Add panning with rmb

src/main.rs

@@ -11,6 +11,7 @@ use sdl2::keyboard::Keycode;
 use sdl2::pixels::Color;
 use sdl2::render::WindowCanvas;
 use sdl2::image::INIT_PNG;
+use sdl2::mouse::MouseButton;
 
 use perlin_noise::PerlinNoise;
 
@@ -22,11 +23,16 @@ struct GameState {
     camera_x: i32,
     camera_y: i32,
 
+    camera_panning: bool,
+}
+
 impl GameState {
     fn new() -> Self {
         Self {
             camera_x: 0,
             camera_y: 0,
+
+            camera_panning: false,
         }
     }
 }
@@ -58,6 +64,19 @@ fn update(event_pump: &mut EventPump, game_state: &mut GameState) -> bool {
                 };
             },
 
+            Event::MouseButtonDown { mouse_btn: MouseButton::Right, .. } => {
+                game_state.camera_panning = true;
+            },
+            Event::MouseButtonUp { mouse_btn: MouseButton::Right, .. } => {
+                game_state.camera_panning = false;
+            },
+            Event::MouseMotion { xrel: x, yrel: y, .. } => {
+                if game_state.camera_panning {
+                    game_state.camera_x -= x;
+                    game_state.camera_y -= y;
+                }
+            }
+
             _ => {},
         };
     }