add: preload scripts (#6)

examples/preload_scripts.rs

@@ -0,0 +1,44 @@
+//! You can use [`PreloadScripts`] to execute scripts when the webview is initialized.
+//!
+//! [`PreloadScripts`] is executed before the scripts in the HTML.
+
+use bevy::prelude::*;
+use bevy_cef::prelude::*;
+
+fn main() {
+    App::new()
+        .add_plugins((DefaultPlugins, CefPlugin))
+        .add_systems(
+            Startup,
+            (spawn_camera, spawn_directional_light, spawn_webview),
+        )
+        .run();
+}
+
+fn spawn_camera(mut commands: Commands) {
+    commands.spawn((
+        Camera3d::default(),
+        Transform::from_translation(Vec3::new(0., 0., 3.)).looking_at(Vec3::ZERO, Vec3::Y),
+    ));
+}
+
+fn spawn_directional_light(mut commands: Commands) {
+    commands.spawn((
+        DirectionalLight::default(),
+        Transform::from_translation(Vec3::new(1., 1., 1.)).looking_at(Vec3::ZERO, Vec3::Y),
+    ));
+}
+
+fn spawn_webview(
+    mut commands: Commands,
+    mut meshes: ResMut<Assets<Mesh>>,
+    mut materials: ResMut<Assets<WebviewExtendStandardMaterial>>,
+) {
+    commands.spawn((
+        CefWebviewUri::new("https://github.com/not-elm/bevy_cef"),
+        Mesh3d(meshes.add(Plane3d::new(Vec3::Z, Vec2::ONE))),
+        MeshMaterial3d(materials.add(WebviewExtendStandardMaterial::default())),
+        // Here, we add a simple script to show an alert.
+        PreloadScripts::from(["alert('Hello World!')"]),
+    ));
+}