CollisionMask
CollisionMask = readonly
CollisionLayerHandle[] | {except: readonlyCollisionLayerHandle[]; }
The layers a body meets: a list of layers, every layer but those
except lists, or every layer where a declaration leaves it out. A
pair touches only when each one’s mask holds the other’s layer, the
rule Rapier and PlayCanvas use; Godot passes a pair when either mask
holds the other’s.