From feac27c6b6b76871e91d0d57c85034f787990b37 Mon Sep 17 00:00:00 2001
From: "Timothy J. Warren" <tim@timshomepage.net>
Date: Fri, 24 Jul 2020 18:56:48 -0400
Subject: [PATCH] Finished 3.2 Animations

---
 src/components.rs               | 32 +++++++++++++++++++++-
 src/entities.rs                 | 47 +++++++++++++++++++++++++--------
 src/main.rs                     | 10 +++++--
 src/resources.rs                |  7 +++++
 src/systems/rendering_system.rs | 32 +++++++++++++++++++---
 5 files changed, 110 insertions(+), 18 deletions(-)

diff --git a/src/components.rs b/src/components.rs
index 395bc30..e48a6dc 100644
--- a/src/components.rs
+++ b/src/components.rs
@@ -19,6 +19,11 @@ impl Display for BoxColor {
     }
 }
 
+pub enum RenderableKind {
+    Static,
+    Animated,
+}
+
 #[derive(Debug, Component, Clone, Copy)]
 #[storage(VecStorage)]
 pub struct Position {
@@ -40,7 +45,32 @@ impl Position {
 #[derive(Component)]
 #[storage(VecStorage)]
 pub struct Renderable {
-    pub path: String,
+    paths: Vec<String>,
+}
+
+impl Renderable {
+    pub fn new_static(path: String) -> Self {
+        Self { paths: vec![path] }
+    }
+
+    pub fn new_animated(paths: Vec<String>) -> Self {
+        Self { paths }
+    }
+
+    pub fn kind(&self) -> RenderableKind {
+        match self.paths.len() {
+            0 => panic!("invalid renderable"),
+            1 => RenderableKind::Static,
+            _ => RenderableKind::Animated,
+        }
+    }
+
+    pub fn path(&self, path_index: usize) -> String {
+        // If we get asked for a path that is larger than the
+        // number of paths we actually have, we simply mod the index
+        // with the length to get an index that is in range
+        self.paths[path_index % self.paths.len()].clone()
+    }
 }
 
 #[derive(Component)]
diff --git a/src/entities.rs b/src/entities.rs
index d85ff85..550a917 100644
--- a/src/entities.rs
+++ b/src/entities.rs
@@ -2,34 +2,54 @@ use crate::components::*;
 use specs::{Builder, EntityBuilder, World, WorldExt};
 
 /// Cut down on the common syntax boilerplate
-fn common_entity<'w>(
+fn static_entity<'w>(
     world: &'w mut World,
     position: Position,
     z: u8,
     sprite_path: &str,
 ) -> EntityBuilder<'w> {
-    return world
+    let sprite_path = sprite_path.to_string();
+    world
         .create_entity()
         .with(position.with_z(z))
-        .with(Renderable {
-            path: sprite_path.to_string(),
-        });
+        .with(Renderable::new_static(sprite_path))
+}
+
+/// Cut down on animated entity boilerplate,
+/// and accept vectors of `&str` and `String`
+fn animated_entity<S>(
+    world: &mut World,
+    position: Position,
+    z: u8,
+    sprites: Vec<S>,
+) -> EntityBuilder
+where
+    S: Into<String>,
+{
+    let sprites: Vec<String> = sprites.into_iter().map(|s| s.into()).collect();
+    world
+        .create_entity()
+        .with(position.with_z(z))
+        .with(Renderable::new_animated(sprites))
 }
 
 pub fn create_wall(world: &mut World, position: Position) {
-    common_entity(world, position, 10, "/images/wall.png")
+    static_entity(world, position, 10, "/images/wall.png")
         .with(Wall {})
         .with(Immovable)
         .build();
 }
 
 pub fn create_floor(world: &mut World, position: Position) {
-    common_entity(world, position, 5, "/images/floor.png").build();
+    static_entity(world, position, 5, "/images/floor.png").build();
 }
 
 pub fn create_box(world: &mut World, position: Position, color: BoxColor) {
-    let path = format!("/images/box_{}.png", color);
-    common_entity(world, position, 10, &path)
+    let mut sprites: Vec<String> = vec![];
+    for x in 1..=2 {
+        sprites.push(format!("/images/box_{}_{}.png", color, x));
+    }
+    animated_entity(world, position, 10, sprites)
         .with(Box { color })
         .with(Movable)
         .build();
@@ -37,13 +57,18 @@ pub fn create_box(world: &mut World, position: Position, color: BoxColor) {
 
 pub fn create_box_spot(world: &mut World, position: Position, color: BoxColor) {
     let path = format!("/images/box_spot_{}.png", color);
-    common_entity(world, position, 9, &path)
+    static_entity(world, position, 9, &path)
         .with(BoxSpot { color })
         .build();
 }
 
 pub fn create_player(world: &mut World, position: Position) {
-    common_entity(world, position, 10, "/images/player.png")
+    let sprites = vec![
+        "/images/player_1.png",
+        "/images/player_2.png",
+        "/images/player_3.png",
+    ];
+    animated_entity(world, position, 10, sprites)
         .with(Player {})
         .with(Movable)
         .build();
diff --git a/src/main.rs b/src/main.rs
index defa079..4eedd07 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,7 +1,7 @@
 use ggez;
 use ggez::event::KeyCode;
 use ggez::event::KeyMods;
-use ggez::{conf, event, Context, GameResult};
+use ggez::{conf, event, timer, Context, GameResult};
 use specs::{RunNow, World, WorldExt};
 use std::path;
 
