feat: add poc

src/systems/ProjectileSystem.js

@@ -0,0 +1,83 @@
+import { System } from '../core/System.js';
+
+export class ProjectileSystem extends System {
+  constructor() {
+    super('ProjectileSystem');
+    this.requiredComponents = ['Position', 'Velocity'];
+    this.priority = 18;
+  }
+
+  process(deltaTime, entities) {
+    const playerController = this.engine.systems.find(s => s.name === 'PlayerControllerSystem');
+    const _player = playerController ? playerController.getPlayerEntity() : null;
+
+    entities.forEach(entity => {
+      const health = entity.getComponent('Health');
+      if (!health || !health.isProjectile) return;
+
+      const position = entity.getComponent('Position');
+      if (!position) return;
+
+      // Check range - remove if traveled beyond max range
+      if (entity.startX !== undefined && entity.startY !== undefined && entity.maxRange !== undefined) {
+        const dx = position.x - entity.startX;
+        const dy = position.y - entity.startY;
+        const distanceTraveled = Math.sqrt(dx * dx + dy * dy);
+
+        if (distanceTraveled >= entity.maxRange) {
+          this.engine.removeEntity(entity);
+          return;
+        }
+      }
+
+      // Check lifetime as backup
+      if (entity.lifetime !== undefined) {
+        entity.lifetime -= deltaTime;
+        if (entity.lifetime <= 0) {
+          this.engine.removeEntity(entity);
+          return;
+        }
+      }
+
+      // Check collisions with enemies
+      const allEntities = this.engine.getEntities();
+      allEntities.forEach(target => {
+        if (target.id === entity.owner) return;
+        if (target.id === entity.id) return;
+        if (!target.hasComponent('Health')) return;
+        if (target.getComponent('Health').isProjectile) return;
+
+        const targetPos = target.getComponent('Position');
+        if (!targetPos) return;
+
+        const dx = targetPos.x - position.x;
+        const dy = targetPos.y - position.y;
+        const distance = Math.sqrt(dx * dx + dy * dy);
+
+        if (distance < 20) {
+          // Hit!
+          const targetHealth = target.getComponent('Health');
+          const damage = entity.damage || 10;
+          targetHealth.takeDamage(damage);
+
+          // If target is dead, mark it for immediate removal
+          if (targetHealth.isDead()) {
+            target.active = false;
+            // DeathSystem will handle removal
+          }
+
+          // Remove projectile
+          this.engine.removeEntity(entity);
+        }
+      });
+
+      // Boundary check
+      const canvas = this.engine.canvas;
+      if (position.x < 0 || position.x > canvas.width ||
+                position.y < 0 || position.y > canvas.height) {
+        this.engine.removeEntity(entity);
+      }
+    });
+  }
+}
+