Display FPS in hud (copied from example)

src/hud.rs

@@ -0,0 +1,58 @@
+use bevy::{
+  diagnostic::{Diagnostics, FrameTimeDiagnosticsPlugin},
+  prelude::*,
+};
+
+pub struct HudPlugin;
+
+impl Plugin for HudPlugin {
+  fn build(&self, app: &mut AppBuilder) {
+    app
+      .add_plugin(FrameTimeDiagnosticsPlugin::default())
+      .add_startup_system(setup.system())
+      .add_system(fps_update_system.system());
+  }
+}
+
+// A unit struct to help identify the FPS UI component, since there may be many Text components
+struct FpsText;
+
+fn fps_update_system(diagnostics: Res<Diagnostics>, mut query: Query<&mut Text, With<FpsText>>) {
+  for mut text in query.iter_mut() {
+    if let Some(fps) = diagnostics.get(FrameTimeDiagnosticsPlugin::FPS) {
+      if let Some(average) = fps.value() {
+        text.value = format!("{:.0} fps", average);
+      }
+    }
+  }
+}
+
+fn setup(commands: &mut Commands, asset_server: Res<AssetServer>) {
+  commands
+    // UI camera
+    .spawn(CameraUiBundle::default())
+    // texture
+    .spawn(TextBundle {
+      style: Style {
+        align_self: AlignSelf::FlexEnd,
+        position_type: PositionType::Absolute,
+        position: Rect {
+          top: Val::Px(5.0),
+          right: Val::Px(5.0),
+          ..Default::default()
+        },
+        ..Default::default()
+      },
+      text: Text {
+        value: "".to_string(),
+        font: asset_server.load("fonts/FiraMono-Medium.ttf"),
+        style: TextStyle {
+          font_size: 16.0,
+          color: Color::WHITE,
+          ..Default::default()
+        },
+      },
+      ..Default::default()
+    })
+    .with(FpsText);
+}

src/lib.rs

@@ -1,2 +1,3 @@
+pub mod hud;
 pub mod player;
 pub mod world;

src/main.rs

@@ -1,6 +1,6 @@
 use bevy::{input::system::exit_on_esc_system, prelude::*};
 use bevy_rapier3d::physics::RapierPhysicsPlugin;
-use rake::{player::PlayerPlugin, world::WorldPlugin};
+use rake::{hud::HudPlugin, player::PlayerPlugin, world::WorldPlugin};
 
 fn main() {
   App::build()
@@ -16,6 +16,7 @@ fn main() {
     // note: debug renderer doesnt work for cylinder
     //.add_plugin(RapierRenderPlugin)
     .add_plugin(PlayerPlugin)
+    .add_plugin(HudPlugin)
     .add_plugin(WorldPlugin)
     .add_system(exit_on_esc_system.system())
     .run();