如何删除OpenGL绘制的C ++对象？

Question

I have a list(vector) of objects, which are continuously being drawn on screen. During the glutMainLoop, I have this glutTimerFunction update, which periodically checks if an object goes out of the screen boundaries, and if it is so, it deletes the object. This is giving a segmentation fault.

Here is the class ->

class bullet
{
   private:
   public:
     void update();
     bool check()
     {
        if(y>=box_len/2)
        {
        return true;
        }
        return false;
     }
     void draw();
};
vector <bullet*> bullets;

Here is the update function ->

void update(int value)
{
  for( typeof(bullets.begin()) it= bullets.begin(); it!= bullets.end();it++)
  {
    if((*it)!=NULL)
    {
      if(*it)->check())
      {
        delete *it;
        bullets.erase(it);
      }
    }
  }
  glutTimerFunc(10, update, 0);
}

Registerd with glut in main() as

glutTimerFunc(10, update, 0);

Answer 1

I'm guessing tr is some sort of foreach macro?

In which case, removing an item from your vector will invalidate the iterator.

Use it = bullets.erase(it); to ensure your iterator stays valid.

Answer 2

When the element being deleted is the last element, the iterator becomes the next element ( bullets.end() in this case). The increment at the end of the for loop, causes it to become something invalid and was the reason for the segfault.

Repaired code ->

void update(int value)
{
  for( typeof(bullets.begin()) it= bullets.begin(); it!= bullets.end();it++)
  {
   if((*it)!=NULL)
   {
     if(*it)->check())
     {
      delete *it;
      bullets.erase(it);
      if(it==bullets.end())
        break;
     }
   }
  }
  glutTimerFunc(10, update, 0);
}