game: Create more stages and generalize them

lyra-game/src/delta_time.rs

@@ -1,7 +1,7 @@
 use instant::Instant;
 use lyra_ecs::{Component, world::World};
 
-use crate::plugin::Plugin;
+use crate::{plugin::Plugin, game::GameStages};
 
 #[derive(Clone, Component)]
 pub struct DeltaTime(f32, Option<Instant>);
@@ -20,7 +20,10 @@ impl std::ops::DerefMut for DeltaTime {
     }
 }
 
-fn delta_time_system(world: &mut World) -> anyhow::Result<()> {
+/// A system that updates the [`DeltaTime``] resource.
+/// 
+/// The resource is updated in the [`GameStages::First`] stage.
+pub fn delta_time_system(world: &mut World) -> anyhow::Result<()> {
     let now = Instant::now();
     let mut delta = world.get_resource_mut::<DeltaTime>();
     delta.0 = delta.1.unwrap_or(now).elapsed().as_secs_f32();
@@ -34,6 +37,6 @@ pub struct DeltaTimePlugin;
 impl Plugin for DeltaTimePlugin {
     fn setup(&self, game: &mut crate::game::Game) {
         game.world().add_resource(DeltaTime(0.0, None));
-        game.with_system("delta_time", delta_time_system, &[]);
+        game.add_system_to_stage(GameStages::First, "delta_time", delta_time_system, &[]);
     }
 }

lyra-game/src/game.rs

@@ -17,8 +17,16 @@ use crate::{render::{renderer::{Renderer, BasicRenderer}, window::WindowOptions}
 
 #[derive(Clone, Copy, Hash, Debug)]
 pub enum GameStages {
-    Core,
-    User,
+    /// This stage runs before all other stages.
+    First,
+    /// This stage runs before `Update`.
+    PreUpdate,
+    /// This stage is where most game logic would be.
+    Update,
+    /// This stage is ran after `Update`.
+    PostUpdate,
+    /// This stage runs after all other stages.
+    Last,
 }
 
 impl Stage for GameStages {}
@@ -217,8 +225,11 @@ pub struct Game {
 impl Default for Game {
     fn default() -> Self {
         let mut staged = StagedExecutor::new();
-        staged.add_stage(GameStages::Core);
-        staged.add_stage_after(GameStages::Core, GameStages::User);
+        staged.add_stage(GameStages::First);
+        staged.add_stage_after(GameStages::First, GameStages::PreUpdate);
+        staged.add_stage_after(GameStages::PreUpdate, GameStages::Update);
+        staged.add_stage_after(GameStages::Update, GameStages::PostUpdate);
+        staged.add_stage_after(GameStages::PostUpdate, GameStages::Last);
 
         Self {
             world: Some(World::new()),
@@ -247,7 +258,7 @@ impl Game {
         <S as IntoSystem<A>>::System: 'static
     {
         let system_dispatcher = self.system_exec.as_mut().unwrap();
-        system_dispatcher.add_system_to_stage(GameStages::User, name, system.into_system(), depends);
+        system_dispatcher.add_system_to_stage(GameStages::Update, name, system.into_system(), depends);
 
         self
     }
@@ -278,8 +289,13 @@ impl Game {
     /// 
     /// # Panics
     /// Panics if the stage was not already added to the executor
-    pub fn add_system_to_stage<ST: Stage, I: IntoSystem<()> + 'static>(&mut self, stage: ST,
-            name: &str, system: I, depends: &[&str]) -> &mut Self {
+    pub fn add_system_to_stage<T, S, A>(&mut self, stage: T,
+            name: &str, system: S, depends: &[&str]) -> &mut Self
+    where
+        T: Stage,
+        S: IntoSystem<A>,
+        <S as IntoSystem<A>>::System: 'static
+    {
         let system_dispatcher = self.system_exec.as_mut().unwrap();
         system_dispatcher.add_system_to_stage(stage, name, system.into_system(), depends);
 

lyra-game/src/input/action.rs

@@ -2,7 +2,7 @@ use std::{collections::HashMap, ops::Deref};
 
 use lyra_ecs::world::World;
 
-use crate::plugin::Plugin;
+use crate::{plugin::Plugin, game::GameStages};
 
 use super::{Button, KeyCode, InputButtons};
 
@@ -392,6 +392,6 @@ pub struct InputActionPlugin;
 
 impl Plugin for InputActionPlugin {
     fn setup(&self, game: &mut crate::game::Game) {
-        game.with_system("input_actions", actions_system, &[]);
+        game.add_system_to_stage(GameStages::PreUpdate, "input_actions", actions_system, &[]);
     }
 }

lyra-game/src/input/system.rs

@@ -4,7 +4,7 @@ use glam::Vec2;
 use lyra_ecs::{world::World, system::IntoSystem};
 use winit::event::MouseScrollDelta;
 
-use crate::{EventQueue, plugin::Plugin};
+use crate::{EventQueue, plugin::Plugin, game::GameStages};
 
 use super::{events::*, InputButtons, InputEvent};
 
@@ -136,6 +136,6 @@ pub struct InputPlugin;
 
 impl Plugin for InputPlugin {
     fn setup(&self, game: &mut crate::game::Game) {
-        game.with_system("input", InputSystem, &[]);
+        game.add_system_to_stage(GameStages::PreUpdate, "input", InputSystem, &[]);
     }
 }