Macro aframe::component_struct

macro_rules! component_struct {
    ($(#[$outer:meta])* $name:ident $(, $field:ident: $field_name:literal $ty:ty = $default:expr)*) => { ... };
    ($(#[$outer:meta])* $name:ident $(:$alt:ident)? $fmt:expr $(, $field:ident: $field_name:literal $ty:ty = $default:expr)*) => { ... };
}

While component_def! creates a component that Aframe can access from its own runtime, the component_struct! macro creates a Rust struct that mimics the internal details of that Aframe component. Component structs are already provided for Aframe’s built-in components (WIP: not all components are defined yet. Once all aframe components are defined, calling component_struct! should only be necessary for locally-defined components. Once all components from Aframe have been defined, component_def! and component_struct! may be merged into a single macro to do the heavy-lifting of both at once). The component must be already registered in aframe before this struct may be used (although constructing it before that is safe). There are 2 variation of syntax provided, depending on the desired resulting Display implementation.

use aframe::component_struct;
 
// Example 1, uses hard-coded display implementation:
component_struct!
{
    /// Doc comment for StructName
    StructName, 
    field_1: "field1Name" f32 = 1.5,
    field_2: "field2Name" bool = false
}

// This will display as: "field1Name: 1.5; field2Name: false"

// Example 2, uses custom display implementation:
component_struct!{Vec3 "{} {} {}", 
    x: f32 = 1.0,
    y: f32 = 1.5,
    z: f32 = 2.0
}
 
// This will display as "1.0 1.5 2.0"

When using items defined with this macro or with the complex_enum! macro as fields, a custom display implementation may be used to flatten out the nested properties and print correctly as a single semicolon-separated list of properties.