Add keyboard input for camera movement

src/input.rs

@@ -0,0 +1,33 @@
+use fnv::FnvHashSet;
+use sfml::window::{Event, Key};
+
+#[derive(Default)]
+pub struct KbInput {
+    down: FnvHashSet<Key>,
+    pressed: FnvHashSet<Key>,
+}
+
+impl KbInput {
+    pub fn update_from_event(&mut self, ev: &Event) {
+        match ev {
+            Event::KeyPressed { code, .. } => {
+                self.pressed.insert(*code);
+                self.down.insert(*code);
+            }
+            Event::KeyReleased { code, .. } => {
+                self.down.remove(code);
+            }
+            _ => {}
+        }
+    }
+    /// Pressed event should be cleared every frame
+    pub fn clear_pressed(&mut self) {
+        self.pressed.clear();
+    }
+    pub fn down(&self, key: Key) -> bool {
+        self.down.contains(&key)
+    }
+    pub fn pressed(&self, key: Key) -> bool {
+        self.pressed.contains(&key)
+    }
+}