subtract out of bounds

[TobiasEnholmX]

[2023-07-18T15:31:26Z INFO  ambient_wasm::shared] Running startup event for module: fpsmovement_client
[2023-07-18T15:31:26Z INFO  ambient_wasm::shared] Loading module: console_client
[2023-07-18T15:31:26Z INFO  ambient_wasm::shared] Done loading module: fpsaudio_client
[2023-07-18T15:31:26Z INFO  ambient_wasm::shared] Done loading module: fpsmodel_client
[2023-07-18T15:31:26Z INFO  ambient_wasm::shared] Running startup event for module: fpsaudio_client
[2023-07-18T15:31:26Z INFO  ambient_wasm::shared] Running startup event for module: fpsmodel_client
[2023-07-18T15:31:26Z INFO  ambient_wasm::shared] Done loading module: fpsui_client
[2023-07-18T15:31:26Z INFO  ambient_wasm::shared] Running startup event for module: fpsui_client
[2023-07-18T15:31:26Z INFO  ambient_wasm::shared] Done loading module: console_client
[2023-07-18T15:31:26Z INFO  ambient::client::wasm] [fpsmodel_client] stdout: ___model loaded___
[2023-07-18T15:31:26Z INFO  ambient::client::wasm] [fpsmodel_client] stdout: ___model loaded___
[2023-07-18T15:31:26Z INFO  ambient::client::wasm] [fpsmodel_client] stdout: ___model loaded___
[2023-07-18T15:31:26Z INFO  ambient::client::wasm] [fpsmodel_client] stdout: ___model loaded___
[2023-07-18T15:31:26Z INFO  ambient::client::wasm] [fpsmodel_client] stdout: ___model loaded___
[2023-07-18T15:31:26Z INFO  ambient_wasm::shared] Running startup event for module: console_client
[2023-07-18T15:31:28Z INFO  ambient::client::wasm] [fpsmodel_client] stdout: ___model loaded___
[2023-07-18T15:32:27Z INFO  ambient::client::wasm] [fpsmodel_client] stdout: ___model loaded___
thread 'main' panicked at 'overflow when subtracting durations', library/core/src/time.rs:936:31
stack backtrace:
   0: rust_begin_unwind
             at /rustc/90c541806f23a127002de5b4038be731ba1458ca/library/std/src/panicking.rs:578:5
   1: core::panicking::panic_fmt
             at /rustc/90c541806f23a127002de5b4038be731ba1458ca/library/core/src/panicking.rs:67:14
   2: core::panicking::panic_display
             at /rustc/90c541806f23a127002de5b4038be731ba1458ca/library/core/src/panicking.rs:150:5
   3: core::panicking::panic_str
             at /rustc/90c541806f23a127002de5b4038be731ba1458ca/library/core/src/panicking.rs:134:5
   4: core::option::expect_failed
             at /rustc/90c541806f23a127002de5b4038be731ba1458ca/library/core/src/option.rs:2025:5
   5: core::option::Option<T>::expect
             at /rustc/90c541806f23a127002de5b4038be731ba1458ca/library/core/src/option.rs:913:21
   6: <core::time::Duration as core::ops::arith::Sub>::sub
             at /rustc/90c541806f23a127002de5b4038be731ba1458ca/library/core/src/time.rs:936:31
   7: ambient_animation::player::sample_animation_node
   8: ambient_ecs::query::TypedReadQuery<R>::to_system_with_name::{{closure}}
   9: <ambient_ecs::query::SystemGroup<E> as ambient_ecs::query::System<E>>::run
  10: <ambient_ecs::query::SystemGroup<E> as ambient_ecs::query::System<E>>::run
  11: <ambient_ecs::query::SystemGroup<E> as ambient_ecs::query::System<E>>::run
  12: ambient_network::client_game_state::ClientGameState::on_frame
  13: <ambient_network::native::client::ClientView as ambient_element::ElementComponent>::render::{{closure}}
  14: ambient_element::tree::ElementTree::update
  15: ambient_ecs::query::TypedReadQuery<R>::to_system_with_name::{{closure}}
  16: <ambient_ecs::query::SystemGroup<E> as ambient_ecs::query::System<E>>::run
  17: <ambient_ecs::query::SystemGroup<E> as ambient_ecs::query::System<E>>::run
  18: <ambient_ecs::query::SystemGroup<E> as ambient_ecs::query::System<E>>::run
  19: ambient_app::App::handle_static_event
  20: ambient_app::App::run_blocking::{{closure}}
  21: <winit::platform_impl::platform::app_state::EventLoopHandler<T> as winit::platform_impl::platform::app_state::EventHandler>::handle_nonuser_event
  22: winit::platform_impl::platform::app_state::Handler::handle_nonuser_event
  23: winit::platform_impl::platform::app_state::AppState::cleared
  24: std::panicking::try
  25: winit::platform_impl::platform::observer::control_flow_end_handler
  26: <unknown>
  27: <unknown>
  28: <unknown>
  29: <unknown>
  30: <unknown>
  31: <unknown>
  32: <unknown>
  33: <unknown>
  34: <unknown>
  35: <unknown>
  36: winit::platform_impl::platform::event_loop::EventLoop<T>::run
  37: ambient_app::App::run_blocking
  38: ambient::main::{{closure}}
  39: tokio::runtime::park::CachedParkThread::block_on
  40: tokio::runtime::scheduler::multi_thread::MultiThread::block_on
  41: ambient::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
[2023-07-18T15:33:09Z INFO  ambient::client] Disconnecting client
tobiasenholm@Tobiass-MacBook-Pro afps % 

[pierd]

I believe that the source of this is different clocks on server and client.

When PlayClipFromUrlNode is used on the server, it will use server's clock for start_time component, which is then sent over to the client. Then on the client a slightly different clock can be used to actually play the animation meaning that time can be before start_time causing this overflow. If time is after start_time then it won't crash but still cause a glitch.

[philpax]

@pierd What do you think are the odds of getting synchronised clocks in? I'm not confident, so I'm thinking we should just hack around this by using a saturating subtract so that it doesn't panic.

[pierd]

@philpax clock sync is not that complex (but not trivial to get right) but the list is just getting longer so I wouldn't bet on it. I agree - we should make it not crash first even if we get potential glitches (in theory we got them already anyway).

[pierd]

There's really no downside to saturating sub in this case.