@@ -23,7 +23,7 @@ struct Game {
 }
 
 impl event::EventHandler for Game {
-    fn update(&mut self, _context: &mut Context) -> GameResult {
+    fn update(&mut self, context: &mut Context) -> GameResult {
         // Run input system
         {
             let mut is = InputSystem {};
@@ -36,6 +36,12 @@ impl event::EventHandler for Game {
             gss.run_now(&self.world);
         }
 
+        // Get an update time resource
+        {
+            let mut time = self.world.write_resource::<Time>();
+            time.delta += timer::delta(context);
+        }
+
         Ok(())
     }
 
diff --git a/src/resources.rs b/src/resources.rs
index 7ed7618..d057064 100644
--- a/src/resources.rs
+++ b/src/resources.rs
@@ -2,6 +2,7 @@ use ggez::event::KeyCode;
 use specs::World;
 use std::fmt;
 use std::fmt::Display;
+use std::time::Duration;
 
 #[derive(Default)]
 pub struct InputQueue {
@@ -14,6 +15,11 @@ pub struct Gameplay {
     pub moves_count: usize,
 }
 
+#[derive(Default)]
+pub struct Time {
+    pub delta: Duration,
+}
+
 pub enum GameplayState {
     Playing,
     Won,
@@ -39,4 +45,5 @@ impl Display for GameplayState {
 pub fn register_resources(world: &mut World) {
     world.insert(InputQueue::default());
     world.insert(Gameplay::default());
+    world.insert(Time::default());
 }
diff --git a/src/systems/rendering_system.rs b/src/systems/rendering_system.rs
index 6ca8fc5..f3fba17 100644
--- a/src/systems/rendering_system.rs
+++ b/src/systems/rendering_system.rs
@@ -4,9 +4,11 @@ use ggez::nalgebra as na;
 use ggez::{graphics, Context};
 use specs::{Join, Read, ReadStorage, System};
 
-use crate::components::{Position, Renderable};
+use std::time::Duration;
+
+use crate::components::*;
 use crate::constants::TILE_WIDTH;
-use crate::resources::Gameplay;
+use crate::resources::*;
 
 pub struct RenderingSystem<'a> {
     pub context: &'a mut Context,
@@ -28,17 +30,39 @@ impl RenderingSystem<'_> {
         )
         .expect("expected drawing queued text");
     }
+
+    pub fn get_image(&mut self, renderable: &Renderable, delta: Duration) -> Image {
+        let path_index = match renderable.kind() {
+            RenderableKind::Static => {
+                // We only have one image, so we just return that
+                0
+            }
+            RenderableKind::Animated => {
+                // If we have multiple, we want to select the right one based on the delta time.
+                // First we get the delta in milliseconds, we % by 1000 to get the seconds only
+                // and finally we divide by 250 to get a number between 0 and 4. If it's 4
+                // we technically are on the next iteration of the loop (or on 0), but we will let
+                // the renderable handle this logic of wrapping frames.
+                ((delta.as_millis() % 1000) / 250) as usize
+            }
+        };
+
+        let image_path = renderable.path(path_index);
+
+        Image::new(self.context, image_path).expect("expected image")
+    }
 }
 
 impl<'a> System<'a> for RenderingSystem<'a> {
     type SystemData = (
         Read<'a, Gameplay>,
+        Read<'a, Time>,
         ReadStorage<'a, Position>,
         ReadStorage<'a, Renderable>,
     );
 
     fn run(&mut self, data: Self::SystemData) {
-        let (gameplay, positions, renderables) = data;
+        let (gameplay, time, positions, renderables) = data;
 
         // Clear the screen/set the background
         graphics::clear(self.context, graphics::Color::new(0.95, 0.95, 0.95, 1.0));
@@ -52,7 +76,7 @@ impl<'a> System<'a> for RenderingSystem<'a> {
         // and draw it at the specified position.
         for (position, renderable) in rendering_data.iter() {
             // Load the image
-            let image = Image::new(self.context, renderable.path.clone()).expect("expected image");
+            let image = self.get_image(renderable, time.delta);
             let x = position.x as f32 * TILE_WIDTH;
             let y = position.y as f32 * TILE_WIDTH;