add command line options for help, and for setting window mode

src/main.rs

@@ -32,11 +32,32 @@ use bevy::prelude::*;
 use bevy::pbr::ExtendedMaterial;
 use std::env;
 
+const HELP: &str = "./outfly [options]
+
+Options:
+  --version, -v  show this program's version number and exit
+  --help, -h     show this help message and exit
+  --gl           use GL rendering instead of Vulkan
+  --fs-legacy    use 'legacy' (non-borderless) fullscreen mode
+  --fs-sized     use 'sized' (non-borderless) fullscreen mode
+  --windowed     start in non-fullscreen mode
+
+Note: borderless fullscreen is the default, but it crashes on some systems.";
+
 fn main() {
+    let mut opt = CommandLineOptions {
+        window_mode_fullscreen: WindowMode::BorderlessFullscreen,
+        window_mode_initial: WindowMode::BorderlessFullscreen,
+    };
+
     let args: Vec<String> = env::args().collect();
     if args.len() > 1 {
         for arg in &args[1..] {
-            if arg == "--version" || arg == "-v" {
+            if arg == "--help" || arg == "-h" {
+                println!("{}", HELP);
+                return;
+            }
+            else if arg == "--version" || arg == "-v" {
                 let version = option_env!("CARGO_PKG_VERSION").unwrap();
                 let name = option_env!("CARGO_PKG_NAME").unwrap();
                 let homepage = option_env!("CARGO_PKG_HOMEPAGE").unwrap();
@@ -48,13 +69,38 @@ fn main() {
             else if arg == "--gl" {
                 env::set_var("WGPU_BACKEND", "gl");
             }
+            else if arg == "--windowed" {
+                opt.window_mode_initial = WindowMode::Windowed;
+            }
+            else if arg == "--fs-legacy" {
+                let mode = WindowMode::Fullscreen;
+                if opt.window_mode_initial == opt.window_mode_fullscreen {
+                    opt.window_mode_initial = mode;
+                }
+                opt.window_mode_fullscreen = mode;
+            }
+            else if arg == "--fs-sized" {
+                let mode = WindowMode::SizedFullscreen;
+                if opt.window_mode_initial == opt.window_mode_fullscreen {
+                    opt.window_mode_initial = mode;
+                }
+                opt.window_mode_fullscreen = mode;
+            }
+            else {
+                println!("{}", HELP);
+                println!("\nERROR: no such option: `{}`", arg);
+                return;
+            }
         }
     }
     let mut app = App::new();
+    app.insert_resource(opt);
+
     #[cfg(feature = "embed_assets")]
     app.add_plugins(bevy_embedded_assets::EmbeddedAssetPlugin {
         mode: bevy_embedded_assets::PluginMode::ReplaceDefault
     });
+
     app.add_plugins(OutFlyPlugin).run();
 }
 
@@ -84,13 +130,20 @@ impl Plugin for OutFlyPlugin {
     }
 }
 
+#[derive(Resource, Default)]
+pub struct CommandLineOptions {
+    window_mode_fullscreen: WindowMode,
+    window_mode_initial: WindowMode,
+}
+
 fn setup(
     mut windows: Query<&mut Window, With<PrimaryWindow>>,
+    opt: Res<CommandLineOptions>,
 ) {
     for mut window in &mut windows {
         window.cursor.grab_mode = CursorGrabMode::Locked;
         window.cursor.visible = false;
-        window.mode = WindowMode::BorderlessFullscreen;
+        window.mode = opt.window_mode_initial;
         window.title = "OutFly".to_string();
     }
 }
@@ -98,6 +151,7 @@ fn setup(
 fn handle_input(
     keyboard_input: Res<ButtonInput<KeyCode>>,
     settings: Res<var::Settings>,
+    opt: Res<CommandLineOptions>,
     mut app_exit_events: ResMut<Events<bevy::app::AppExit>>,
     mut windows: Query<&mut Window, With<PrimaryWindow>>,
 ) {
@@ -107,7 +161,7 @@ fn handle_input(
     if keyboard_input.just_pressed(settings.key_fullscreen) {
         for mut window in &mut windows {
             window.mode = if window.mode == WindowMode::Windowed {
-                WindowMode::BorderlessFullscreen
+                opt.window_mode_fullscreen
             } else {
                 WindowMode::Windowed
             }