added fps counter

src/main.rs

@@ -26,6 +26,9 @@ fn main() {
     // Create app
     let mut app = futures::executor::block_on(App::new(&window));
 
+    let mut fps_timer = std::time::Instant::now();
+    let mut fps_counter = 0;
+
     // Run event loop
     events.run(move |e, _, c| {
         match e {
@@ -64,9 +67,22 @@ fn main() {
             }
             // Draw
             Event::RedrawRequested(_) => {
+
+                // Display FPS
+                let elapsed = fps_timer.elapsed().as_millis();
+                if elapsed >= 1000 {
+                    let elapsed_sec = (elapsed as f32) / 1000.0;
+                    let fps = (fps_counter as f32) / elapsed_sec;
+                    println!("FPS: {}", fps);
+                    fps_timer = std::time::Instant::now();
+                    fps_counter = 0;
+                }
+                fps_counter += 1;
+                
+                // Update and Render
                 app.update();
                 match app.render() {
-                    Ok(_) => {}
+                    Ok(_) => { }
                     // Recreate the swap_chain if lost
                     Err(wgpu::SwapChainError::Lost) => app.resize(None),
                     // The system is out of memory, we should probably quit