From: Tomas Wenström <tomas.wenstrom@gmail.com>
Date: Sat, 9 Feb 2019 18:15:48 +0000 (+0100)
Subject: Use trait for boll variants
X-Git-Url: http://git.dolda2000.com/gitweb/?p=kaka%2Frust-sdl-test.git;a=commitdiff_plain;h=c315bb317cbd779063cb0135abe731886de30838

Use trait for boll variants
---

diff --git a/src/boll.rs b/src/boll.rs
index b273f1d..f936fca 100644
--- a/src/boll.rs
+++ b/src/boll.rs
@@ -7,13 +7,18 @@ use sdl2::video::Window;
 use {SCREEN_HEIGHT, SCREEN_WIDTH};
 use common::Point2D;
 
-pub struct Boll {
+pub trait Boll {
+    fn update(&mut self);
+    fn draw(&mut self, canvas: &mut Canvas<Window>, size: u32);
+}
+
+pub struct SquareBoll {
     pub pos: Point2D<f64>,
     pub vel: Point2D<f64>,
 }
 
-impl Boll {
-    pub fn update(&mut self) {
+impl Boll for SquareBoll {
+    fn update(&mut self) {
         self.vel.y += 0.1;
         self.pos += self.vel;
 
@@ -35,7 +40,7 @@ impl Boll {
         }
     }
 
-    pub fn draw(&mut self,canvas: &mut Canvas<Window>, size: u32) {
+    fn draw(&mut self, canvas: &mut Canvas<Window>, size: u32) {
         canvas.set_draw_color(Color::RGBA(
             255 - std::cmp::min(255, (self.vel.length() * 25.0) as u8),
             (255.0 * (self.pos.x / SCREEN_WIDTH as f64)) as u8,
diff --git a/src/main.rs b/src/main.rs
index 7182836..0cb2ecf 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -22,7 +22,7 @@ use sdl2::video::Window;
 use sdl2::video::WindowContext;
 use time::PreciseTime;
 
-use boll::Boll;
+use boll::{Boll, SquareBoll};
 use common::Point2D;
 
 #[macro_use] mod common;
@@ -33,6 +33,8 @@ const SCREEN_HEIGHT: u32 = (SCREEN_WIDTH as f64 * (1440.0 / 2560.0)) as u32;
 const FPS: u32 = 60;
 const NS_PER_FRAME: u32 = 1_000_000_000 / FPS;
 
+type Bollar = Vec<Box<dyn Boll>>;
+
 fn init() -> (Canvas<Window>, EventPump) {
     let context = sdl2::init().unwrap();
     let video = context.video().unwrap();
@@ -66,7 +68,7 @@ fn main() {
     let mut frame_count: u64 = 0;
     let mut fps_time = PreciseTime::now();
 
-    let mut bolls: Vec<Boll> = Vec::new();
+    let mut bolls: Bollar = Bollar::new();
     let mut boll_size = 1;
 
     let texture_creator = canvas.texture_creator();
@@ -123,10 +125,10 @@ fn main() {
                 }
                 Event::KeyDown { keycode: Some(Keycode::KpPlus), .. } => { boll_size = std::cmp::min(boll_size + 1, 32) }
                 Event::KeyDown { keycode: Some(Keycode::KpMinus), .. } => { boll_size = std::cmp::max(boll_size - 1, 1) }
-                Event::MouseMotion { x, y, .. } => { bolls.push(Boll {
+                Event::MouseMotion { x, y, .. } => { bolls.push(Box::new(SquareBoll {
                     pos: point!(x as f64, y as f64),
                     vel: point!(0.0, 0.0),
-                }) }
+                })) }
                 _ => {}
             }
         }
@@ -150,7 +152,7 @@ fn main() {
     println!("number of bolls: {}", bolls.len());
 }
 
-fn change_boll_count(mut bolls: &mut Vec<Boll>, delta: i32) {
+fn change_boll_count(mut bolls: &mut Bollar, delta: i32) {
     if delta > 0 {
         for _i in 0..delta {
             add_boll(&mut bolls);
@@ -162,10 +164,10 @@ fn change_boll_count(mut bolls: &mut Vec<Boll>, delta: i32) {
     }
 }
 
-fn add_boll(bolls: &mut Vec<Boll>) {
+fn add_boll(bolls: &mut Bollar) {
     let mut rng = rand::thread_rng();
-    bolls.push(Boll {
+    bolls.push(Box::new(SquareBoll {
         pos: point!(rng.gen_range(0, SCREEN_WIDTH) as f64, rng.gen_range(0, SCREEN_HEIGHT) as f64),
         vel: point!(rng.gen_range(-2.0, 2.0), rng.gen_range(-2.0, 2.0)),
-    });
+    }));
 }