bird.js

export class Bird {
  #app;
  #container;
  #img;
  #state;
  #target = {
    "x": 0,
    "y": 0
  }
  #bird_state = {
    "out": 1,
    "down": 2,
    "adjust": 3,
    "stay": 4,
    "leave": 5
  };
  // out, down, adjust, stay 

  constructor(app) {
    this.#state = this.#bird_state.out; 
    this.#app = app;
    this.#container = new PIXI.Container();
    this.#container.visible = false;
    this.#app.stage.addChild(this.#container);
    const texure = PIXI.Texture.from('smallbird_1.png');
    this.#img = new PIXI.Sprite(texure);
    this.#img.anchor.set(0.5)
    this.#img.scale.set(0.5);
    this.#container.addChild(this.#img);
    this.#container.x = Math.floor(Math.random() * 150) - 150;
    this.#container.y = Math.floor(Math.random() * 300) - 149;
    this.#searchPlace();
  }

  appear(delta) {
    if (this.#state === this.#bird_state.out) {
      this.#state = this.#bird_state.down; 
    }

    switch (this.#state) {
      case this.#bird_state.down:
        this.#moveDown(delta);
        break;
      case this.#bird_state.adjust:
        this.#moveAdjust(delta);
        break;
      default:
        //do nothing;
    }

  }

  #searchPlace() {
    this.#target.x = Math.floor(Math.random() * this.#app.screen.width) + 10;
    this.#target.y = this.#app.screen.height / 2;
  }

  #moveDown(delta) {
    if (this.#target.y + 30 === this.#container.y) {
      this.#state = this.#bird_state.adjust;
    }
    if (((this.#target.y - 30) < this.#container.y + 30) && (this.#container.y < this.#target.y + 30)) {
      this.#container.x += 0.5;
      this.#container.y += 0.5;
    }
    else if (this.#container.y < this.#target.y) {
      this.#container.x += 1;
      this.#container.y += 1;
    }
  }

  #moveAdjust(delta) {
    if (this.#target.y === this.#container.y) {
      this.#state = this.#bird_state.stay;
    }
    this.#container.y -= 0.5;
  }

  visible(visible) {
    this.#container.visible = visible;
  }

  leave() {
  }
}