_CONTEXT_EXCLUDE_COMBINE)
| Enum combination | Default Triggers |
|---|---|
| SOUND_DANGER, SOUND_CONTEXT_EXCLUDE_COMBINE | Flechette impact position, Strider foot impact position |
| SOUND_DANGER, SOUND_CONTEXT_REACT_TO_SOURCE | Combine dropship impact position, Combine gunship turret impact position, Strider minigun impact position |
| SOUND_DANGER, SOUND_CONTEXT_PLAYER_VEHICLE | Detects when a player is driving a Jeep or Jalopy (Not Airboats!) |
| SOUND_DANGER, SOUND_CONTEXT_MORTAR | Combine mortars impact position |