Adding a PointLight crashes the app

[IceSentry]

When I try to use this plugin with a scene with a point light it crashes.

For example, if I add a point light in the 3d example of this repo I get this error:

2022-02-20T18:57:30.397787Z ERROR wgpu::backend::direct: Handling wgpu errors as fatal by default
thread 'main' panicked at 'wgpu error: Validation Error

Caused by:
    In a RenderPass
      note: encoder = `<CommandBuffer-(0, 2, Vulkan)>`
    In a draw command, indexed:false indirect:false
      note: render pipeline = `shadow_pipeline`
    vertex 6 extends beyond limit 5 imposed by the buffer in slot 0. Did you bind the correct `Vertex` step-rate vertex buffer?

I don't get this error if I don't spawn a point light.

I tried it with bevy 0.6 and the latest bevy main and the bevy-main branch of this repo. This is on windows 10.

[IceSentry]

I also tried it with the DX12 backend and I get the same error

[Toqozz]

Can you see if this is still happening with 0.6.0?

I made a fair few changes before getting to this and I never reproduced.

Here's how I'm adding a point light in the 3d example to try to reproduce:

fn setup(mut commands: Commands, mut lines: ResMut<DebugLines>) {
    commands.spawn_bundle(PerspectiveCameraBundle {
        transform: Transform::from_translation(Vec3::new(0.0, 0.0, 5.0)),
        ..Default::default()
    });
    commands.spawn_bundle(PointLightBundle {
       ..Default::default() 
    });
    // A line that stays on screen 9 seconds
    lines.line_gradient(
        Vec3::new(1.0, -1.0, -1.0),
        Vec3::new(-1.0, 1.0, 1.0),
        9.0,
        Color::CYAN,
        Color::MIDNIGHT_BLUE,
    );
}

[IceSentry]

So, I just tried it with 0.6.0 and I still get the same crash, but I noticed it only crashes when shadows are enabled on the point light. If shadows are not enabled it doesn't crash.

Here's how I was spawning it.

    commands.spawn_bundle(PointLightBundle {
        point_light: PointLight {
            intensity: 1500.0,
            shadows_enabled: true, // This seems to be the issue
            ..Default::default()
        },
        transform: Transform::from_xyz(4.0, 8.0, 4.0),
        ..Default::default()
    });

[Toqozz]

So I've just disabled shadows (we shouldn't be casting/receiving shadows anyway) in 0.6.1, which seems to fix this, but still will have a look into what causes it.

[IceSentry]

I just tried 0.6.1 with shadows on the point light and I can confirm it works.

[Toqozz]

I think this is related to bevyengine/bevy#3959, where meshes with custom attributes seem to potentially get screwed up if they don't have an index buffer (and even then sometimes). If I add mesh indices then it doesn't crash with shadows enabled.

I won't close this for now since it might be the cause of other random issues if they come up.

Relevant thread from Discord:

[1:52 AM] thebracket: Adding an index buffer fixed the crash. I guess non-indexed buffers aren't a good idea now.
[2:00 AM] François 🥷🏻: I think they should be? bevyengine/bevy#3415
is the Bevy version you're using with this PR?
[2:00 AM] thebracket: Looks like the PR is pulling head from main, so it should be in there.
[2:03 AM] thebracket: I'll try and make a self-contained example, it's tied into a lot of other code. That'll probably help find the issue (with an index buffer, it's faster anyway - but it seems like that should have worked)
[2:04 AM] Gibonus 🙈: Yeah, as the author of the PR, I can't say I didn't overlook anything
[2:28 AM] thebracket: Interestingly, when I copied over the code into a self-contained example it worked. So I must have something wrong hidden in there that didn't crash the previous version.
[2:31 AM] thebracket: Got it. It crashes when I add a tangent buffer to a non-indexed mesh.
[2:32 AM] thebracket: https://gist.github.com/thebracket/4d5507a7fb3380a911b8912f219c1a67
[2:32 AM] François 🥷🏻: ha! then you would probably need bevyengine/bevy#3120 which allows you to use the attributes you want in the order you want instead of exactly what Bevy shader expect
[2:36 AM] thebracket: That looks like a great PR in general, custom buffer entries are pretty painful.
[2:39 AM] thebracket: Adding an index buffer is interesting. It doesn't crash. Without tangents, you get the expected output:
[2:40 AM] thebracket: With tangents, it doesn't crash - but the data is all over the place.
[2:40 AM] thebracket: (Same index buffer for both)
[2:41 AM] François 🥷🏻: yep, that's the issue, it's using the wrong attribute value as it's not in the order expected
[2:44 AM] thebracket: Yikes, ok. I guess I'll chug along without tangents (and presumably no per-pixel shading, since you typically need tangents for normal map calculation in a pbr pipeline). Thanks!
[3:17 AM] thebracket: With tangents disabled, Pyrite Box works with 0.6.
[3:20 AM] François 🥷🏻: nice!