Unnecessary mutability

diff --git a/src/boll.rs b/src/boll.rs
index 35dd97e..64be265 100644 (file)
--- a/src/boll.rs
+++ b/src/boll.rs
@@ -10,7 +10,7 @@ use sdl2::gfx::primitives::DrawRenderer;
 
 pub trait Boll {
     fn update(&mut self);
-    fn draw(&mut self, canvas: &mut Canvas<Window>, size: u32);
+    fn draw(&self, canvas: &mut Canvas<Window>, size: u32);
 }
 
 pub struct SquareBoll {
@@ -41,7 +41,7 @@ impl Boll for SquareBoll {
         }
     }
 
-    fn draw(&mut self, canvas: &mut Canvas<Window>, size: u32) {
+    fn draw(&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,
@@ -74,7 +74,7 @@ impl Boll for CircleBoll {
         self.boll.update();
     }
 
-    fn draw(&mut self, canvas: &mut Canvas<Window>, size: u32) {
+    fn draw(&self, canvas: &mut Canvas<Window>, size: u32) {
         let val = 255 - std::cmp::min(255, (self.boll.vel.length() * 20.0) as u8);
         canvas.filled_circle(self.boll.pos.x as i16, self.boll.pos.y as i16, size as i16, Color::RGBA(
             val,