Refactor SpriteCache and animation (#3)

* Refactor SpriteCache and animations

- Animation frames are now enumerated
- Renamed the `Sprites` trait into the more apt `Drawable`
- Moved animation to a default impl on `Drawable`
- Added the Cthulhu invader
- Clarify that `World::step_invaders()` is only needed for handling the invader grid
- Renamed `Cannon` to `Bullet`

* Improve readability of some `SpriteCache` uses.

simple-invaders/src/lib.rs

@@ -8,7 +8,7 @@ use std::time::Duration;
 
 pub use controls::{Controls, Direction};
 use loader::{load_assets, Assets};
-use sprites::{blit, Sprite, SpriteRef, Sprites};
+use sprites::{blit, Drawable, Frame, Sprite, SpriteRef};
 
 mod controls;
 mod loader;
@@ -31,7 +31,7 @@ pub struct World {
     lasers: Vec<Laser>,
     shields: Vec<Shield>,
     player: Player,
-    cannons: Vec<Cannon>,
+    bullets: Vec<Bullet>,
     score: u32,
     assets: Assets,
     screen: Vec<u8>,
@@ -103,7 +103,7 @@ struct Laser {
 
 /// The cannon entity.
 #[derive(Debug)]
-struct Cannon {
+struct Bullet {
     sprite: SpriteRef,
     pos: Point,
 }
@@ -111,6 +111,8 @@ struct Cannon {
 impl World {
     /// Create a new simple-invaders `World`.
     pub fn new() -> World {
+        use Frame::*;
+
         // Load assets first
         let assets = load_assets();
 
@@ -120,12 +122,12 @@ impl World {
             bounds: Bounds::default(),
         };
         let player = Player {
-            sprite: SpriteRef::new(&assets, "player1"),
+            sprite: SpriteRef::new(&assets, Player1),
             pos: Point::new(80, 216),
         };
         let shields = (0..4)
             .map(|i| Shield {
-                sprite: Sprite::new(&assets, "shield"),
+                sprite: Sprite::new(&assets, Shield1),
                 pos: Point::new(i * 45 + 32, 192),
             })
             .collect();
@@ -139,7 +141,7 @@ impl World {
             lasers: Vec::new(),
             shields,
             player,
-            cannons: Vec::new(),
+            bullets: Vec::new(),
             score: 0,
             assets,
             screen,
@@ -153,17 +155,21 @@ impl World {
     ///
     /// * `dt`: The time delta since last update.
     /// * `controls`: The player inputs.
-    pub fn update(&mut self, dt: Duration, controls: Controls) {
+    pub fn update(&mut self, dt: Duration, _controls: Controls) {
         let one_frame = Duration::new(0, 16_666_667);
 
         // Advance the timer by the delta time
         self.timing += dt;
 
-        // Step the game logic by one frame at a time
+        // Step the invaders one by one
         while self.timing >= one_frame {
             self.timing -= one_frame;
-            self.step(&controls);
+            self.step_invaders();
         }
+
+        // TODO: Handle controls to move the player
+        // TODO: Handle lasers and bullets
+        // Movements can be multiplied by the delta-time frame count, instead of looping
     }
 
     /// Draw the internal state to the screen.
@@ -183,7 +189,7 @@ impl World {
         &self.screen
     }
 
-    fn step(&mut self, _controls: &Controls) {
+    fn step_invaders(&mut self) {
         // Find the next invader
         let mut invader = None;
         while let None = invader {
@@ -192,18 +198,10 @@ impl World {
         }
         let invader = invader.unwrap();
 
-        // Animate the invader
-        let assets = self.assets.sprites();
-        let (pixels, frame) = match invader.sprite.frame().as_ref() {
-            "blipjoy1" => (assets.get("blipjoy2").unwrap().2.clone(), "blipjoy2"),
-            "blipjoy2" => (assets.get("blipjoy1").unwrap().2.clone(), "blipjoy1"),
-            "ferris1" => (assets.get("ferris2").unwrap().2.clone(), "ferris2"),
-            "ferris2" => (assets.get("ferris1").unwrap().2.clone(), "ferris1"),
-            _ => unreachable!(),
-        };
+        // TODO: Move the invader
 
