In this page:

Overview

A Collision Group is a physical property that defines which objects can collide with each other and which cannot. For example, most static props have the collision group "static". If we look at the table, we can see that "static" collides with objects in the following groups: "base_shell", "ragdoll", "mov_control", "attached", "mc_ignore", and "actor_ragdoll". That means that if you want your newly created dynamic barrel with physics to collide with a static prop, it needs to have one of those groups assigned as a collision_group.

Interaction Table of Collision Groups

	static	base shell	additional shell	ragdoll	no collisions shell	trigger	mov control	attached	mc ignore	actor ragdoll	obstacle	mov control ghost	no collisions but ff	only triggers	force_field	Internal name	What for	Notes

	static	base shell	additional shell	ragdoll	trigger	mov control	attached	mc ignore	actor ragdoll	obstacle	mov control ghost	no collisions but ff	only triggers	force_field	Internal name	What for	Notes
static		+		+		+	+	+	+						static	Static and superstatic.
base shell	+	+		+	+	+	+	+						+	base_shell	Dynamic.	Compared with static collides with static and restrictors but not with ragdoll.
additional shell						+									add_shell	Hit-capsules.	Collides only with capsules entities.
ragdoll	+	+		+	+		+	+						+	ragdoll_shell	Ragdolls (except an actor).	Similarly to the base shell.
no collisions shell															no_collision_shell	Without collision.
trigger		+		+		+	+	+					+		trigger	Restrictors (except obstacles).	Similarly to the static but collides only with triggers.
mov control	+	+	+		+	+	+			+	+				mc_default	Capsules entities.	Compared with base_shell collides with hit-capsules, obstacles, mov control ghost but doesn't collide with ragdolls and mc_ignore.
attached	+	+		+	+	+	+	+							attached	Attached objects.	Similarly to the base shell but by "cheat" doesn't collide with its parent.
mc ignore	+	+		+	+		+								mc_ignore	Dynamic without collision with capsules entities.
actor ragdoll	+								+					+	actor_ragdoll_shell	Actor's ragdoll.	Collides only with the static, force-fields, and with itself.
obstacle						+									obstacle	Obstacles.	Collides only with capsules entities.
mov control ghost						+					+				mc_non_collidable	Ghosts.	Collides only with capsules entities and the same mov control ghost.
no collisions but ff														+	no_clg_but_ff	Objects for force-fields.	Collides only with force-fields.
only triggers					+										only_triggers	Objects for restrictors.	Collides only with restrictors.
force_field		+		+					+			+			force_field	Force-fields.	Collides with dynamic, ragdolls (include actor's ragdoll), and with objects for force fields.

Examples of a Collision Group Interaction

Base shell and Static Prop.

Static and Static Prop.