How to spawn meshes in lua

[aurreland]

So i'm trying to spawn levels using lua script, but i can't seem to find a way to spawn meshes (i'm trying to spawn simple shapes like Sphere for an aim trainer), so im also wondering how to add a material.
How i am supposed to spawn them, should i use some function in world: or should i make an APIProvider ?
Could you please give me an example of how this should work.
I tried getting Assets<Mesh> ressource, putting a Sphere in a Mesh3d component, and i also tried making an APIProvider but i didn't managed to expose a function to lua.

[makspll]

BMS does not have native functionality for interacting with assets so you'd have to write your own bindings for this, what exactly was the issue in creating those?

[aurreland]

The new version make things much more simple to apprehend and everything, so far it's a lot easier to work with.
I have some questions about adding bindings,

• For example i spawn a entity with world.spawn() like local entity = world.spawn() how can i get the entity in my function like it would be add_mesh3d(entity,"mesh_type","size") because Entity doesn't implement ScriptArgument.
• Or maybe i could add a function to entity type and use self this time.
• And can i do something like commands because when i call world.commands() i can't because this make the closure a FnMut.

So what is the way to go and how would this work ?

[makspll]

because Entity doesn't implement ScriptArgument.

Entity does not itself implement ScriptArgument but you can use Val<Entity> to use it in functions, for example this is how get_parent is defined in the core functions:

        .register("get_parent", |ctxt: FunctionCallContext, e: Val<Entity>| {
            profiling::function_scope!("get_parent");
            let world = ctxt.world()?;
            let parent = world.get_parent(*e)?;
            Ok(parent.map(Val))
        })

The new version make things much more simple to apprehend and everything, so far it's a lot easier to work with.
I have some questions about adding bindings,

Glad to hear it!

[aurreland]

Finally managed to get it working, thanks for the snippet it was helpful. I think it would be cool if one of the example in the docs used world.with_global_access as it shows how to do things like commands or anything.

This is my resulting function for now :

fn add_lua_bindings(app: &mut App) -> &mut App {
    let world = app.world_mut();

    NamespaceBuilder::<GlobalNamespace>::new_unregistered(world).register(
        "add_mesh3d",
        |ctx: FunctionCallContext, entity: Val<Entity>, mesh_type: String, values: ScriptValue| {
            let world = ctx.world()?;
            world.with_global_access(|world| {
                let entity = entity.into_inner();
                let mut meshes = world.resource_mut::<Assets<Mesh>>();
                let mesh_type = match mesh_type.as_str() {
                    _ => {
                        let radius = match values {
                            ScriptValue::Float(r) => r as f32,
                            ScriptValue::Integer(r) => r as f32,
                            _ => 0.1
                        };
                        Sphere::new(radius)
                    },
                };
                let mesh_handle = meshes.add(mesh_type);
                let mut materials = world.resource_mut::<Assets<StandardMaterial>>();
                let material = materials.add(StandardMaterial::default());
                world.commands().entity(entity).insert((
                    Mesh3d(mesh_handle),
                    MeshMaterial3d(material)
                ));
                Ok(())
            })?
        },
    );
    app
}

Thanks for the help, the new way to work with the crate is definitely better, nice additions. ScriptValue makes it really easy to work with differents type too.