The right way to detect collisions of many objects

[bebewr]

Hello guys, the answer to my question might be obvious to you, but i have some doubts about the right way I should detect collisions in my program.
So far, I've created three classes: Player, Projectile and Mob.
I move Player object and shoot with Projectile objects,putting them into std::vector projectilesvector. Mobs spawn randomly and they are saved in std::vector mobsvector. In every game loop I check all Projectiles object's and Mob's objects, if they intersect:

for( int i = 0; i < projectilesvector.size(); i++ )
{
        for( int j = 0; j < mobsvector.size(); j++ )
       {
        //   if ( projectilesvector[i] intersects mobsvector[j] ) collision detected
       }
}
 

For example, with 500 projectiles and 100 mobs I have to make it through 50000 loops, which takes substantial amount of time.
I wonder if there is a faster way to check collisions, without nested loops.

[Laurent]

What you need is space partitioning, for example a quad-tree.

[eXpl0it3r]

One common solution is to use a quadtree. There are many resources out there about this.

Does your game have 500 bullets at once? And did you actually notice performance issues?

[bebewr]

What you need is space partitioning, for example a quad-tree.

Thanks for feedback, this is what I needed

Does your game have 500 bullets at once? And did you actually notice performance issues?

I'm trying to write a primitive engine for future projects, so I've been testing different amounts of objects. I couldn't see the perfomance issues by my eyes, but keeping in mind, that the final program would be much bigger,  the time needed to process one frame was just too big.