Voxygen list backends subcommand

voxygen/src/cli.rs

@@ -7,7 +7,7 @@
 //!
 //! Airshipper should only use arguments listed above! Since we will not try to
 //! be careful about their stability otherwise.
-use clap::Parser;
+use clap::{Parser, Subcommand};
 
 #[derive(Parser)]
 pub struct Args {
@@ -16,4 +16,13 @@ pub struct Args {
     /// This allows passing in server selection performed in airshipper.
     #[clap(short, long)]
     pub server: Option<String>,
+
+    #[clap(subcommand)]
+    pub command: Option<Commands>,
+}
+
+#[derive(Subcommand)]
+pub enum Commands {
+    /// List available wgpu backends.
+    ListBackends,
 }

voxygen/src/main.rs

@@ -42,6 +42,28 @@ use tracing::{info, warn};
 use veloren_voxygen::ui::egui::EguiState;
 
 fn main() {
+    // Process CLI arguments
+    use clap::Parser;
+    let args = cli::Args::parse();
+
+    if let Some(command) = args.command {
+        match command {
+            cli::Commands::ListBackends => {
+                #[cfg(target_os = "windows")]
+                let backends = &["dx11", "dx12", "vulkan"];
+                #[cfg(target_os = "linux")]
+                let backends = &["vulkan"];
+                #[cfg(target_os = "macos")]
+                let backends = &["metal"];
+
+                for backend in backends {
+                    println!("{backend}");
+                }
+                return;
+            },
+        }
+    }
+
     #[cfg(feature = "tracy")]
     common_base::tracy_client::Client::start();
 
@@ -93,10 +115,6 @@ fn main() {
 
     panic_handler::set_panic_hook(log_filename, logs_dir);
 
-    // Process CLI arguments
-    use clap::Parser;
-    let args = cli::Args::parse();
-
     // Setup tokio runtime
     use common::consts::MIN_RECOMMENDED_TOKIO_THREADS;
     use std::sync::{