Time

[UglyBob]

Why can I not adjust the time on the sim? I set it for 1 day per second or 1 year per second, or whatever and then it just resets itself to something completely different. Its very irritating. Help please.

[Physics_Hacker]

That has to do with your framerate, which can't show exactly what you asked for, so it goes for the "next best thing"

[The Ventifact]

That has to do with your framerate, which can't show exactly what you asked for, so it goes for the "next best thing"

I thought it had more to do with how planets and moons are kept in orbit. That was one of the things GA wanted to fix was planets being flung out of orbit at high time steps. US1 had that problem during fast timesteps. In Universe Sandbox 2, its mostly fixed. I remember back in Alpha 8 or 9 you could go up to extremely insane timesteps and the orbits still kept their cool. With the last few updates, you can no longer do that with simulations that have a lot of bodies and objects, it throttles it for some reason.

And because of that, you can't run sims at high timesteps. Ones that have less objects can go REALLY high, but others with dozens/hundreds of objects, it can't. I think it has to do with keeping performance and accuracy of the simulation more then being tied to frame rate. Just imagine trying to calculate dozens of bodies and hundreds of particles at one year per second. That's fast, which may explain why it slows down. Our PC's may not be fast enough to compute speeds that quick, especially for something complex like US2.

I've got a GTX 980 paired with an i7-3770 and get fps into the hundreds (averages 100fps on most sims that are not outragous), and it slows down for me too. I can't get the "Our Solar System" simulation to any faster than 10 years per second before it throttles the timestep.

When the clock icon turns red, it means the simulation is becoming less accurate. The faster you go, less accurate it becomes. The slower, the more accurate. So I assume the game is taking accuracy over speed. I could be wrong though, this is just what I've observed.

A dev will know more about then I do, for obvious reasons of course.

[Physics_Hacker]

That has to do with your framerate, which can't show exactly what you asked for, so it goes for the "next best thing"

I thought it had more to do with how planets and moons are kept in orbit. That was one of the things GA wanted to fix was planets being flung out of orbit at high time steps. US1 had that problem during fast timesteps. In Universe Sandbox 2, its mostly fixed. I remember back in Alpha 8 or 9 you could go up to extremely insane timesteps and the orbits still kept their cool. With the last few updates, you can no longer do that with simulations that have a lot of bodies and objects, it throttles it for some reason.

And because of that, you can't run sims at high timesteps. Ones that have less objects can go REALLY high, but others with dozens/hundreds of objects, it can't. I think it has to do with keeping performance and accuracy of the simulation more then being tied to frame rate. Just imagine trying to calculate dozens of bodies and hundreds of particles at one year per second. That's fast, which may explain why it slows down. Our PC's may not be fast enough to compute speeds that quick, especially for something complex like US2.

I've got a GTX 980 paired with an i7-3770 and get fps into the hundreds (averages 100fps on most sims that are not outragous), and it slows down for me too. I can't get the "Our Solar System" simulation to any faster than 10 years per second before it throttles the timestep.

When the clock icon turns red, it means the simulation is becoming less accurate. The faster you go, less accurate it becomes. The slower, the more accurate. So I assume the game is taking accuracy over speed. I could be wrong though, this is just what I've observed.

A dev will know more about then I do, for obvious reasons of course.

That's basically what I meant, except in fewer words. As in, the framerate is affected by the accuracy of the simulation, so putting a very certain timestep isn't really possible, since the combination of the framerate and accuracy of the sim will cause it to be different than what you "asked" for. Like if I set it to real time, (1 sec/ sec) then it'll automatically set it to like 0.972 sec/sec to mainatin the accuracy that an empty sim would have, running at 1 sec/ sec.

[Greenleaf]

That has to do with your framerate, which can't show exactly what you asked for, so it goes for the "next best thing"

I will actually just paste in a previous answer about the same thing here
The question was similar to the one you just asked now, but if it is still unclear, feel free to ask again.


US² is a physics simulator. That means that it performs calculations to go from one frame to the next. It has to look at how every object moves and then figure out where it will be after some elapsed time.


You may ask it to move forward one whole year every time a frame is drawn, but depending on the simulation, this may not be something it can do in a single calculation. Perhaps it can only move forward in smaller steps of one month, while maintaining accuracy. It then has to make 12 such calculation heavy steps to go the whole year. The question is then how many calculations your computer can make in a certain amount of time. A fast computer can obviously make more than a slow one.


The end result is that you cannot go as fast as you want. There is an upper speed which your computer can handle. That is why, in the simulation you mention, your system can handle 5 years every time a second elapses in the real world - essentially a bit more than 31.5 million times faster than real time.


The value you see increasing is the speed you ask the the simulation to run at and the one, which is eventually not increasing, is the actual speed you can get. How heavy the calculations are, that depends on the number of bodies as well as on collisions.