Modifier Areas

Avatar Modifiers #

Avatars behave and look consistently throughout Decentraland as they walk across scenes. However, you can add an AvatarModifierArea to a region of your scene to affect how player avatars behave when they enter that area.

❗Warning
Please limit the amount of AvatarModifierAreas you use in your scene to just a couple. If you use too many of them, it may have a significant impact on performance.

Placing Avatar Modifier Areas #

Add an entity with an AvatarModifierArea component and position this entity by using a Transform component.

const entity = engine.addEntity()

AvatarModifierArea.create(entity, {
  area: Vector3.create(4, 3, 4),
  modifiers: [AvatarModifierType.HIDE_AVATARS],
})

Transform.create(childEntity, {
  position: Vector3.create(8, 0, 8),
})

When creating an AvatarModifierArea component, you must provide the following:

• area: Size of the modifier area
• modifiers: An array listing the modifiers to implement in the area. This property uses values from the AvatarModifierType enum.

The supported modifiers are:

• AvatarModifierType.AMT_HIDE_AVATARS
• AvatarModifierType.AMT_DISABLE_PASSPORTS

All the effects of an AvatarModifierArea only take place within the region of their area. Players return to normal when they walk out of the area.

An AvatarModifierArea affects only players that are inside the area, entering the area doesn’t affect how other players that are outside the area are perceived.

The effects of an AvatarModifierArea are calculated locally for each player. You can have an AvatarModifierArea that is only present in the scene for some of the players and not for others. For example, you could make a “marco polo” game, where only one player in the scene has a modifier area that hides all of the other players. All the other players that don’t have this modifier area in their local version of the scene are able to see each other normally. If the area hides avatars, then the players that don’t have the area in their local version of the scene will see all avatars normally. Even those that experience themselves as hidden. Players that do have the area will experience themselves and all other avatars as affected by the area when they enter it.

📔 Note: Avatar modifier areas are affected by the position and rotation of the Transform component of their host entity, but they’re not affected by the scale.

Hide avatars #

When a player walks into an AvatarModifierArea that has the AvatarModifierType.AMT_HIDE_AVATARS modifier, the player’s avatar stops being rendered. This applies both for the player in 3rd person view, and for when other players walk into the area.

const entity = engine.addEntity()

AvatarModifierArea.create(entity, {
  area: Vector3.create(4, 3, 4),
  modifiers: [AvatarModifierType.AMT_HIDE_AVATARS],
})

Transform.create(childEntity, {
  position: Vector3.create(8, 0, 8),
})

This allows you to replace the default Decentraland avatar with any custom avatar you might want to show in your scene. Note that if you want to see other players with custom avatars, you should handle the syncing of player positions yourself.

Disable Passport Popup #

When a player walks into an AvatarModifierArea that has the AvatarModifierType.AMT_DISABLE_PASSPORTS modifier, clicking on them no longer opens up the passport UI that shows the player bio, inventory, etc.

const entity = engine.addEntity()

AvatarModifierArea.create(entity, {
  area: Vector3.create(4, 3, 4),
  modifiers: [AvatarModifierType.AMT_DISABLE_PASSPORTS],
})

Transform.create(childEntity, {
  position: Vector3.create(8, 0, 8),
})

This is especially useful in games where accidentally opening this UI could interrupt the flow of a game, for example in a multiplayer shooter game.

Camera modifiers #

Players are normally free to switch between first and third person camera by pressing V on the keyboard. Use a CameraModeArea to force the camera mode to either 1st or 3rd person for all players that stand within a specific area in your scene.

const entity = engine.addEntity()

CameraModeArea.create(entity, {
  area: Vector3.create(4, 3, 4),
  mode: CameraType.CT_FIRST_PERSON,
})

If a player’s current camera mode doesn’t match that of the CameraModeArea, they will transition to that camera mode. A toast appears onscreen to clarify that this change is due to the scene. While inside, players can’t change their camera mode. When a player leaves the CameraModeArea, their camera mode is restored to what they had before entering.

