dcl-regenesislabs/camera-control

Camera Control in Decentraland

Authoring split

CameraModeArea and VirtualCamera are supported in main-entities.ts — both static-by-nature components belong there. MainCamera is NOT supported because it lives on the reserved engine.CameraEntity; activate a virtual camera at runtime in src/index.ts.

VirtualCamera.lookAtEntity accepts an entity name in main-entities.ts (resolved to an Entity ID at build time, same as Transform.parent).

// main-entities.ts
cinematic_cam: {
  components: {
    Transform: {
      position: { x: 12, y: 4, z: 8 },
      rotation: { x: 0, y: 0.7071, z: 0, w: 0.7071 }
    },
    VirtualCamera: {
      defaultTransition: { transitionMode: { $case: 'time', time: 2 } },
      lookAtEntity: 'shopkeeper'  // name of another entity in this file
    }
  }
},
first_person_zone: {
  components: {
    Transform: { position: { x: 8, y: 1, z: 8 } },
    CameraModeArea: {
      area: { x: 16, y: 2, z: 16 },
      mode: 0  // CameraType.CT_FIRST_PERSON
    }
  }
}

Activate the cinematic camera at runtime:

// src/index.ts
import { engine, MainCamera } from '@dcl/sdk/ecs'

export function main() {
  const cam = engine.getEntityOrNullByName('cinematic_cam')
  if (cam) MainCamera.createOrReplace(engine.CameraEntity, { virtualCameraEntity: cam })
}

The reserved engine.CameraEntity and engine.PlayerEntity are engine-managed and have no representation in main-entities.ts.

CameraType values for CameraModeArea.mode

| value | enum | meaning | |---|---|---| | 0 | CT_FIRST_PERSON | Force first-person inside the zone | | 1 | CT_THIRD_PERSON | Force third-person inside the zone | | 2 | CT_CINEMATIC | Force cinematic camera inside the zone |

Reading Camera State

Access the camera's current position and rotation via the reserved engine.CameraEntity:

import { engine, Transform } from '@dcl/sdk/ecs'

function trackCamera() {
  if (!Transform.has(engine.CameraEntity)) return

  const cameraTransform = Transform.get(engine.CameraEntity)
  console.log('Camera position:', cameraTransform.position)
  console.log('Camera rotation:', cameraTransform.rotation)
}

engine.addSystem(trackCamera)

Camera Mode Detection

Check whether the player is in first-person or third-person:

import { engine, CameraMode, CameraType } from '@dcl/sdk/ecs'

function checkCameraMode() {
  if (!CameraMode.has(engine.CameraEntity)) return

  const cameraMode = CameraMode.get(engine.CameraEntity)
  if (cameraMode.mode === CameraType.CT_FIRST_PERSON) {
    console.log('First person camera')
  } else if (cameraMode.mode === CameraType.CT_THIRD_PERSON) {
    console.log('Third person camera')
  }
}

engine.addSystem(checkCameraMode)

Camera Mode Values

CameraType.CT_FIRST_PERSON  // First-person view
CameraType.CT_THIRD_PERSON  // Third-person view (default)

CameraModeArea (Force Camera in a Region)

Force a specific camera mode when the player enters an area:

import { engine, Transform, CameraModeArea, CameraType } from '@dcl/sdk/ecs'
import { Vector3 } from '@dcl/sdk/math'

const fpArea = engine.addEntity()
Transform.create(fpArea, { position: Vector3.create(8, 1.5, 8) })

CameraModeArea.create(fpArea, {
  area: Vector3.create(6, 4, 6),         // 6x4x6 meter box
  mode: CameraType.CT_FIRST_PERSON       // Force first-person inside
})

When the player leaves the area, the camera reverts to their preferred mode.

