Collide Reference

Definition & Usage

<Collide> name { type [flags] }

This entry indicates that geometry defined at this group level is an invisible collision surface, and is not true geometry. The geometry is used to define the extent of the collision surface. If there is no geometry defined at this level, then a child is searched for with the same collision type specified, and its geometry is used to define the extent of the collision surface (unless the descend flag is given; see below).

Note

It is now deprecated to use <Collide> without descend; it will become the default soon. You should always specify it for best compatibility.

Note

It is not necessary, and in fact some cases it will actually cause problems if you set the transparency value for collision nodes to 0.0. These objects will automatically be invisible in the player if they do not have the keep keyword.

Examples

<Collide> { polyset descend } // considered as a generic wall/mesh barrier
<Collide> door_trigger { plane event intangible descend } // to implement a feature (like a door opening) if the player touches this plane

Collision Types

Plane

The geometry represents an infinite plane. The first polygon found in the group will define the plane.

Polygon

The geometry represents a single polygon. The first polygon is used.

Polyset

The geometry represents a complex shape made up of several polygons.

Note

This collision type should not be overused, as it provides the least optimization benefit.

Sphere

The geometry represents a sphere. The vertices in the group are averaged together to determine the sphere’s center and radius.

Box

The geometry represents a box. The smallest axis-aligned box that will fit around the vertices is used.

InvSphere

The geometry represents an inverse sphere. This is the same as Sphere, with the normal inverted, so that the solid part of an inverse sphere is the entire world outside of it. Note that an inverse sphere is an infinitely large solid with a finite hole cut into it.

Tube

The geometry represents a tube. This is a cylinder-like shape with hemispherical endcaps, sometimes called a capsule or lozenge in other packages. The smallest tube shape that will fit around the vertices is used.

Collision Flags

The flags may be any zero or more of:

event

Throws the name of the <Collide> entry, or the name of the surface if the <Collide> entry has no name, as an event whenever an avatar strikes the solid. This is the default if the <Collide> entry has a name.

intangible

Rather than being a solid collision surface, the defined surface represents a boundary. The name of the surface will be thrown as an event when an avatar crosses into the interior, and name-out will be thrown when an avatar exits.

descend

Each group descended from this node that contains geometry will define a new collision object of the given type. The event name, if any, will also be inherited from the top node and shared among all the collision objects.

Note

This option will soon be the default; it is suggested that it is always specified for most compatibility.

keep

Don’t discard the visible geometry after using it to define a collision surface; create both an invisible collision surface and the visible geometry.

level

Stores a special effective normal with the collision solid that points up, regardless of the actual shape or orientation of the solid. This can be used to allow an avatar to stand on a sloping surface without having a tendency to slide downward.