Godot - Speed up the game without breaking physics

Question

I'm making a soccer simulation game and for that I'm using normal 2DBody nodes for the players and ball. But I would like to be able to speed up the game, without breaking the physics and getting other results.

To speed up the game I found Engine.time_scale and Engine.iterations_per_second that affect the game speed.

So default values for timescale = 1 and for iterations_per_second = 60

By just setting time_scale = 0.5, physics seem to break. At least I can see, that it looks less natural than on normal speed.

When fasting up by setting time_scale = 0.5 and iterations per second = 120, so physics don't seem to break. But I can't really tell if this is 100% true. (Also 99% would be okay ;-) )

So does somebody know another way to speed up the game without breaking physics or can confirm, that modified time_scale and iterations per second don't break physics?

Answer 1

First of all, Godot documentation says:

float time_scale - Controls how fast or slow the in-game clock ticks versus the real life one. It defaults to 1.0. A value of 2.0 means the game moves twice as fast as real life, whilst a value of 0.5 means the game moves at half the regular speed.

So if you want to speed up the game time you should increase that value, not decrease. As far as I understand this value will influence how much time delta is passed to _physics_process(delta) methods (and other engines internal physics calculations), and time_scale works as a multiplayer for that value.

Physics engine runs with a fixed time step, so iterations_per_second will influence it as documentation mentions:

int iterations_per_second - The number of fixed iterations per second (for fixed process and physics).

Yes, modifying both values should give better results, because increasing iterations_per_second makes calculations of physics more frequent and that means more precise (let's call it "time detailing"). Could it still "break physics"? Yes, if physics calculations won't be fast enough to keep up with engine iteration frequency. In that case the only solution will be to optimize your game.