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src/engine.rs

@@ -1,17 +1,16 @@
-use std::time::Duration;
+use std::{path::Component, time::Duration};
 
 use sdl2::{
-    event::Event, keyboard::Keycode, pixels::Color, render::Canvas, video::Window, Sdl,
-    VideoSubsystem,
+    event::Event,
+    image::{self, LoadTexture, Sdl2ImageContext},
+    keyboard::Keycode,
+    pixels::Color,
+    rect::Rect,
+    render::{Canvas, Texture, TextureCreator},
+    video::{Window, WindowBuildError, WindowContext},
+    IntegerOrSdlError, Sdl, VideoSubsystem,
 };
 
-pub struct Game {
-    sdl_context: Sdl,
-    video_subsystem: VideoSubsystem,
-    canvas: Canvas<Window>,
-    event_pump: sdl2::EventPump,
-}
-
 #[derive(Debug, Clone)]
 pub struct Error(String);
 
@@ -21,29 +20,143 @@ impl std::fmt::Display for Error {
     }
 }
 
-impl<T: std::fmt::Display> From<T> for Error {
-    fn from(value: T) -> Self {
+macro_rules! impl_from_T_for_Error {
+    ($t:ty) => {
+        impl From<$t> for Error {
+            fn from(value: $t) -> Self {
                 Self(value.to_string())
             }
+        }
+    };
+    ($t:ty, $($ts:ty),+) => {
+        impl From<$t> for Error {
+            fn from(value: $t) -> Self {
+                Self(value.to_string())
+            }
+        }
+        impl_from_T_for_Error!($($ts),+);
+    };
+}
+
+impl_from_T_for_Error!(String, WindowBuildError, IntegerOrSdlError);
+
+static RANDOM_U64_COUNTER: u64 = 0;
+
+pub struct Entity(u64);
+
+pub trait Component {}
+
+pub struct Sprite<'a> {
+    texture: Texture<'a>,
+}
+
+pub struct Context<'a> {
+    id_counter: &'a mut u64,
+    canvas: &'a mut Canvas<Window>,
+    texture_creator: &'a TextureCreator<WindowContext>,
+    entities: &'a mut Vec<Entity>,
+    components: &'a mut Vec<(u64, Box<dyn Component>)>,
+    systems: &'a mut Vec<Box<dyn System>>,
+}
+
+impl<'a> Context<'a> {
+    pub fn load_sprite<'b, P>(&self, path: P) -> Result<Sprite<'b>, Error>
+    where
+        'a: 'b,
+        P: AsRef<std::path::Path>,
+    {
+        let texture = self.texture_creator.load_texture(path)?;
+        Ok(Sprite { texture })
+    }
+
+    pub fn draw_sprite<'b>(&mut self, sprite: &Sprite<'b>, x: i32, y: i32) -> Result<(), Error> {
+        self.canvas.copy(
+            &sprite.texture,
+            None,
+            Rect::new(
+                x * 4,
+                y * 4,
+                sprite.texture.query().width * 4,
+                sprite.texture.query().height * 4,
+            ),
+        )?;
+        Ok(())
+    }
+
+    pub fn spawn(&mut self, components: Vec<Box<dyn Component>>) {
+        let id = *self.id_counter;
+        *self.id_counter += 1;
+        self.entities.push(Entity(id));
+        self.components
+            .extend(components.into_iter().map(|component| (id, component)));
+    }
+
+    pub fn add_system(&mut self, system: Box<dyn System>) {
+        system.on_add(self);
+        self.systems.push(system)
+    }
+
+    pub fn query<F: Fn(u64) -> bool>(&mut self, predicate: F) -> Vec<u64> {
+        let mut entities = Vec::<u64>::new();
+        for entity in &mut *self.entities {
+            if predicate(entity.0) {
+                entities.push(entity.0)
+            }
+        }
+        entities
+    }
+
+    pub fn has_component<T>(&mut self, entity_id: u64) -> bool {
+        for (id, component) in self.components {}
+    }
+}
+
+pub trait System {
+    fn on_add(&self, _ctx: &mut Context) {}
+    fn on_update(&self, _ctx: &mut Context) {}
+}
+
+pub struct Game {
+    id_counter: u64,
+    sdl_context: Sdl,
+    video_subsystem: VideoSubsystem,
+    image_context: Sdl2ImageContext,
+    canvas: Canvas<Window>,
+    texture_creator: TextureCreator<WindowContext>,
+    event_pump: sdl2::EventPump,
+    entities: Vec<Entity>,
+    components: Vec<(u64, Box<dyn Component>)>,
+    systems: Vec<Box<dyn System>>,
 }
 
 impl Game {
     pub fn new() -> Result<Self, Error> {
         let sdl_context = sdl2::init()?;
         let video_subsystem = sdl_context.video()?;
+        let image_context = image::init(image::InitFlag::PNG)?;
         let window = video_subsystem
             .window("pvp-game-dilapidation", 1280, 720)
             .position_centered()
             .build()?;
+
         let mut canvas = window.into_canvas().build()?;
+        let texture_creator = canvas.texture_creator();
+
         canvas.set_draw_color(Color::RGB(60, 180, 180));
         canvas.clear();
+        canvas.present();
         let event_pump = sdl_context.event_pump()?;
         Ok(Self {
+            id_counter: 0,
             sdl_context,
             video_subsystem,
+            image_context,
             canvas,
+            texture_creator,
             event_pump,
+            entities: vec![],
+            components: vec![],
+            systems: vec![],
         })
     }
 
@@ -64,4 +177,15 @@ impl Game {
         self.canvas.present();
         std::thread::sleep(Duration::new(0, 1_000_000_000u32 / 60))
     }
+
+    pub fn context<'a>(&'a mut self) -> Context<'a> {
+        Context {
+            id_counter: &mut self.id_counter,
+            canvas: &mut self.canvas,
+            texture_creator: &self.texture_creator,
+            entities: &mut self.entities,
+            components: &mut self.components,
+            systems: &mut self.systems,
+        }
+    }
 }

src/main.rs

@@ -1,8 +1,35 @@
-#[allow(dead_code)]
+#![allow(dead_code)]
+
+use engine::{Component, Sprite, System};
 mod engine;
 
-fn main() {
-    let game = engine::Game::new().unwrap();
-    game.run();
-    println!("Hello, world!");
+struct Player<'a> {
+    sprite: Option<Sprite<'a>>,
+}
+
+impl<'a> Component for Player<'a> {}
+
+struct PlayerRenderer;
+
+impl System for PlayerRenderer {
+    fn on_add(&self, ctx: &mut engine::Context) {
+        for entity in ctx.query(|id| ) {}
+    }
+
+    fn on_update(&self, _ctx: &mut engine::Context) {}
+}
+
+fn main() {
+    let mut game = engine::Game::new().unwrap();
+
+    {
+        let mut context = game.context();
+        context.add_system(Box::new(PlayerRenderer));
+        context.spawn(vec![Box::new(Player { sprite: None })]);
+
+        // let sprite = context.load_sprite("textures/player.png").unwrap();
+        // context.draw_sprite(&sprite, 16, 16).unwrap();
+    }
+
+    game.run();
 }