-        invader.sprite.update_pixels(pixels);
-        invader.sprite.update_frame(frame);
+        // Animate the invader
+        invader.sprite.animate(&self.assets);
     }
 
     /// Clear the screen
@@ -279,6 +277,8 @@ impl Default for Bounds {
 
 /// Create a grid of invaders.
 fn make_invader_grid(assets: &Assets) -> Vec<Vec<Option<Invader>>> {
+    use Frame::*;
+
     const BLIPJOY_OFFSET: Point = Point::new(3, 4);
     const FERRIS_OFFSET: Point = Point::new(3, 5);
 
@@ -287,7 +287,7 @@ fn make_invader_grid(assets: &Assets) -> Vec<Vec<Option<Invader>>> {
             (0..COLS)
                 .map(|x| {
                     Some(Invader {
-                        sprite: SpriteRef::new(assets, "blipjoy1"),
+                        sprite: SpriteRef::new(assets, Blipjoy1),
                         pos: START + BLIPJOY_OFFSET + Point::new(x, y) * GRID,
                         score: 10,
                     })
@@ -298,7 +298,7 @@ fn make_invader_grid(assets: &Assets) -> Vec<Vec<Option<Invader>>> {
             (0..COLS)
                 .map(|x| {
                     Some(Invader {
-                        sprite: SpriteRef::new(assets, "ferris1"),
+                        sprite: SpriteRef::new(assets, Ferris1),
                         pos: START + FERRIS_OFFSET + Point::new(x, y) * GRID,
                         score: 10,
                     })
@@ -309,8 +309,7 @@ fn make_invader_grid(assets: &Assets) -> Vec<Vec<Option<Invader>>> {
             (0..COLS)
                 .map(|x| {
                     Some(Invader {
-                        // TODO: Need a third invader
-                        sprite: SpriteRef::new(assets, "blipjoy1"),
+                        sprite: SpriteRef::new(assets, Cthulhu1),
                         pos: START + BLIPJOY_OFFSET + Point::new(x, y) * GRID,
                         score: 10,
                     })

simple-invaders/src/loader.rs

@@ -2,55 +2,43 @@ use std::collections::HashMap;
 use std::io::Cursor;
 use std::rc::Rc;
 
-use crate::sprites::CachedSprite;
+use crate::sprites::{CachedSprite, Frame};
 
 /// A list of assets loaded into memory.
 #[derive(Debug)]
 pub(crate) struct Assets {
     // sounds: TODO
-    sprites: HashMap<String, CachedSprite>,
+    sprites: HashMap<Frame, CachedSprite>,
 }
 
 impl Assets {
-    pub(crate) fn sprites(&self) -> &HashMap<String, CachedSprite> {
+    pub(crate) fn sprites(&self) -> &HashMap<Frame, CachedSprite> {
         &self.sprites
     }
 }
 
 /// Load all static assets into an `Assets` structure
 pub(crate) fn load_assets() -> Assets {
+    use Frame::*;
+
     let mut sprites = HashMap::new();
 