VirtualCamera (Cinematic Cameras)

Create scripted camera positions for cutscenes or special views:

import { engine, Transform, VirtualCamera, MainCamera } from '@dcl/sdk/ecs'
import { Vector3, Quaternion } from '@dcl/sdk/math'

const cinematicCam = engine.addEntity()
Transform.create(cinematicCam, {
  position: Vector3.create(8, 5, 2),
  rotation: Quaternion.fromEulerDegrees(-20, 0, 0)
})

VirtualCamera.create(cinematicCam, {
  defaultTransition: {
    transitionMode: VirtualCamera.Transition.Speed(1.0)
  }
})

// Activate the virtual camera
MainCamera.getMutable(engine.CameraEntity).virtualCameraEntity = cinematicCam

// Return to normal camera
MainCamera.getMutable(engine.CameraEntity).virtualCameraEntity = undefined

Transition Modes

VirtualCamera.Transition.Speed(1.0)  // Speed-based smooth transition
VirtualCamera.Transition.Time(2)     // Time-based transition (2 seconds)

Look-At Target

Make the virtual camera track an entity:

const target = engine.addEntity()
Transform.create(target, { position: Vector3.create(8, 1, 8) })

VirtualCamera.create(cinematicCam, {
  lookAtEntity: target,
  defaultTransition: {
    transitionMode: VirtualCamera.Transition.Speed(2.0)
  }
})

// Activate
MainCamera.getMutable(engine.CameraEntity).virtualCameraEntity = cinematicCam

Tracking Camera Position

Poll camera position each frame for camera-triggered events:

import { engine, Transform } from '@dcl/sdk/ecs'
import { Vector3 } from '@dcl/sdk/math'

let lastNotifiedZone = ''

function cameraZoneSystem() {
  if (!Transform.has(engine.CameraEntity)) return

  const camPos = Transform.get(engine.CameraEntity).position
  let currentZone = ''

  if (camPos.y > 10) {
    currentZone = 'sky'
  } else if (camPos.x < 4) {
    currentZone = 'west'
  } else {
    currentZone = 'center'
  }

  if (currentZone !== lastNotifiedZone) {
    lastNotifiedZone = currentZone
    console.log('Camera entered zone:', currentZone)
  }
}

engine.addSystem(cameraZoneSystem)

Common Patterns

Camera-Triggered Events

Use the camera position to trigger actions when the player looks at a specific area:

function cameraLookTrigger() {
  const camTransform = Transform.get(engine.CameraEntity)
  const targetPos = Vector3.create(8, 2, 8)
  const distance = Vector3.distance(camTransform.position, targetPos)

  if (distance < 5) {
    // Player is close — check if camera is pointing at target
    // Use raycasting for precise look detection (see add-interactivity skill)
  }
}

engine.addSystem(cameraLookTrigger)

Following an NPC

Move camera to track an NPC by updating a VirtualCamera's Transform:

function followNpcCamera(dt: number) {
  const npcPos = Transform.get(npcEntity).position
  const camTransform = Transform.getMutable(cinematicCam)

  // Position camera behind and above the NPC
  camTransform.position = Vector3.create(
    npcPos.x - 2,
    npcPos.y + 3,
    npcPos.z - 2
  )
}

engine.addSystem(followNpcCamera)

Freezing player during cutscenes? Combine VirtualCamera with InputModifier from the advanced-input skill to prevent player movement during cinematic sequences.

Camera vs Colliders (preventing camera-through-wall)

In third-person mode the player's camera can slide through walls if the wall's collider mask doesn't include CL_POINTER. The camera uses the pointer collider mask for occlusion checks — not CL_PHYSICS. Set both masks on walls and architecture that the camera should bounce off:

// main-entities.ts
wall: {
  components: {
    Transform: { position: { x: 8, y: 1.5, z: 16 } },
    GltfContainer: {
      src: 'models/wall.glb',
      visibleMeshesCollisionMask: 3   // CL_PHYSICS | CL_POINTER
    }
  }
}

For GLBs that ship with invisible collider meshes (Creator Hub asset packs), set invisibleMeshesCollisionMask: 3 instead. Default of CL_PHYSICS only would let the camera pass through.

Best Practices

• Only one VirtualCamera should be active at a time.
• Use CameraModeArea to force first-person in tight indoor spaces.
• Keep transition speeds between 0.5 and 3.0 for comfortable camera movement.
• Read camera state via engine.CameraEntity — never try to write to it directly.
• For look-at detection, combine camera position with raycasting (see add-interactivity skill).
• Camera control is read-only outside of VirtualCamera and CameraModeArea — you cannot directly move the player's camera.