Player Physics in Decentraland

Apply forces to the player's avatar using the

Physics

API from

@dcl/sdk/ecs

. All physics operations affect the local player only.

Why this skill exists — the Transform mistake

The player's

Transform

(on

engine.PlayerEntity

) is engine-controlled and read-only from scene code. Writing to it via

Transform.getMutable

Transform.createOrReplace

, or direct

.position

.rotation

mutation silently does nothing — the code compiles, the system ticks, no error is thrown, and the avatar never moves.

If your goal is to lift, float, push, knock back, or apply any sustained force to the player, use this skill's
Physics
API. For instant teleports / smooth slides to a specific position, use

movePlayerTo

from

~system/RestrictedActions

(skill:

player-avatar

typescript

// WRONG — has no effect in-world
const t = Transform.getMutable(engine.PlayerEntity)
t.position.y += 0.1  // ignored every frame

// CORRECT — lift the player upward
import { Physics } from '@dcl/sdk/ecs'
import { Vector3 } from '@dcl/sdk/math'
Physics.applyImpulseToPlayer(Vector3.create(0, 50, 0))   // one-shot upward launch
// or, sustained lift / hover:
const lifter = engine.addEntity()
Physics.applyForceToPlayer(lifter, Vector3.create(0, 1, 0), 12)  // continuous upward force
// stop with: Physics.removeForceFromPlayer(lifter)

Impulse (One-Shot Push)

Apply a single instantaneous force with

Physics.applyImpulseToPlayer(direction, magnitude?)

. Direction is auto-normalized when magnitude is passed separately. Multiple calls within the same frame are accumulated. Use for launch pads, jumps, and explosions.

Knockback (Push Away from a Point)

Push the player away from a source position with

Physics.applyKnockbackToPlayer(sourcePos, magnitude, radius?, falloff?)

. Direction is computed automatically from source to player.

KnockbackFalloff Options

Falloff	Behavior
`KnockbackFalloff.CONSTANT`	Same magnitude at any distance within radius (default)
`KnockbackFalloff.LINEAR`	Smooth linear decrease to 0 at the radius edge
`KnockbackFalloff.INVERSE_SQUARE`	Sharp, physically-realistic drop-off

If the player is exactly at the source, they are pushed straight up. A negative magnitude pulls the player toward the point. Same falloff values apply to

applyRepulsionForceToPlayer()

. Prefer

KnockbackFalloff.LINEAR

for most area effects — it feels natural and predictable.

Continuous Force

Apply a persistent directional force identified by an entity (the force "owner"). Multiple forces from different entities stack.

Apply:

Physics.applyForceToPlayer(entity, direction, magnitude?)

Remove:
```
Physics.removeForceFromPlayer(entity)
```

Use with trigger zones for wind tunnels, conveyor belts, and gravity fields.

Timed Force

Apply a force for a fixed duration:

Physics.applyForceToPlayerForDuration(entity, seconds, direction, magnitude?)

. Expires automatically.

Repulsion Force

Continuous push away from a fixed point with distance-based falloff, recalculated each frame:

Physics.applyRepulsionForceToPlayer(entity, position, magnitude, radius)

. The position must be passed explicitly — not read from the entity's Transform automatically. Remove with

Physics.removeForceFromPlayer(entity)

Coordinate Conversion (Local to World Direction)

Convert local direction to world space with

Transform.localToWorldDirection(entity, localDir)

. Use when pushing relative to an entity's orientation (e.g. "forward from this cannon").

Quick Reference

Method	Type	Description
`Physics.applyImpulseToPlayer(dir, mag?)`	One-shot	Instant directional push
`Physics.applyKnockbackToPlayer(pos, mag, radius?, falloff?)`	One-shot	Push away from point
`Physics.applyForceToPlayer(entity, dir, mag?)`	Continuous	Persistent push while active
`Physics.removeForceFromPlayer(entity)`	Control	Stop a continuous force
`Physics.applyForceToPlayerForDuration(entity, secs, dir, mag?)`	Timed	Force that expires automatically
`Physics.applyRepulsionForceToPlayer(entity, pos, mag, radius)`	Continuous	Distance-based push from point
`Transform.localToWorldDirection(entity, dir)`	Utility	Convert local direction to world space

Trigger-zone collider layers — which player fires the trigger

Physics.*

always affects the local player. When you drive forces from a

TriggerArea

, the collider mask decides which avatars fire the callback (verified in test scene

5,5-collider-layers

Mask	Fires for
`ColliderLayer.CL_MAIN_PLAYER`	the local player only
`ColliderLayer.CL_PLAYER`	remote avatars only (NOT the local player)
`CL_PLAYER \| CL_MAIN_PLAYER`	both local and remote
`ColliderLayer.CL_PHYSICS`	never fires for any avatar (targets scene mesh/walls, not characters)

Prefer
CL_MAIN_PLAYER
for player-physics trigger zones. Because the callback then only fires for the local player, you do not need a remote-vs-local guard, and the force is applied to the one avatar it can affect. A launch pad using

CL_PLAYER

alone will NOT fire for the local player (only for remote avatars), so it never launches the person standing on it — a common bug.

If you do use

CL_PLAYER | CL_MAIN_PLAYER

, guard with

result.trigger?.entity === engine.PlayerEntity

—

result.trigger?.entity

is the entity that entered. Note:

result.triggeredEntity

is the trigger area's OWN entity, not the entrant, so comparing it to

PlayerEntity

never distinguishes who entered.

Forces while gliding

While the player is gliding (glider open), forces behave differently:

Continuous forces (
```
applyForceToPlayer
```
,
```
applyForceToPlayerForDuration
```
,
```
applyRepulsionForceToPlayer
```
) are 1.5× stronger — the open glider catches the airflow, so wind zones/currents feel more responsive.
The upward component of a continuous force can lift a gliding player.
```
glidingFallingSpeed
```
(in
```
AvatarLocomotionSettings
```
) only caps descent speed; it does not cancel upward motion, so an angled or vertical current pushes the player along the full force direction. Enables thermal updrafts / wind corridors.
One-shot impulses (
```
applyImpulseToPlayer
```
,
```
applyKnockbackToPlayer
```
) are NOT affected by gliding — identical whether the glider is open or closed.

For full code examples (launch pad, wind tunnel, repulsion field, coordinate conversion), see

{baseDir}/references/physics-patterns.md

player-physics

NPX Install

SKILL.md Content