ATP production and consumption get out of sync when the game lags

[84634E1A607A]

ATP falls sharply when I maximize the Thrive window. This problem can be reproduced in earlier releases as well. Also when I experience a game lag the ATP will suddenly fall lower than it should be.

[hhyyrylainen]

I was sure that there was already an issue for this, but I couldn't find this. I've known about this for a while.

If the game experiences a lag spike (or the framerate is too low): the ATP production slows down because the compound storage is not increased, meaning that when more ATP is produced during a longer frame simulation ATP can't be produced at the rate it should be. And then on top of that the ATP usage is correctly computed for a longer frame, so unless you have really large storage capacity you'll run out of ATP on that frame because ATP could not be produced the right amount.

I think maybe this will explain things better:

• The game experiences a lag spike, the simulation time between frames is 300ms
• ATP generation tries to run as usual, but is multiplied by the elapsed time, which is usually fine, but now multiplied by 300 the resulting compound amount doesn't fit in the cell, so the cell doesn't get that compound amount
• Now ATP usage runs, and is also multiplied by 300 to take the passed time into account
• The consumption is correctly adjusted to be really huge, but as the cell doesn't have enough storage for that amount of ATP, the cell briefly takes ATP damage as the consumption depletes the ATP of the cell

[84634E1A607A]

What if we handle the usage first? Then we will have more space to fit in.

[hhyyrylainen]

The effect would be the same: you take damage and / or can't move at normal speed as you don't have ATP to power movement.

A slightly better way would be to have the consumption be computed first, processes were ran then, and finally ATP damage would be given (if cell doesn't have any ATP), though this is hard to fit in the current design because the process system is ran on background threads (in order to speed up processing many cells on multicore CPUs). So it's not possible to fit the Microbe class doing some stuff, then processes run, and then doing stuff again.

[hhyyrylainen]

One way to limit the consumption per frame, would be to assume that the game runs at least at 15 FPS or so, and cap the maximum elapsed time for the process system and Microbe computations.

[hhyyrylainen]

With the ECS change I've now limited the game delta to 0.1 I think to make sure there cannot be massive update timesteps. So this may be fixed.