@rpgjs/physic/dist/index38.js

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

class Oscillate {
  /**
   * Creates an oscillating movement.
   *
   * @param direction - Base direction (will be normalized)
   * @param amplitude - Maximum displacement from the anchor position
   * @param period - Duration of a full cycle in seconds
   * @param type - Oscillation pattern
   * @param duration - Total life time in seconds (undefined for infinite)
   */
  constructor(direction, amplitude, period, type = "sine", duration) {
    this.amplitude = amplitude;
    this.period = period;
    this.type = type;
    this.duration = duration;
    this.elapsed = 0;
    this.anchor = null;
    const magnitude = Math.hypot(direction.x, direction.y);
    this.direction = magnitude > 0 ? { x: direction.x / magnitude, y: direction.y / magnitude } : { x: 1, y: 0 };
  }
  update(body, dt) {
    if (this.anchor === null) {
      this.anchor = { x: body.position.x, y: body.position.y };
    }
    this.elapsed += dt;
    if (this.duration !== void 0 && this.elapsed >= this.duration) {
      body.setVelocity({ x: 0, y: 0 });
      return;
    }
    const cycle = this.period <= 0 ? 0 : this.elapsed % this.period / this.period;
    const frequency = this.period > 0 ? 2 * Math.PI / this.period : 0;
    let velocityScale;
    switch (this.type) {
      case "sine":
        velocityScale = Math.cos(cycle * Math.PI * 2) * frequency * this.amplitude;
        break;
      case "circular":
        velocityScale = Math.cos(cycle * Math.PI * 2) * frequency * this.amplitude;
        break;
      case "linear":
        const halfCycle = cycle < 0.5;
        velocityScale = (halfCycle ? 1 : -1) * (2 * this.amplitude) / (this.period / 2);
        break;
      default:
        velocityScale = 0;
    }
    const vx = this.direction.x * velocityScale;
    const vy = this.direction.y * velocityScale;
    if (this.type === "circular") {
      const perpendicularScale = -Math.sin(cycle * Math.PI * 2) * frequency * this.amplitude;
      body.setVelocity({
        x: vx - this.direction.y * perpendicularScale,
        y: vy + this.direction.x * perpendicularScale
      });
    } else {
      body.setVelocity({ x: vx, y: vy });
    }
  }
  isFinished() {
    return this.duration !== void 0 && this.elapsed >= this.duration;
  }
  reset() {
    this.elapsed = 0;
    this.anchor = null;
  }
}
export {
  Oscillate
};
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