Colliders

A collider gives a body its shape. Add one (or several) alongside a Rigid Body. Several colliders on one entity combine into a compound shape.

Shapes

Collider	Shape	Key fields
Box	A box	Half Extent (half-size per axis)
Sphere	A ball	Radius
Capsule	A pill, along local Y	Radius, Half Height
Cylinder	A flat-ended cylinder	Radius, Half Height, Cap Radius
Mesh	A mesh’s geometry	Mesh, Convex
Terrain	A terrain heightmap	(needs a Terrain on the same entity)

A capsule’s total height is 2 × (Half Height + Radius); a cylinder’s is 2 × Half Height, with Cap Radius rounding the rim (set it to a small value to avoid sharp-edge stuck contacts).

Every collider also carries the following.

• Translation Offset places the shape relative to the entity. Box, capsule, cylinder, and mesh colliders add a Rotation Offset too (a 90° rotation lays a capsule on its side); sphere and terrain have no rotation.
• Physics Material is the surface’s friction and bounce, see Materials & Destruction. When unset, the rigid body’s *Override fields apply.
• Is Trigger makes it a non-solid trigger volume, see Collisions & Triggers.
• Affects Navigation sets whether the shape is baked into navmeshes.

Mesh colliders, convex or concave

A Mesh collider builds its shape one of two ways.

• Convex (Convex on) is a convex hull of the mesh. Valid on dynamic bodies. Use it for props. If Mesh is left empty, it falls back to the entity’s Static Mesh component.
• Concave (Convex off) is the exact triangle mesh. Valid only on static or kinematic bodies. Use it for level geometry.

Prefer a primitive shape (box, sphere, capsule) over a mesh collider wherever you can. They are far cheaper to simulate.