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Top-down movement

TopDownMovementBehavior drives X/Y (or configured plane) locomotion in WASM. Write $topDownMovement each frame with moveX, moveY, and optional faceX / faceY for twin-stick aiming. When faceMovement is true, the runtime rotates toward velocity; leave it false when a separate aim vector or Shooter2DBehavior owns facing.

Minimal example​

website/snippets/behaviors/catalog/top-down.ts:

import { TopDownMovementBehavior } from '@zylem/game-lib/behavior';

const topDown = mover.use(TopDownMovementBehavior, {
  moveSpeed: 8,
  faceMovement: true,
});

mover.onUpdate(({ inputs }) => {
  mover.$topDownMovement.moveX = inputs.p1.axes.Horizontal.value;
  mover.$topDownMovement.moveY = inputs.p1.axes.Vertical.value;
  mover.$topDownMovement.faceX = inputs.p1.axes.SecondaryHorizontal.value;
  mover.$topDownMovement.faceY = inputs.p1.axes.SecondaryVertical.value;
});

Handle​

  • getFacingAngle() — radians, also stored on topDownMovementState.facingAngle for shooters.

Variations​

  • Pair with Shooter2DBehavior and TopDownShooterCoordinator for move + aim + fire in one call.
  • getEntityFacingAngle2D falls back to body rotation or cached 2D angle when composing custom fire logic.

Pitfalls​

  • Requires spawn and behavior system tick before $topDownMovement exists (same as other WASM behaviors).
  • Do not manually set entity rotation every frame if faceMovement or top-down state already drives facing.

API reference​