> running the physics engine at a deterministic timestep
replyAs well as using special library versions of floating-point functions which don't behave the same across different processors I suppose, if you want to be safe.
Eg cr-libm[1] or more modern alternatives like core-math[2].
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replyTying physics to framerate at all is a mistake. Like, should be filed as a bug mistake.
replyThere's no scenario in which that's desirable.
And yet even Rockstar gets it wrong. (GTA V has several framerate dependent bugs)
It's desirable for arcade games, which have fixed hardware including the display. There's no possibility of upgrading for better framerate, and the game can be designed so slowdown is rare or non-existent. Tying the physics to the framerate gives you very low and very consistent input latency with minimum developer effort.
replyRight, all valid points, but consider the scale of a game like those coming out of rockstar. I'd understand for indie games and arcade games, but a single player rpg that will likely never be seen in arcade settings? Seems odd to me to see it here. Rockstar has the resources to do it properly, one would think, no?
replyI completely agree, but it's an easy mistake to make.
replynot framerate of rendering but physics running at (its own) fixed frame rate.
replyEvery game logic update, not only physics, should run on a timer that's fully independent from the frame rate.
replyThe only place where that doesn't matter is fixed hardware - i.e. old generation consoles, before they started to make "pro" upgrades.
> i.e. old generation consoles, before they started to make "pro" upgrades.
replyAnd before it was realistically possible to port a game to run on multiple consoles without a complete rewrite.
I think you mean timestep. The video frames get updated on one timestep (the so-called "frame rate" because it is the rate at which video frames get redrawn, the inverse of its timestep), physics gets updated on a separate timestep, and gameplay or input or network polling can be updated on its own timestep.
replypretty much, over the dozen or so game and rendering engines I made over the decades name mutated from tick to timestep to frame (rate) to refresh rate (hz) to tick again.. it doesn't matter as long as every system is decoupled and rendering is unbounded (if hardware/display combo supports it). This needs thinking from day one. Cool stuff you can do then is determinism, you can do independent timers which go forward, halt, backward in time, different speed multipliers over those (so some things run slower, faster, everything goes slower / faster), etc.
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