Rendered geometry "breaks" when adding many primitives

[coljnr9]

Bevy version

main after #16985 (72ddac140a985bbfd66f8869110f3ac5e1c22b5c is the commit when bisecting main and v0.15.2)

[Optional] Relevant system information

Ubuntu Linux 22.04
dynamic_linking feature
rustc 1.86.0-nightly (a730edcd6 2025-01-30)

Adapter info

`AdapterInfo { name: "NVIDIA GeForce RTX 4080", vendor: 4318, device: 9988, device_type: DiscreteGpu, driver: "NVIDIA", driver_info: "535.183.01", backend: Vulkan }`

What you did

I'm just toying around with a tower-defense-style game. When adding the tower-placement systems, I was placing lots of Cylinders on a plane.

What went wrong

Expected:
I expected to see lots and lots of cylinders, maybe seeing the FPS drop as the number gets very large

Actual:
After a few 10s or 100s of cylinders, the geometry "turns inside out" (see videos)

Additional information

• I'm very new to Bevy, I could be using some bad memory-access pattern, and only getting lucky with ordering/optimization on older commits.
• No errors or warning in logs
• Maybe something to do with memory getting stomped?
• Occurs in both release and debug build profiles

Videos

Bad

bad.mp4

Good

good.mp4

[rparrett]

I was able to reproduce this with some code based on the 3d_viewport_to_world example. Notably, to reproduce this behavior, I was spawning each cylinder with a separate material. This likely isn't what you want to be doing, but this still seems like either a bug or something that should raise a warning at least.

SystemInfo { os: "macOS 15.3 Sequoia", kernel: "24.3.0", cpu: "Apple M4 Max", core_count: "16", memory: "64.0 GiB" }
AdapterInfo { name: "Apple M4 Max", vendor: 0, device: 0, device_type: IntegratedGpu, driver: "", driver_info: "", backend: Metal }

Expand code

use bevy::prelude::*;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_systems(Startup, setup)
        .add_systems(Update, draw_cursor)
        .init_resource::<CylinderHandles>()
        .run();
}

#[derive(Resource)]
struct CylinderHandles {
    material: Handle<StandardMaterial>,
    mesh: Handle<Mesh>,
}

impl FromWorld for CylinderHandles {
    fn from_world(world: &mut World) -> Self {
        Self {
            mesh: world.add_asset::<Mesh>(Cylinder::default()),
            material: world.add_asset::<StandardMaterial>(StandardMaterial::from_color(
                Color::hsl(120.0, 0.8, 0.7),
            )),
        }
    }
}

fn draw_cursor(
    mut commands: Commands,
    camera_query: Single<(&Camera, &GlobalTransform)>,
    ground: Single<&GlobalTransform, With<Ground>>,
    windows: Query<&Window>,
    handles: Res<CylinderHandles>,
    mouse: Res<ButtonInput<MouseButton>>,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    if !mouse.pressed(MouseButton::Left) {
        return;
    }

    let Ok(windows) = windows.get_single() else {
        return;
    };

    let (camera, camera_transform) = *camera_query;

    let Some(cursor_position) = windows.cursor_position() else {
        return;
    };

    // Calculate a ray pointing from the camera into the world based on the cursor's position.
    let Ok(ray) = camera.viewport_to_world(camera_transform, cursor_position) else {
        return;
    };

    // Calculate if and where the ray is hitting the ground plane.
    let Some(distance) =
        ray.intersect_plane(ground.translation(), InfinitePlane3d::new(ground.up()))
    else {
        return;
    };
    let point = ray.get_point(distance);

    commands.spawn((
        // Use these instead to not crash
        // Mesh3d(handles.mesh.clone()),
        // MeshMaterial3d(handles.material.clone()),
        Mesh3d(meshes.add(Cylinder::default())),
        MeshMaterial3d(materials.add(StandardMaterial::from_color(Color::hsl(120.0, 0.8, 0.7)))),
        Transform::from_translation(point + ground.up() * 0.5)
            .with_rotation(Quat::from_rotation_arc(Vec3::Z, ground.forward().as_vec3())),
    ));
}

#[derive(Component)]
struct Ground;

fn setup(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    // plane
    commands.spawn((
        Mesh3d(meshes.add(Plane3d::default().mesh().size(20., 20.))),
        MeshMaterial3d(materials.add(Color::srgb(0.3, 0.5, 0.3))),
        Ground,
    ));

    // light
    commands.spawn((
        PointLight {
            shadows_enabled: true,
            ..default()
        },
        Transform::from_xyz(4.0, 8.0, 4.0),
    ));

    // camera
    commands.spawn((
        Camera3d::default(),
        Transform::from_xyz(15.0, 5.0, 15.0).looking_at(Vec3::ZERO, Vec3::Y),
    ));

    // red cube
    commands.spawn((
        Mesh3d(meshes.add(Cuboid::default())),
        MeshMaterial3d(materials.add(Color::hsl(0.0, 0.8, 0.7))),
        Transform::from_xyz(0.0, 1.0, 0.0).with_scale(Vec3::splat(2.0)),
    ));
}

[rparrett]

cc @pcwalton is this an expected limit on the number of materials in a scene since #16985 or a different kind of bug?

[torsteingrindvik]

I also saw this yesterday, similar story: Lots of meshes using separate materials. Haven't tried via sharing materials yet.
Happened for me somewhere between spawning ~50-100 objects. Was always reproducible.

Laptop 4080, archlinux, latest main.