-    sprites.insert(
-        "blipjoy1".into(),
-        load_pcx(include_bytes!("assets/blipjoy1.pcx")),
-    );
-    sprites.insert(
-        "blipjoy2".into(),
-        load_pcx(include_bytes!("assets/blipjoy2.pcx")),
-    );
-    sprites.insert(
-        "ferris1".into(),
-        load_pcx(include_bytes!("assets/ferris1.pcx")),
-    );
-    sprites.insert(
-        "ferris2".into(),
-        load_pcx(include_bytes!("assets/ferris2.pcx")),
-    );
-    sprites.insert(
-        "player1".into(),
-        load_pcx(include_bytes!("assets/player1.pcx")),
-    );
-    sprites.insert(
-        "player2".into(),
-        load_pcx(include_bytes!("assets/player2.pcx")),
-    );
-    sprites.insert(
-        "shield".into(),
-        load_pcx(include_bytes!("assets/shield.pcx")),
-    );
-    // sprites.insert("laser1".into(), load_pcx(include_bytes!("assets/laser1.pcx")));
-    // sprites.insert("laser2".into(), load_pcx(include_bytes!("assets/laser2.pcx")));
+    sprites.insert(Blipjoy1, load_pcx(include_bytes!("assets/blipjoy1.pcx")));
+    sprites.insert(Blipjoy2, load_pcx(include_bytes!("assets/blipjoy2.pcx")));
+
+    sprites.insert(Ferris1, load_pcx(include_bytes!("assets/ferris1.pcx")));
+    sprites.insert(Ferris2, load_pcx(include_bytes!("assets/ferris2.pcx")));
+
+    sprites.insert(Cthulhu1, load_pcx(include_bytes!("assets/cthulhu1.pcx")));
+    sprites.insert(Cthulhu2, load_pcx(include_bytes!("assets/cthulhu2.pcx")));
+
+    sprites.insert(Player1, load_pcx(include_bytes!("assets/player1.pcx")));
+    sprites.insert(Player2, load_pcx(include_bytes!("assets/player2.pcx")));
+
+    sprites.insert(Shield1, load_pcx(include_bytes!("assets/shield.pcx")));
+
+    // sprites.insert(Laser1, load_pcx(include_bytes!("assets/laser1.pcx")));
+    // sprites.insert(Laser2, load_pcx(include_bytes!("assets/laser2.pcx")));
 
     Assets { sprites }
 }

simple-invaders/src/sprites.rs

@@ -6,13 +6,33 @@ use crate::{Point, SCREEN_WIDTH};
 // This is the type stored in the `Assets` hash map
 pub(crate) type CachedSprite = (usize, usize, Rc<Vec<u8>>);
 
+/// Frame identifier for managing animations.
+#[derive(Debug, Eq, Hash, PartialEq)]
+pub(crate) enum Frame {
+    Blipjoy1,
+    Blipjoy2,
+
+    Ferris1,
+    Ferris2,
+
+    Cthulhu1,
+    Cthulhu2,
+
+    Player1,
+    Player2,
+
+    Shield1,
+    // Laser1,
+    // Laser2,
+}
+
 /// Sprites can be drawn and animated.
 #[derive(Debug)]
 pub(crate) struct Sprite {
     width: usize,
     height: usize,
     pixels: Vec<u8>,
-    frame: String,
+    frame: Frame,
 }
 
 /// SpriteRefs can be drawn and animated.
@@ -23,30 +43,73 @@ pub(crate) struct SpriteRef {
     width: usize,
     height: usize,
     pixels: Rc<Vec<u8>>,
-    frame: String,
+    frame: Frame,
 }
 
-pub(crate) trait Sprites {
-    fn new(assets: &Assets, name: &str) -> Self;
+/// Drawables can be blitted to the pixel buffer and animated.
+pub(crate) trait Drawable {
     fn width(&self) -> usize;
     fn height(&self) -> usize;
     fn pixels(&self) -> &[u8];
     fn update_pixels(&mut self, pixels: Rc<Vec<u8>>);
-    fn frame(&self) -> &str;
-    fn update_frame(&mut self, frame: &str);
+    fn frame(&self) -> &Frame;
+    fn update_frame(&mut self, frame: Frame);
+
+    fn animate(&mut self, assets: &Assets) {
+        use Frame::*;
+
+        let assets = assets.sprites();
+        let (pixels, frame) = match self.frame() {
+            Blipjoy1 => (assets.get(&Blipjoy2).unwrap().2.clone(), Blipjoy2),
+            Blipjoy2 => (assets.get(&Blipjoy1).unwrap().2.clone(), Blipjoy1),
+
+            Ferris1 => (assets.get(&Ferris2).unwrap().2.clone(), Ferris2),
+            Ferris2 => (assets.get(&Ferris1).unwrap().2.clone(), Ferris1),
+
+            Cthulhu1 => (assets.get(&Cthulhu2).unwrap().2.clone(), Cthulhu2),
+            Cthulhu2 => (assets.get(&Cthulhu1).unwrap().2.clone(), Cthulhu1),
+
+            Player1 => (assets.get(&Player2).unwrap().2.clone(), Player2),
+            Player2 => (assets.get(&Player1).unwrap().2.clone(), Player1),
+
+            // This should not happen, but here we are!
+            Shield1 => (assets.get(&Shield1).unwrap().2.clone(), Shield1),
+            // Laser1 => (assets.get(&Laser2).unwrap().2.clone(), Laser2),
+            // Laser2 => (assets.get(&Laser1).unwrap().2.clone(), Laser1),
+        };
+
+        self.update_pixels(pixels);
+        self.update_frame(frame);
+    }
 }
 
