moved camera to a separate mod and use Rect intersection and has_intersection methods

src/camera.rs

@@ -0,0 +1,24 @@
+use sdl2::rect::Rect;
+
+
+pub struct Camera {
+    pub x: i32,
+    pub y: i32,
+    pub w: i32,
+    pub h: i32
+}
+
+impl Camera {
+    pub fn new(x: i32, y: i32, w: i32, h: i32) -> Camera {
+        Camera {
+            x: x,
+            y: y,
+            w: w,
+            h: h
+        }
+    }
+
+    pub fn get_rect(&self) -> Rect {
+        Rect::new(self.x, self.y, self.w, self.h)
+    }
+}