Skip to main content

CollisionGroup

CollisionGroups indicate like members that do not collide with each other. Use CollisionGroupManager to create CollisionGroups

For example:

Players have collision group "player"

Enemies have collision group "enemy"

Blocks have collision group "ground"

Players don't collide with each other, but enemies and blocks. Likewise, enemies don't collide with each other but collide with players and blocks.

This is done with bitmasking, see the following pseudo-code

PlayerGroup = 0b001 PlayerGroupMask = 0b110

EnemyGroup = 0b010 EnemyGroupMask = 0b101

BlockGroup = 0b100 BlockGroupMask = 0b011

Should Players collide? No because the bitwise mask evaluates to 0 (player1.group & player2.mask) === 0 (0b001 & 0b110) === 0

Should Players and Enemies collide? Yes because the bitwise mask is non-zero (player1.group & enemy1.mask) === 1 (0b001 & 0b101) === 1

Should Players and Blocks collide? Yes because the bitwise mask is non-zero (player1.group & blocks1.mask) === 1 (0b001 & 0b011) === 1

Index

Constructors

Properties

Accessors

Methods

Constructors

constructor

  • new CollisionGroup(name: string, category: number, mask: number): CollisionGroup

  • STOP!!** It is preferred that CollisionGroupManager.create is used to create collision groups unless you know how to construct the proper bitmasks. See https://github.com/excaliburjs/Excalibur/issues/1091 for more info.

    Parameters

    • name: string

      Name of the collision group

    • category: number

      32 bit category for the group, should be a unique power of 2. For example 0b001 or 0b010

    • mask: number

      32 bit mask of category, or ~category generally. For a category of 0b001, the mask would be 0b110

    Returns CollisionGroup

Properties

publicstaticAll

All: CollisionGroup = ...

The All CollisionGroup is a special group that collides with all other groups including itself, it is the default collision group on colliders.

Accessors

publiccategory

  • get category(): number

  • Get the category of the collision group, a 32 bit number which should be a unique power of 2

    Returns number

publicmask

  • get mask(): number

  • Get the mask for this collision group

    Returns number

publicname

  • get name(): string

  • Get the name of the collision group

    Returns string

Methods

publiccanCollide

  • Evaluates whether 2 collision groups can collide

    This means the mask has the same bit set the other category and vice versa

    Parameters

    Returns boolean

publicinvert

  • Inverts the collision group. For example, if before the group specified "players", inverting would specify all groups except players

    Returns CollisionGroup

    CollisionGroup

publictoString

  • toString(): string

  • Returns string

publicstaticcollidesWith

publicstaticcombine

  • Combine collision groups with each other. The new group includes all of the previous groups.

    Parameters

    Returns CollisionGroup