Meshlet Preprocessor not working ?

[autumn crystal]

I'm using bevy skien and I am having issues with the meshlet processor.

I have and Observe that i use to convert meshes to meshlets :

fn mesh_to_meshlet(mut world: DeferredWorld, HookContext { entity, .. }: HookContext) {
    let debug_material = world
        .resource_mut::<Assets<MeshletDebugMaterial>>()
        .add(MeshletDebugMaterial::default());
    let mesh_id = world.get::<Mesh3d>(entity).unwrap().id();

    let mesh = match world.resource::<Assets<Mesh>>().get(mesh_id) {
        Some(mesh) => mesh,
        None => {
            error!("Mesh not found for mesh_id: {:?}", mesh_id);
            return;
        }
    };

    info!(
        "vertex_count: {}, primitives: {:?}, nb of indicies {}",
        mesh.count_vertices(),
        mesh.primitive_topology(),
        mesh.indices().unwrap().len()
    );

    let meshlet = match MeshletMesh::from_mesh(mesh, 22) {
        Ok(meshlet) => meshlet,
        Err(err) => {
            error!("Failed to create meshlet: {err}");
            return;
        }
    };

    let meshlet_handle = world.resource_mut::<Assets<MeshletMesh>>().add(meshlet);

    let mut commands = world.commands();
    entity! {
        <commands|entity>
        MeshletMesh3d(meshlet_handle);
        MeshMaterial3d(debug_material);
        Transform::from_xyz(0.,4.,0.);
        .remove::<Mesh3d>()
        .remove::<GltfMeshExtras>()
        .remove::<MeshletFromMesh>()
        .remove::<MeshMaterial3d<StandardMaterial>>();
    }
}

The issue is that the meshlet processor is able to make a meshlet but doesnt seem to update the clusters no matter where i move the camera.
I have other meshlets in my scene that i loaded from the bevy repo which where already preprocessed and they work fine.
Am i missing something ?

also here is the entity to wich i applied the MeshFromMeshlet Struct:

[old hull]

I'm taking a look at this meshlet saver for a potential connection https://github.com/FastestMolasses/meshlet_processing/blob/main/src/main.rs

this could also be useful #1320173864671514654 message

trying to figure out exactly what's going on such that the clusters aren't being updated...might not be here, however.

could you provide a few screenshots?

[autumn crystal]

no matter what the clusters dont change

[old hull]

What happens if you do

    entity! {
        <commands|entity>
        MeshletMesh3d(meshlet_handle);
        MeshMaterial3d(debug_material);
        Transform::from_xyz(0.,4.,0.);
        .remove::<Mesh3d>()
        .remove::<GltfMeshExtras>()
        .remove::<MeshletFromMesh>()
        .remove::<MeshMaterial3d<StandardMaterial>>()
        .remove::<GlobalTransform>()
    }

I'm not as familiar with bevy hooks as I am with observers...but it's possible that because this entity has a global transform and other components prior to inserting, that those components are interfering with the meshlet transform processing

If you're using bevy_skein, then I'm guessing that since this component is a child of a scene, that may have something to do with it...
so let me see if this works...(writing some code)

fn mesh_to_meshlet(mut world: DeferredWorld, HookContext { entity, .. }: HookContext) {
    let debug_material = world
        .resource_mut::<Assets<MeshletDebugMaterial>>()
        .add(MeshletDebugMaterial::default());
    let mesh_id = world.get::<Mesh3d>(entity).unwrap().id();

    let mesh = match world.resource::<Assets<Mesh>>().get(mesh_id) {
        Some(mesh) => mesh,
        None => {
            error!("Mesh not found for mesh_id: {:?}", mesh_id);
            return;
        }
    };

    info!(
        "vertex_count: {}, primitives: {:?}, nb of indicies {}",
        mesh.count_vertices(),
        mesh.primitive_topology(),
        mesh.indices().unwrap().len()
    );

    let meshlet = match MeshletMesh::from_mesh(mesh, 22) {
        Ok(meshlet) => meshlet,
        Err(err) => {
            error!("Failed to create meshlet: {err}");
            return;
        }
    };

    let meshlet_handle = world.resource_mut::<Assets<MeshletMesh>>().add(meshlet);

    let meshlet_handle = world.resource_mut::<Assets<MeshletMesh>>().add(meshlet);

    let mut commands = world.commands();
    commands.entity(entity).despawn();
    commands.spawn((
        MeshletMesh3d(meshlet_handle),
        MeshMaterial3d(debug_material),
        Transform::from_xyz(0., 4., 0.),
    ));
}

edit: just realized I added something extra which was getting the transform for the entity. this is probably not a great idea if the scene root is offset. could get globaltransform or just replace with your original transform

You could alternatively despawn only the entity and attach any children to the new entity

