Single-object viewer POC (#14)

This commit implements a Sketchfab-style single-object viewer as a minimal
proof-of-concept.

### `@storyteller/studio-web`
This is a new package to house web components for interfacing with the
`@storyteller/studio` WASM library. It currently includes a single component,
`<sts-viewer />`, which is exported from `@storyteller/studio-web/viewer`.

### `react-frontend`
This is a new application intended as a proof-of-concept and testbed for React
interop with `@storyteller/studio-web`.

Web components are currently a little bit fiddly to use in a React application.
`react-frontend/src/app/studio-viewer.tsx` demonstrates how a React-idiomatic
component can be written as a thin wrapper around a web component, and
`react-frontend/src/app/app.tsx` demonstrates that wrapper component in use.

studio/src/lib.rs

@@ -2,27 +2,36 @@
 
 use bevy::prelude::*;
 use bevy_mod_picking::DefaultPickingPlugins;
-use camera_controller::CameraControllerPlugin;
-use debug::DebugPlugin;
-use input::StudioInputPlugin;
-use interaction::InteractionPlugin;
-use math::InterpolationPlugin;
-use scene::ScenePlugin;
-use skybox::SkyboxPlugin;
-use ui::UiLayerPlugin;
-use viewport::ViewportSize;
+
+#[cfg(feature = "wasm")]
 use wasm_bindgen::prelude::*;
 
 mod camera_controller;
 mod debug;
 mod design_system;
 mod input;
+mod inspector;
 mod interaction;
 mod math;
 mod scene;
 mod skybox;
 mod ui;
 mod viewport;
+mod world_grid;
+
+use crate::{
+    camera_controller::CameraControllerPlugin,
+    debug::DebugPlugin,
+    input::StudioInputPlugin,
+    inspector::InspectorPlugin,
+    interaction::InteractionPlugin,
+    math::InterpolationPlugin,
+    scene::{LoadSceneEvent, ScenePlugin},
+    skybox::{SkyboxId, SkyboxPlugin},
+    ui::UiLayerPlugin,
+    viewport::ViewportSize,
+    world_grid::WorldGridPlugin,
+};
 
 #[cfg(feature = "wasm")]
 mod wasm;
@@ -30,7 +39,7 @@ mod wasm;
 #[derive(Component)]
 pub(crate) struct MainCamera;
 
-#[wasm_bindgen]
+#[cfg_attr(feature = "wasm", wasm_bindgen)]
 pub fn init(viewport_size: ViewportSize) {
     #[cfg(feature = "wasm")]
     console_error_panic_hook::set_once();
@@ -62,12 +71,80 @@ pub fn init(viewport_size: ViewportSize) {
         DefaultPickingPlugins,
         DebugPlugin,
         InteractionPlugin,
+        InspectorPlugin,
         StudioInputPlugin,
         InterpolationPlugin,
         CameraControllerPlugin,
         ScenePlugin,
         SkyboxPlugin,
         UiLayerPlugin,
-    ))
-    .run();
+        WorldGridPlugin,
+    ));
+
+    #[cfg(feature = "wasm")]
+    wasm::initialize();
+
+    app.run();
+}
+
+#[cfg_attr(feature = "wasm", wasm_bindgen(js_name = startViewer))]
+/// Start the application as a read-only viewer for a single library object.
+///
+/// @param object_id ID of the library object to load.
+/// @param skybox_id ID of the Skybox to use
+/// @param canvas_selector A CSS selector for the canvas that will host the Bevy
+///   application. This should be unique (i.e. `querySelectorAll` should not
+///   return more than one element), so using an ID selector is a good idea.
+/// @param canvas_alt `alt` text for the HTML canvas element.
+/// @param viewport_size The size of the canvas in CSS `px` units.
+pub fn start_viewer(
+    object_id: &str,
+    skybox_id: &str,
+    canvas_selector: &str,
+    canvas_alt: &str,
+    viewport_size: ViewportSize,
+) {
+    #[cfg(feature = "wasm")]
+    console_error_panic_hook::set_once();
+
+    let object_id = object_id.to_string();
+    let skybox_id = skybox_id.to_string();
+
+    let mut app = App::new();
+    app.add_plugins((
+        #[cfg(feature = "wasm")]
+        viewport::wasm::ViewportPlugin,
+        DefaultPlugins.set(WindowPlugin {
+            primary_window: Some(Window {
+                resolution: viewport_size.into(),
+                title: canvas_alt.into(),
+                canvas: Some(canvas_selector.into()),
+                ..default()
+            }),
+            ..default()
+        }),
+        DefaultPickingPlugins,
+        DebugPlugin,
+        InteractionPlugin,
+        InspectorPlugin,
+        StudioInputPlugin,
+        InterpolationPlugin,
+        CameraControllerPlugin,
+        ScenePlugin,
+        SkyboxPlugin,
+        UiLayerPlugin,
+        WorldGridPlugin,
+    ))
+    .add_systems(
+        Startup,
+        move |mut cmd: Commands, mut ew: EventWriter<LoadSceneEvent>| {
+            cmd.insert_resource(SkyboxId(skybox_id.clone()));
+            ew.send(LoadSceneEvent(object_id.clone()));
+        },
+    );
+
+    #[cfg(feature = "wasm")]
+    wasm::initialize();
+
+    app.run();
 }