Collision groups

Collision groups define what types of collision can collide with each other. For example, an entity using COLLISION_GROUP_DEBRIS will only collide with the world and not any dynamic entities.

When the game tests a pair collision groups, the lower collision group is always first in the checks. All collision groups can touch triggers.

List

These are defined in public/const.h:

Todo: List collision groups and interactions from and

Name	Value	Solid to players	Solid to bullets	Solid to projectiles	Solid to physics	Solid to world	Description
COLLISION_GROUP_NONE	0	Yes	Yes	Yes	Yes	Yes	Default collision group
COLLISION_GROUP_DEBRIS	1	No	No	No	No	Yes	Typically used for small objects that shouldn't interfere with gameplay. Will not touch triggers unless the trigger has the Debris spawnflag enabled. Collides with COLLISION_GROUP_PUSHAWAY.
COLLISION_GROUP_DEBRIS_TRIGGER	2	No	No	No	No	Yes	Despite the name, this is the same as COLLISION_GROUP_DEBRIS, but does not collide with COLLISION_GROUP_PUSHAWAY.
COLLISION_GROUP_INTERACTIVE_DEBRIS	3	No Yes	No	No	No	Yes	Same as above, but doesn't collide with other COLLISION_GROUP_INTERACTIVE_DEBRIS. VPhysics props that are asleep will be converted to COLLISION_GROUP_DEBRIS
COLLISION_GROUP_INTERACTIVE	4	Yes	Yes	Yes	Yes	Yes	Does not collide with debris. Gibs from models not flagged as debris are set to this group. func_door and func_door_rotating use this if set to ignore debris.
COLLISION_GROUP_PLAYER	5	Yes	Yes	Yes Depends	Yes	Yes	Used by players, but NOT for movement collision. Does not collide with COLLISION_GROUP_PASSABLE_DOOR. Except in , this will not collide with COLLISION_GROUP_PUSHAWAY. In , does not collide with grenade, engineer buildings (except teleporters), combat object groups and tank groups.
COLLISION_GROUP_BREAKABLE_GLASS	6	Yes	Yes	Yes	Yes	Yes	Used by func_breakable_surf. Does not collide with other COLLISION_GROUP_BREAKABLE_GLASS. NPCs ignore these for weapon LOS checks. In , crossbow bolts will go through this.
COLLISION_GROUP_VEHICLE	7	Yes	Yes	Yes	Yes	Yes	Used by driveable vehicles. Always collides against COLLISION_GROUP_VEHICLE_CLIP
COLLISION_GROUP_PLAYER_MOVEMENT	8	Yes Depends	Yes	Yes No	Yes	Yes	Used by player movement collision tests. Behaves identically to COLLISION_GROUP_PLAYER. Except in , this will not collide with COLLISION_GROUP_PUSHAWAY. In , will not collide with projectile, rocket, grenade, combat object and tank groups. Engineer buildings (except teleporters), players (if tf_avoidteammates is 1), bot_npc_archer, bot_npc_decoy, func_croc, func_forcefield, func_respawnroom, func_respawnroomvisualizer, tf_target_dummy will check for team-specific contents (usually the entity's team number decide these) to consider collision. passtime_ball will not collide with this, but _ballplayertoucher (spawned by the ball) will.
COLLISION_GROUP_NPC	9	Yes	Yes	Yes	Yes	Yes	Used by NPCs. Always collides with COLLISION_GROUP_DOOR_BLOCKER
COLLISION_GROUP_IN_VEHICLE	10	No	No	No	No	No	Set on players/NPCs which enter a vehicle.
COLLISION_GROUP_WEAPON	11	No	Yes	Yes Depends	Yes	Yes	Used by weapons, including when dropped. In , does not collide with rockets.
COLLISION_GROUP_VEHICLE_CLIP	12	No	No	No	No	No	Used by func_vehicleclip. Ony collides with COLLISION_GROUP_VEHICLE.
COLLISION_GROUP_PROJECTILE	13	Yes No	Yes	No Depends	Yes	Yes	Set on projectiles. Does not collide with other projectiles. In , rockets and grenades have their own collision groups. This will not collide with rockets, however it does collide with grenades!
COLLISION_GROUP_DOOR_BLOCKER	14	No	No	No Depends	No	No	Used by prop_door_rotating (creates a entity_blocker entity). Only supposed to collide with COLLISION_GROUP_NPC. In , also collides with rockets, grenades and certain projectiles. Todo: Investigate the projectile behavior more
COLLISION_GROUP_PASSABLE_DOOR	15	No	Yes	Yes	Yes	Yes	Used by func_door and func_door_rotating when the non-solid spawnflag is set.
COLLISION_GROUP_DISSOLVING	16	No	Yes	No	Yes	Yes	Set on entities dissolved with env_entity_dissolver. Only collides with COLLISION_GROUP_NONE.
COLLISION_GROUP_PUSHAWAY	17	No Yes	Yes	Yes	Yes	Yes	Set by func_physbox_multiplayer. Also set by prop_physics_multiplayer on spawn and when awakened, if sv_turbophysics is enabled. Collides with COLLISION_GROUP_DEBRIS. Used to push away props from the player in and .
COLLISION_GROUP_NPC_ACTOR	18	Yes No	Yes	Yes	Yes	Yes	Set on NPCs when they are potentially stuck in a player. Behaves identically to COLLISION_GROUP_NPC if not testing against COLLISION_GROUP_PLAYER.
COLLISION_GROUP_NPC_SCRIPTED	19	Yes	Yes	Yes	Yes	Yes	Set on NPCs playing out a scripted_sequence, if NPC collisions are set to be disabled. In , does not collide with other COLLISION_GROUP_NPC_SCRIPTED

