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2026-04-10 22:59:39 +08:00
commit cc2e7b9bb0
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+/**
+ * Bullet.js
+ * Bullet entity that travels in a straight line and interacts with terrain/tanks.
+ */
+
+const {
+  BULLET_SPEED,
+  BULLET_SIZE,
+  DIRECTION,
+  DIR_VECTORS,
+  MAP_OFFSET_X,
+  MAP_OFFSET_Y,
+  MAP_WIDTH,
+  MAP_HEIGHT,
+} = require('../base/GameGlobal');
+
+class Bullet {
+  constructor() {
+    this.x = 0;
+    this.y = 0;
+    this.direction = DIRECTION.UP;
+    this.speed = BULLET_SPEED;
+    this.size = BULLET_SIZE;
+    this.halfSize = BULLET_SIZE / 2;
+    this.alive = false;
+    this.canBreakSteel = false;
+
+    /** @type {'player'|'enemy'} */
+    this.owner = 'player';
+    /** @type {object|null} Reference to the tank that fired this bullet */
+    this.ownerTank = null;
+  }
+
+  /**
+   * Initialize/reset the bullet for reuse from object pool.
+   * @param {object} config
+   * @param {number} config.x
+   * @param {number} config.y
+   * @param {number} config.direction
+   * @param {string} config.owner - 'player' or 'enemy'
+   * @param {boolean} [config.canBreakSteel]
+   * @param {object} [config.ownerTank]
+   */
+  init(config) {
+    this.x = config.x;
+    this.y = config.y;
+    this.direction = config.direction;
+    this.owner = config.owner || 'player';
+    this.canBreakSteel = config.canBreakSteel || false;
+    this.ownerTank = config.ownerTank || null;
+    this.alive = true;
+  }
+
+  /**
+   * Update bullet position.
+   * @param {number} dt - Delta time in seconds.
+   */
+  update(dt) {
+    if (!this.alive) return;
+
+    const vec = DIR_VECTORS[this.direction];
+    const moveAmount = this.speed * dt * 60;
+
+    this.x += vec.dx * moveAmount;
+    this.y += vec.dy * moveAmount;
+
+    // Check map boundaries
+    if (
+      this.x < MAP_OFFSET_X ||
+      this.y < MAP_OFFSET_Y ||
+      this.x > MAP_OFFSET_X + MAP_WIDTH ||
+      this.y > MAP_OFFSET_Y + MAP_HEIGHT
+    ) {
+      this.destroy();
+    }
+  }
+
+  /**
+   * Render the bullet.
+   * @param {CanvasRenderingContext2D} ctx
+   */
+  render(ctx) {
+    if (!this.alive) return;
+
+    ctx.fillStyle = this.owner === 'player' ? '#FFFF00' : '#FF6600';
+    ctx.fillRect(
+      this.x - this.halfSize,
+      this.y - this.halfSize,
+      this.size,
+      this.size
+    );
+  }
+
+  /**
+   * Get bounding box.
+   * @returns {{x: number, y: number, w: number, h: number}}
+   */
+  getBounds() {
+    return {
+      x: this.x - this.halfSize,
+      y: this.y - this.halfSize,
+      w: this.size,
+      h: this.size,
+    };
+  }
+
+  /**
+   * Destroy the bullet (mark for recycling).
+   */
+  destroy() {
+    this.alive = false;
+    // Decrement owner's active bullet count
+    if (this.ownerTank && typeof this.ownerTank.activeBullets === 'number') {
+      this.ownerTank.activeBullets = Math.max(0, this.ownerTank.activeBullets - 1);
+    }
+  }
+}
+
+module.exports = Bullet;