Unexpected crash from the function Dir3::new_unchecked when launching the App

[craftyneil]

Bevy version

0.15.1

[Optional] Relevant system information

cargo 1.83.0 (5ffbef321 2024-10-29)

Ubuntu 22.04.5 LTS

`AdapterInfo { name: "NVIDIA GeForce RTX 2070", vendor: 4318, device: 7938, device_type: DiscreteGpu, backend: Vulkan }`

What you did

My game hadn't crash before I add the Gun component to the player as a child component like this

pub fn spawn_gun(
    mut commands: Commands,
    player_asset: Res<PlayerAsset>,
    player: Single<(&Transform, Entity), With<Player>>,
) {
    let (player_transform, player_id) = player.into_inner();
    let gun_translation = player_transform
        .translation
        .xy()
        // extend the Vec3 coordinates with the offset
        // by adding or substracting the offset depending on the sign of the Vec3 coordinates
        //                           /*           false => -1 and true => 1            */
        .map(|el| el + (GUN_OFFSET * (el.is_sign_positive() as i32 as f32 - 0.5) * 2f32))
        .extend(0f32);
    info!("player_translation = {:#?}", player_transform.translation);
    info!("gun_translation = {:#?}", gun_translation);

    commands
        .entity(player_id)
        .with_child((
            Gun::new(player_transform.translation, gun_translation), // here
            Sprite::from_image(player_asset.gun_image.clone()),
            Transform::from_translation(gun_translation),
        ))
}

And this is the Gun Component

#[derive(Debug, Component)]
#[require(Sprite)]
pub struct Gun {
    /// Vec3 that point where the player's gun should shoot
    pub shooting_direction: Dir3,
    /// reprsent the time to wait before the gun can shoot again
    pub shooting_speed: Duration,
}

impl Gun {
    pub fn new(player_translation: Vec3, gun_translation: Vec3) -> Self {
        let shooting_direction = Dir3::new(gun_translation - player_translation);
        info!("shooting_direction = {:#?}", shooting_direction);
        Self {
            shooting_direction: shooting_direction.unwrap(),
            shooting_speed: Duration::ZERO,
        }
    }
}

What went wrong

I was expecting the Gun to spawn next to the player.

But I received this panic message

thread 'Compute Task Pool (4)' panicked at /home/craftyneil/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bevy_math-0.15.1/src/direction.rs:63:9:
Error: The vector given to `Dir3::new_unchecked` is not normalized. The length is NaN.
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Encountered a panic in system `bevy_render::view::visibility::update_frusta<bevy_render::camera::projection::OrthographicProjection>`!
Encountered a panic in system `bevy_app::main_schedule::Main::run_main`!
zsh: segmentation fault (core dumped)  cargo run

We can see on this error message that there append to be a problem updating the position of a camera, and the only camera that I spawned was the player camera like that

pub fn spawn_player(mut commands: Commands, player_asset: Res<PlayerAsset>) {
    commands.spawn((
        Player,
        Sprite::from_image(player_asset.player_image.clone()),
        //                    normalise a Vec3 with z=0
        Transform::from_scale(Vec2::ONE.extend(0f32).normalize() * PLAYER_SCALE_FACTOR),
    ));
}

Since the problem was related to a Dir3, I verified the Gun::new() function, since it's the only place where I use a Dir3. But the function here

pub fn new(player_translation: Vec3, gun_translation: Vec3) -> Self {
        let shooting_direction = Dir3::new(gun_translation - player_translation);
        // ...
        Self {
            shooting_direction: shooting_direction.unwrap(), //here
            // ...
        }
    }

unwraped a Ok variant with this value

shooting_direction = Ok(
    Dir3(
        Vec3(
            0.70710677,
            0.70710677,
            0.0,
        ),
    ),
)

Then, someone suggested to me in the bevy server that a maybe messed with the camera transform, witch I don't because the program crashed because I couldn't even move the player, and so, the gun, so the problem is not with the camera's Transform modification in the other functions but when I spawn the camera. I even tried to move the place where I spawn the camera from the function spawn_player to the function spawn_gun like this

pub fn spawn_gun(
    mut commands: Commands,
    player_asset: Res<PlayerAsset>,
    player: Single<(&Transform, Entity), With<Player>>,
) {
    // ...

    commands.entity(player_id).with_child((
        Gun::new(player_transform.translation, gun_translation),
        Sprite::from_image(player_asset.gun_image.clone()),
        Transform::from_translation(gun_translation),
        Camera2D  // <---------------------------------------------------------  here 
    ));
}

but it still crashed.
The only way to make it not crash was to not spawn the Camera2D.

