/** Separate the last server pose from the pose currently drawn on screen. */
export function updateRemotePlayer(previous, packet, instant = false) {
  const preserve = previous && !instant;
  const targetYaw = packet.yaw ?? 0;
  return {
    ...packet,
    position: preserve ? previous.position : [...packet.position],
    target: [...packet.position],
    yaw: preserve ? previous.yaw : targetYaw,
    targetYaw,
  };
}

export function smoothRemotePlayer(player, blend) {
  for (let axis = 0; axis < 3; axis++)
    player.position[axis] +=
      (player.target[axis] - player.position[axis]) * blend;
  // Follow the shortest arc, including when server angles cross ±π or 2π.
  const delta = player.targetYaw - player.yaw;
  player.yaw += Math.atan2(Math.sin(delta), Math.cos(delta)) * blend;
}