I have a procedural approach to the game loop that runs various classes.

it looks like this:

1. continue any in progress animations
2. check for used input
3. apply AI
4. move things
5. resolve events such as collisions
6. draw it all to screen

I have seen a lot of posts about how drawing should be running separately as fast as it can, possibly in another thread.

My problem is that if the drawing runs as fast as it, can what happens if it tried to draw while I'm still applying the AI or resolving a collision? It could draw the wrong thing on screen.

This seems to be a well established idea so there must be an explanation to this problem as I just cant get my head around it. The only solution I have is to update the screen so fast that any errors like that get refreshed before we see them but that sounds hacky.

So how does this work / how would you implement it so that they are in sync but running at different speeds?