3 ms·

Game dev here. Hardly any serious game developer uses lerp like that. I prefer a quadratic friction when I write custom friction, ie: a constant force away from

Game dev here. Hardly any serious game developer uses lerp like that. I prefer a quadratic friction when I write custom friction, ie: a constant force away from velocity, and simply ensure it doesn't go past the zero point. More controllable. Box2Ds friction uses something like v = v * 1/(1+damping*delta_time), which is a good method as well. Keep in mind it's best practice to run your game logic at a constant update rate and render an interpolated state between the current and previous game logic frame, meaning that if your game logic is frame rate dependent, you can still run it smoothly on any monitor.

05 2y ago
> run your game logic at a constant update rate and render an interpolated state between the current and previous game logic frame But if graphics frame rate is higher you won’t be able to interpolate until the next logic frame is ready, - wouldn’t that increase latency?
- marcosdumay 2y ago
  It will keep latency constant, at right the amount you tested the game with.
- nightowl_games 2y ago
  Technically, 'yes', but with huge caveats. You will still show player movement at the same 'latency', just _less than a full simulation frames worth_. The benefits _far_ outweigh the costs of the other options. Games look _horrible_ if you render the physics at a different frame rate than the rest of the game. Like, horridly bad.
stephc_int13 2y ago
Constant update rate is a must, and can even be tweaked to minimize input latency if you are using a custom engine. Using two frames to interpolate at render time is adding one frame of latency. It is possible to do it on a single frame, extrapolating instead of interpolating, but you have to use a simple but uncommon trick to make it robust. The latency gain is not a full frame but some sizeable fraction of a frame, I think it is worth it for some games.
- bschwindHN 2y ago
  What is the simple but uncommon trick?
  - bavell 2y ago
    Some sort of Kalman-esque algo? https://en.wikipedia.org/wiki/Kalman_filter https://en.wikipedia.org/wiki/Kalman_filter
- nightowl_games 2y ago
  > I think it is worth it for some games. What types of games are you thinking? Extrapolation isnt worth the chance of misprediction if it's a player movement based game. The 'input latency' introduced by interpolating between frames is far different than typical 'input latency'. It's less than a single frame, and the game still renders movement at the same frame, just less movement. Most 'input latency' tests only test for _any_ movement, so those kinds of tests would detect 0 difference between 'interpolation', 'extrapolation' and 'render the exact game state'. I'm a fast paced gamer, and I make fast paced games, I've never once 'felt' the input latency from interpolating the players position between simulation frames.

05 2y ago

> run your game logic at a constant update rate and render an interpolated state between the current and previous game logic frame But if graphics frame rate is higher you won’t be able to interpolate until the next logic frame is ready, - wouldn’t that increase latency?

marcosdumay 2y ago
It will keep latency constant, at right the amount you tested the game with.
nightowl_games 2y ago
Technically, 'yes', but with huge caveats. You will still show player movement at the same 'latency', just _less than a full simulation frames worth_. The benefits _far_ outweigh the costs of the other options. Games look _horrible_ if you render the physics at a different frame rate than the rest of the game. Like, horridly bad.

stephc_int13 2y ago

Constant update rate is a must, and can even be tweaked to minimize input latency if you are using a custom engine. Using two frames to interpolate at render time is adding one frame of latency. It is possible to do it on a single frame, extrapolating instead of interpolating, but you have to use a simple but uncommon trick to make it robust. The latency gain is not a full frame but some sizeable fraction of a frame, I think it is worth it for some games.

bschwindHN 2y ago
What is the simple but uncommon trick?
- bavell 2y ago
  Some sort of Kalman-esque algo? https://en.wikipedia.org/wiki/Kalman_filter https://en.wikipedia.org/wiki/Kalman_filter
nightowl_games 2y ago
> I think it is worth it for some games. What types of games are you thinking? Extrapolation isnt worth the chance of misprediction if it's a player movement based game. The 'input latency' introduced by interpolating between frames is far different than typical 'input latency'. It's less than a single frame, and the game still renders movement at the same frame, just less movement. Most 'input latency' tests only test for _any_ movement, so those kinds of tests would detect 0 difference between 'interpolation', 'extrapolation' and 'render the exact game state'. I'm a fast paced gamer, and I make fast paced games, I've never once 'felt' the input latency from interpolating the players position between simulation frames.