[autumn crystal]

messing with the transform seems to make it not render

[old hull]

shoot

[autumn crystal]

it just becomes invisible

it rebecomes visible when i give it avian physics tho but still broken

[old hull]

wat

[autumn crystal]

I tried :

    entity! {
        <commands|entity>
        Transform::from_xyz(0.,4.,0.);
        MeshletMesh3d(meshlet_handle);
        MeshMaterial3d(debug_material);
        .remove::<Mesh3d>()
        .remove::<ChildOf>()
        .remove::<GlobalTransform>()
        .remove::<GltfMeshExtras>()
        .remove::<MeshletFromMesh>()
        .remove::<MeshMaterial3d<StandardMaterial>>();
    }

and it made the meshlet invisible

[old hull]

wow, one sec alice's talk is on at rustconf but I'll get back

[autumn crystal]

hmmm

I applied the blender scales to the mesh and exported it.

    entity! {
        <commands|entity>
        Transform::from_xyz(0.,4.,0.);
        MeshletMesh3d(meshlet_handle);
        MeshMaterial3d(debug_material);
        .remove::<Mesh3d>()
        // .remove::<ChildOf>()
        // .remove::<GlobalTransform>()
        .remove::<GltfMeshExtras>()
        .remove::<MeshletFromMesh>()
        .remove::<MeshMaterial3d<StandardMaterial>>();
    }

this is the mesh in blender :

[old hull]

https://tenor.com/view/wtf-what-the-fuck-the-fuck-is-this-wth-gif-17571836

[autumn crystal]

all transforms are fine :

it just looks like the meshlet processor is having a stroke

i created another mesh just to make sure its not just corrupted

let me cargo clean

that did not fix the issue

[old hull]

no, this is some funk for sure

something's off. do you have a larger example? I'm quite interested

[old hull]

it's as if the mesh has been replaced by something else

like a fat cube

what happens if you give this a white mesh material?

being a child of a scene is my hunch

[autumn crystal]

i tried removing the childOf so that it apears without any parents

but it just becomes invisible

[autumn crystal]

im gonna do this again

AHHHHHH

theyre still children because of the hook

for some reason ````
commands.entity(entity).despawn();
commands.spawn((
MeshletMesh3d(meshlet_handle),
MeshMaterial3d(debug_material),
Transform::from_xyz(0., 4., 0.),
));

spawns it as a child
edit:my bad i just missread the world inspector

ill fix this later

yea still broken:

there not the child of anybody now and still behave the same

i spawned several other suzane heads with the MeshletFromMesh and they all seem to collapse at the same area

tldr the grey suzzane head does not had a MeshfromMeshlet struct

i replaced the head with a torrus

the preprocessed meshlets are fine tho :

[old hull]

Something's super suspicious. I'll look to reproduce with only the monkey head after work

[cerulean crater]

Oh this is super useful, thank you.
@loud flint you'll find this useful this if you haven't seen it yet

[loud flint]

huh interesting

should test something similar once building isn't utterly broken

[old hull]

do you have a reference issue for this btw? I'm working on this generation problem atm but would like to take a look at yours as well

[loud flint]

well i'm almost completely reworking generation to add BVH culling

so i'm not sure if the bug will still be there

[old hull]

oh amazing!

You might be interested in something I've got to show in a few...once this file's done downloading...

[loud flint]

[old hull]

Check out this tree's meshlet

kinda fire huh

[loud flint]

ouch

yeah nanite is terrible at alpha cards

[old hull]

you're dropping some important words I need to look into hahaha

[loud flint]

nanite is the UE5's virtual geometry which is what sparked basically everyone's interest in it

[old hull]

I mean alpha cards 🤔

[loud flint]

alpha cards are a technique used for foliage where each leaf is a quad and you use alpha to basically cut the shape out

[old hull]

the weird part I don't understand is...where is the trunk??

[loud flint]

a quad can't really be shrimplified so nanite just fails on it

[loud flint]

probably a cull or shrimplification fail

dunno for sure

[old hull]

interesting...

[loud flint]

i'm trying to ensure the bvh builder will panic/error if it messes up so hopefully we don't have silent failures in the future

[old hull]

Here's this demo if it's of any use https://github.com/dsgallups/meshlet-debug.git
I'll branch off main to work on this thread's original problem

[loud flint]

cheers will take a look

[autumn crystal]

thanks to @old hull it turn out i put the vertex_position_quantization_factor in the MeshletMesh::from_mesh to a value that was too high

dsgallups fixed it by changing it from 22 to 1

putting this here for people that run in the same issue

[loud flint]

there's alsoMESHLET_DEFAULT_VERTEX_POSITION_QUANTIZATION_FACTOR which is 4

[cerulean crater]

Ideally in the future there will be an automatic adaptive default, but it's not been a priority to implement