Struct CollisionFilter

Namespace: Box3D

Assembly: Box3D.NET.dll

Controls which shapes are allowed to collide with each other.

public readonly record struct CollisionFilter : IEquatable<CollisionFilter>

Implements

IEquatable<CollisionFilter>

Inherited Members

object.Equals(object?)

object.Equals(object?, object?)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object?, object?)

object.ToString()

Examples

Giving a player its own category and letting it collide only with the world and with enemies:

[Flags]
enum Layers : ulong
{
    World  = 1 << 0,
    Player = 1 << 1,
    Enemy  = 1 << 2,
    Debris = 1 << 3,
}

var filter = new CollisionFilter
{
    Categories  = (ulong)Layers.Player,
    CollidesWith = (ulong)(Layers.World | Layers.Enemy),
};

Stopping a ragdoll from colliding with itself, without touching any masks:

var filter = CollisionFilter.Default with { Group = -ragdollIndex };

Remarks

Two shapes collide when each one's Box3D.CollisionFilter.Categories appears in the other's Box3D.CollisionFilter.CollidesWith mask. The test is symmetric: both directions must agree, so making one shape ignore another is enough to disable the pair.

Box3D.CollisionFilter.Group overrides the masks entirely when it is non-zero, which is the cheap way to express "these objects never collide with each other" without spending a category bit on them.

The same filter applies to queries such as ray casts, not only to shape-versus-shape collision.

Constructors

CollisionFilter(ulong, ulong, int): Initializes a new instance of the Box3D.CollisionFilter struct.

Properties

Categories: Gets the categories this shape belongs to. Usually a single bit.
CollidesWith: Gets the categories this shape is willing to collide with.
Default: Gets a filter that belongs to every category and collides with everything.
Group: Gets the collision group. Shapes sharing a negative group never collide; shapes sharing a positive group always collide. Zero has no effect.