Additional information

the full log with RUST_BACKTRACE=1;

    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.67s
     Running `target/debug/unexpected_mutation`
2025-01-06T18:03:53.209271Z  INFO bevy_diagnostic::system_information_diagnostics_plugin::internal: SystemInfo { os: "Linux 22.04 Ubuntu", kernel: "6.8.0-49-generic", cpu: "AMD Ryzen 5 3600 6-Core Processor", core_count: "6", memory: "15.5 GiB" }
2025-01-06T18:03:53.331919Z  INFO bevy_render::renderer: AdapterInfo { name: "NVIDIA GeForce GT 1030", vendor: 4318, device: 7425, device_type: DiscreteGpu, driver: "NVIDIA", driver_info: "535.183.01", backend: Vulkan }
2025-01-06T18:03:54.138732Z  INFO bevy_winit::system: Creating new window "Unexpected Mutation" (0v1#4294967296)
2025-01-06T18:03:54.138833Z  INFO winit::platform_impl::linux::x11::window: Guessed window scale factor: 1
2025-01-06T18:03:54.550251Z  INFO bevy_asset_loader::loading_state::systems: Loading state 'unexpected_mutation::AppLoadingStates::AssetLoading' is done
2025-01-06T18:03:54.616406Z  INFO unexpected_mutation::player::system: player_translation = Vec3(
    0.0,
    0.0,
    0.0,
)
2025-01-06T18:03:54.616441Z  INFO unexpected_mutation::player::system: gun_translation = Vec3(
    2.0,
    2.0,
    0.0,
)
2025-01-06T18:03:54.616457Z  INFO unexpected_mutation::player::gun::component: shooting_direction = Ok(
    Dir3(
        Vec3(
            0.70710677,
            0.70710677,
            0.0,
        ),
    ),
)
thread '<unnamed>' panicked at /home/craftyneil/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bevy_math-0.15.1/src/direction.rs:63:9:
Error: The vector given to `Dir3::new_unchecked` is not normalized. The length is NaN.
stack backtrace:

   0: rust_begin_unwind
             at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/std/src/panicking.rs:665:5
   1: core::panicking::panic_fmt
             at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/core/src/panicking.rs:74:14
   2: bevy_math::direction::assert_is_normalized
             at /home/craftyneil/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bevy_math-0.15.1/src/direction.rs:63:9
   3: bevy_math::direction::Dir3::new_unchecked
             at /home/craftyneil/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bevy_math-0.15.1/src/direction.rs:402:9
   4: bevy_transform::components::global_transform::GlobalTransform::back
             at /home/craftyneil/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bevy_transform-0.15.1/src/components/global_transform.rs:61:13
   5: bevy_render::camera::projection::CameraProjection::compute_frustum
             at /home/craftyneil/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bevy_render-0.15.1/src/camera/projection.rs:92:14
   6: bevy_render::view::visibility::update_frusta
             at /home/craftyneil/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bevy_render-0.15.1/src/view/visibility/mod.rs:388:20
   7: core::ops::function::FnMut::call_mut
             at /home/craftyneil/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:166:5
   8: core::ops::function::impls::<impl core::ops::function::FnMut<A> for &mut F>::call_mut
             at /home/craftyneil/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:294:13
   9: <Func as bevy_ecs::system::function_system::SystemParamFunction<fn(F0) .> Out>>::run::call_inner
             at /home/craftyneil/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bevy_ecs-0.15.1/src/system/function_system.rs:1002:21
  10: <Func as bevy_ecs::system::function_system::SystemParamFunction<fn(F0) .> Out>>::run
             at /home/craftyneil/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bevy_ecs-0.15.1/src/system/function_system.rs:1005:17
  11: <bevy_ecs::system::function_system::FunctionSystem<Marker,F> as bevy_ecs::system::system::System>::run_unsafe
             at /home/craftyneil/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bevy_ecs-0.15.1/src/system/function_system.rs:800:19
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
Encountered a panic in system `bevy_render::view::visibility::update_frusta<bevy_render::camera::projection::OrthographicProjection>`!
Encountered a panic in system `bevy_app::main_schedule::Main::run_main`!

[hymm]

The z scale on the player transform being zero might be the problem. What are you trying to do there with the scale?

[craftyneil]

The scale is to help me resize the player in an easy way but I found thanks to you that the problem was that the z scale was set at 0, thanks.