Prepare to flip player.

src/player.rs

@@ -1,5 +1,9 @@
 use sdl2::rect::Rect;
 
+pub enum PlayerFacing {
+    Left,
+    Right
+}
 
 pub struct Player {
     pub x: f32,
@@ -9,7 +13,8 @@ pub struct Player {
     pub dx: f32,
     pub dy: f32,
     pub gravity: f32,
-    pub on_ground: bool
+    pub on_ground: bool,
+    pub facing: PlayerFacing
 }
 
 impl Player {
@@ -22,11 +27,25 @@ impl Player {
             dx: 0.0,
             dy: 0.0,
             gravity: 0.3,
-            on_ground: false
+            on_ground: false,
+            facing: PlayerFacing::Right
         }
     }
 
     pub fn update(&mut self) {
+        match self.facing {
+            PlayerFacing::Right => {
+                if self.dx < 0.0 {
+                    self.facing = PlayerFacing::Left;
+                }
+            },
+            PlayerFacing::Left => {
+                if self.dx > 0.0 {
+                    self.facing = PlayerFacing::Right;
+                }
+            }
+        }
+
         self.dy += self.gravity;
 
         if self.dy > 8.0 {