-impl Sprites for Sprite {
-    fn new(assets: &Assets, name: &str) -> Sprite {
-        let cached_sprite = assets.sprites().get(name).unwrap();
-        Sprite {
-            width: cached_sprite.0,
-            height: cached_sprite.1,
-            pixels: cached_sprite.2.to_vec(),
-            frame: name.into(),
-        }
-    }
+impl Sprite {
+    pub(crate) fn new(assets: &Assets, frame: Frame) -> Sprite {
+        let (width, height, pixels) = assets.sprites().get(&frame).unwrap();
 
+        Sprite {
+            width: *width,
+            height: *height,
+            pixels: pixels.to_vec(),
+            frame,
+        }
+    }
+}
+
+impl SpriteRef {
+    pub(crate) fn new(assets: &Assets, frame: Frame) -> SpriteRef {
+        let (width, height, pixels) = assets.sprites().get(&frame).unwrap();
+
+        SpriteRef {
+            width: *width,
+            height: *height,
+            pixels: pixels.clone(),
+            frame,
+        }
+    }
+}
+
+impl Drawable for Sprite {
     fn width(&self) -> usize {
         self.width
     }
@@ -60,29 +123,19 @@ impl Sprites for Sprite {
     }
 
     fn update_pixels(&mut self, pixels: Rc<Vec<u8>>) {
-        self.pixels.copy_from_slice(&pixels);
+        self.pixels = pixels.to_vec();
     }
 
-    fn frame(&self) -> &str {
+    fn frame(&self) -> &Frame {
         &self.frame
     }
 
-    fn update_frame(&mut self, frame: &str) {
-        self.frame = frame.into();
+    fn update_frame(&mut self, frame: Frame) {
+        self.frame = frame;
     }
 }
 
-impl Sprites for SpriteRef {
-    fn new(assets: &Assets, name: &str) -> SpriteRef {
-        let cached_sprite = assets.sprites().get(name).unwrap();
-        SpriteRef {
-            width: cached_sprite.0,
-            height: cached_sprite.1,
-            pixels: cached_sprite.2.clone(),
-            frame: name.into(),
-        }
-    }
-
+impl Drawable for SpriteRef {
     fn width(&self) -> usize {
         self.width
     }
@@ -99,18 +152,19 @@ impl Sprites for SpriteRef {
         self.pixels = pixels;
     }
 
-    fn frame(&self) -> &str {
+    fn frame(&self) -> &Frame {
         &self.frame
     }
 
-    fn update_frame(&mut self, frame: &str) {
-        self.frame = frame.into();
+    fn update_frame(&mut self, frame: Frame) {
+        self.frame = frame;
     }
 }
 
+/// Blit a drawable to the pixel buffer.
 pub(crate) fn blit<S>(screen: &mut [u8], dest: &Point, sprite: &S)
 where
-    S: Sprites,
+    S: Drawable,
 {
     let pixels = sprite.pixels();
     let width = sprite.width() * 4;