Extended collision groups in Team Fortress 2 only:

Name	Value	Solid to players	Solid to hitscan	Solid to projectiles	Solid to physics	Solid to world	Description
TFCOLLISION_GROUP_GRENADES	20	No	Yes	N/A Depends	Yes	Yes	Set by grenade projectiles. Does not collide with other TFCOLLISIONGROUP_GRENADES and rockets.
TFCOLLISION_GROUP_OBJECT	21	N/A Depends	Yes	Yes	Yes	Yes	Set by Engineer buildings except teleporters. Uses team-specific contents on players.
TFCOLLISION_GROUP_OBJECT_SOLIDTOPLAYERMOVEMENT	22	Yes	Yes	Yes	Yes	Yes	Set on teleporters.
TFCOLLISION_GROUP_COMBATOBJECT	23	No	Yes	Yes	Yes	Yes	Set by placed sappers and the medigun shield (entity_medigun_shield).
TFCOLLISION_GROUP_ROCKETS	24	No	Yes	No	Yes	Yes	Set by rocket projectiles. Collides with COLLISION_GROUP_PLAYER but not player movement. Does not collide with weapons or any projectiles except rockets. Collides with medigun shields.
TFCOLLISION_GROUP_RESPAWNROOMS	25	Yes	No	No	No	No	Used by func_respawnroom and func_respawnroomvisualizer.
TFCOLLISION_GROUP_PUMPKIN_BOMB	26	No	Yes	Yes	Yes	Yes	Set by team-assigned tf_pumpkin_bombs.
TFCOLLISION_GROUP_ROCKET_BUT_NOT_WITH_OTHER_ROCKETS	27	No	Yes	No	Yes	Yes	Set by arrows and the Short Circuit's secondary attack (tf_projectile_mechanicalarmorb). Same as TFCOLLISION_GROUP_ROCKETS but doesn't collide with other rockets.

Extended collision groups in Garry's Mod:

Name	Value	Solid to players	Solid to hitscan	Solid to projectiles	Solid to physics	Solid to world	Description
COLLISION_GROUP_WORLD	20	[Todo] Unknown	[Todo] Unknown	[Todo] Unknown	[Todo] Unknown	[Todo] Unknown	Doesn't collide with players/props

Extended collision groups in Portal 2:

Name	Value	Solid to players	Solid to hitscan	Solid to projectiles	Solid to physics	Solid to world	Description
COLLISION_GROUP_PZ_CLIP	20	Yes	Yes	Yes	Yes	Yes
COLLISION_GROUP_CAMERA_SOLID	21	No	No	No	No	No	Solid only to the camera's test trace.
COLLISION_GROUP_PLACEMENT_SOLID	22	No	No	No	No	No	Solid only to the placement tool's test trace.
COLLISION_GROUP_PLAYER_HELD	23	No	Yes	Yes	Yes	Yes	Held objects that shouldn't collide with players.
COLLISION_GROUP_WEIGHTED_CUBE	24	Yes	Yes	Yes	Yes	Yes	Cubes need a collision group that acts roughly like COLLISION_GROUP_NONE but doesn't collide with debris or interactive.
COLLISION_GROUP_DEBRIS_BLOCK_PROJECTILE	25	No	No	No	No	No	Supposedly only collides with bullets, but does not.