跟踪子弹效果

assets/Scene/Bullet_Tracking/Bullet_Tracking.ts

@@ -0,0 +1,57 @@
+const { ccclass, property } = cc._decorator;
+
+@ccclass
+export default class Bullet_Tracking extends cc.Component {
+  @property(cc.Node)
+  launch_btn: cc.Node = null;
+
+  @property(cc.Node)
+  bullet: cc.Node = null;
+
+  @property(cc.Node)
+  target: cc.Node = null;
+
+  onLoad() {
+    this.node.on(cc.Node.EventType.TOUCH_MOVE, this.touchMoveEvent, this);
+  }
+
+  touchMoveEvent(evt: cc.Event.EventTouch) {
+    this.target.x += evt.getDeltaX();
+    this.target.y += evt.getDeltaY();
+  }
+
+  fireFlag: boolean = false;
+  fire() {
+    this.bullet.getComponent(cc.Sprite).enabled = true;
+    this.bullet.getChildByName('boom').active = false;
+    this.bullet.setPosition(this.launch_btn.position);
+    this.bullet.active = true;
+    this.fireFlag = true;
+  }
+
+  hitTheTarget() {
+    this.fireFlag = false;
+    this.bullet.getComponent(cc.Sprite).enabled = false;
+    this.bullet.getChildByName('boom').active = true;
+    this.scheduleOnce(() => {
+      this.bullet.getChildByName('boom').active = false;
+    }, 0.2);
+  }
+
+  bulletSpeed = 200;
+  update(dt) {
+    if (!this.fireFlag) return;
+
+    let targetPos: cc.Vec2 = this.target.getPosition();
+    let bulletPos: cc.Vec2 = this.bullet.getPosition();
+    let normalizeVec: cc.Vec2 = targetPos.subtract(bulletPos).normalize();
+
+    this.bullet.x += normalizeVec.x * this.bulletSpeed * dt;
+    this.bullet.y += normalizeVec.y * this.bulletSpeed * dt;
+    // 角度变化以y轴正方向为起点，逆时针角度递增
+    this.bullet.angle = cc.v2(0, 1).signAngle(normalizeVec) * 180 / Math.PI;
+
+    let rect = this.target.getBoundingBox();
+    if (rect.contains(bulletPos)) this.hitTheTarget();
+  }
+}