@rpgjs/physic/dist/index34.js

A deterministic 2D top-down physics library for RPG, sandbox and MMO games

class IceMovement {
  /**
   * Creates an ice-like movement behaviour.
   *
   * @param direction - Initial desired direction (normalized automatically)
   * @param maxSpeed - Maximum speed in units per second
   * @param acceleration - Fraction of the gap closed per second (0-1)
   * @param friction - Fraction of velocity retained per second when stopping (0-1)
   * @param duration - Optional duration in seconds
   */
  constructor(direction, maxSpeed = 4, acceleration = 0.2, friction = 0.08, duration) {
    this.maxSpeed = maxSpeed;
    this.acceleration = acceleration;
    this.friction = friction;
    this.duration = duration;
    this.currentVelocity = { x: 0, y: 0 };
    this.elapsed = 0;
    this.stopped = false;
    const magnitude = Math.hypot(direction.x, direction.y);
    this.targetDirection = magnitude > 0 ? { x: direction.x / magnitude, y: direction.y / magnitude } : { x: 0, y: 0 };
  }
  update(body, dt) {
    if (this.duration !== void 0) {
      this.elapsed += dt;
      if (this.elapsed >= this.duration) {
        this.stopped = true;
      }
    }
    if (!this.stopped) {
      const accelFactor = this.perSecondFactor(this.acceleration, dt);
      const targetVx = this.targetDirection.x * this.maxSpeed;
      const targetVy = this.targetDirection.y * this.maxSpeed;
      this.currentVelocity.x += (targetVx - this.currentVelocity.x) * accelFactor;
      this.currentVelocity.y += (targetVy - this.currentVelocity.y) * accelFactor;
    } else {
      const frictionFactor = this.perSecondFactor(this.friction, dt);
      this.currentVelocity.x *= 1 - frictionFactor;
      this.currentVelocity.y *= 1 - frictionFactor;
    }
    body.setVelocity({
      x: this.currentVelocity.x,
      y: this.currentVelocity.y
    });
  }
  isFinished() {
    if (!this.stopped) {
      return false;
    }
    const speed = Math.hypot(this.currentVelocity.x, this.currentVelocity.y);
    return speed < 0.05;
  }
  stop() {
    this.stopped = true;
  }
  resume() {
    this.stopped = false;
  }
  setTargetDirection(direction) {
    const magnitude = Math.hypot(direction.x, direction.y);
    this.targetDirection.x = magnitude > 0 ? direction.x / magnitude : 0;
    this.targetDirection.y = magnitude > 0 ? direction.y / magnitude : 0;
    this.stopped = false;
  }
  setParameters(maxSpeed, acceleration, friction) {
    if (maxSpeed !== void 0) {
      this.maxSpeed = maxSpeed;
    }
    if (acceleration !== void 0) {
      this.acceleration = acceleration;
    }
    if (friction !== void 0) {
      this.friction = friction;
    }
  }
  perSecondFactor(value, dt) {
    const clamped = Math.max(0, Math.min(1, value));
    if (dt <= 0) {
      return clamped;
    }
    return 1 - Math.pow(1 - clamped, dt);
  }
}
export {
  IceMovement
};
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