I may misunderstood this: but you want a 1 cm square to appear 1 cm on every screen, first of all you need to get physical screen size let it be vec2 scr_size;

Hiwever you don't want to multiply by aspect ratio, which anyway is not the case cause you already multiple by projection matrix..

Now positi…

I can't recommend Christer Ericson's book Real-Time Collision Detection enough, it basically has all the answers and comes with code samples. It really is a must have.

You need to take into account that >>you<< have to pay for such a game for every player you'll have in the end because the game running on a server will cause third-party services like AWS to run on a higher workload and the service provider wants this costs back from you. So the main q…

Ok, thaks for all your replies, they help a lot.