Use CameraModeArea in regions where players would have a significantly better experience by using a specific camera mode. For example, first person is ideal if the player needs to click on small object, or third person may be useful for players to notice some entity that your scene has attached over their head. Don’t assume players know how to switch camera modes, many first-time players might not know they have the option, or not remember the key to do it.

📔 Note: Camera modifier areas are affected by the position and rotation of the Transform component of their host entity, but they’re not affected by the scale.

📔 Note: If you overlap multiple camera modifier areas, the last one to be instanced by your scene’s code will take priority over the others.

When creating an CameraModeArea component, you must provide the following:

• area: Size of the modifier area
• cameraMode: Which camera mode to force in this area, from the CameraType enum.

The supported camera modes are:

• CameraType.CT_FIRST_PERSON
• CameraType.CT_THIRD_PERSON

Exclude Avatars #

You can exclude a list of players from being affected by a modifier area by adding their player Ids to an array in the excludeIds property of the modifier area.

This example hides all avatars in an area, except those of players with specific IDs. You could use this for example on a live event, to only show the event hosts on the stage, and hide any other players that jump onto the stage.

const entity = engine.addEntity()

AvatarModifierArea.create(entity, {
  area: Vector3.create(4, 3, 4),
  modifiers: [AvatarModifierType.AMT_HIDE_AVATARS],
  excludeIds: ["0xx1...", "0xx2..."],
})

Transform.create(childEntity, {
  position: Vector3.create(8, 0, 8),
})

📔 Note: Make sure the player IDs are all written with lower-case letters. Use .toLowerCase() if necessary.

Modifier areas run locally on each player’s instance, the list of excluded IDs can be different for each player. In the example below, each player excludes their own ID from a modifier that hides avatars, so that they each view their own avatar and no others.

import { getUserData } from "~system/UserIdentity"

executeTask(async () => {
  let userData = await getUserData()
  if (!userData) return

  const entity = engine.addEntity()

  AvatarModifierArea.create(entity, {
    area: Vector3.create(16, 5, 16),
    modifiers: [AvatarModifierType.AMT_HIDE_AVATARS],
    excludeIds: [userData.userId],
  })

  Transform.create(childEntity, {
    position: Vector3.create(8, 0, 8),
  })
})

❗Warning
If the list of excluded IDs is going to be periodically changed (for example based on players entering or leaving an area), make sure that the list is kept in order. Perform a .sort() on the array, so that the list remains in the same order each time it’s passed. In that way, only the changes to the list are be computed. This can otherwise have a significant impact on the scene’s performance.

  AvatarModifierArea.create(entity, {
    area: Vector3.create(16, 5, 16),
    modifiers: [AvatarModifierType.AMT_HIDE_AVATARS],
    excludeIds: [myAvatarList.sort()],
  })

Debug modifier areas #

It can be tough to know exactly what parts of the scene your modifier areas cover based on the code. Visual feedback helps a lot to confirm that they’re well placed.

To verify the positions of a AvatarModifierArea or a CameraModeArea, give the entity holding it a MeshRenderer component with a box shape, and set the scale to the same size as the area of the modifier area.

📔 Note: Modifier areas aren’t affected by the scale property of the transform, their size is based on their area property.

const entity = engine.addEntity()

AvatarModifierArea.create(entity, {
  area: Vector3.create(8, 3, 8),
  modifiers: [AvatarModifierType.AMT_HIDE_AVATARS],
})

Transform.create(entity, {
  position: Vector3.create(8, 0, 8),
  scale: Vector3.create(8, 3, 8),
})

MeshRenderer.setBox(entity)

To activate the effects of the modifier area, the player’s head or torso should enter the area. It won’t take effect if only the feet of the player are covered. Make sure the player can’t easily evade the area by jumping.

📔 Note: The full area should fit inside the limits of your scene.