move train stuff into folders

scenes/OrbitCamera.tscn

@@ -4,7 +4,9 @@
 
 [node name="OrbitCamera" type="Spatial"]
 script = ExtResource( 1 )
+_zoomSensitivity = 50.0
+_cameraPath = NodePath("Camera")
 
 [node name="Camera" type="Camera" parent="."]
-transform = Transform( 1, 0, 0, 0, 0.964146, 0.265371, 0, -0.265371, 0.964146, 0, 2.21115, 9.48434 )
+transform = Transform( 1, 0, 0, 0, 0.964146, 0.265371, 0, -0.265371, 0.964146, 0, 7.12726, 27.3456 )
 fov = 25.0

scripts/OrbitCamera.cs

@@ -4,7 +4,26 @@ using System;
 public class OrbitCamera : Spatial
 {
     [Export]
-    private float _sensitivity = 200f;
+    private float _lookSensitivity = 200f;
+    [Export]
+    private float _zoomSensitivity = 10f;
+    [Export]
+    private Vector2 _fovRange = new Vector2(10, 60);
+
+    [Export]
+    private NodePath _cameraPath;
+    private Camera _camera = null;
+    private Camera Camera
+    {
+        get
+        {
+            if (_camera == null)
+            {
+                _camera = GetNode<Camera>(_cameraPath);
+            }
+            return _camera;
+        }
+    }
 
     private Vector2 _rotation;
     private bool _canRotate = false;
@@ -24,7 +43,8 @@ public class OrbitCamera : Spatial
     public override void _Process(float delta)
     {
         Rotation = Vector3.Zero;
-        var sensitivity = -1f / _sensitivity;
+        var sensitivity = -1f / _lookSensitivity;
+
         Rotate(Vector3.Right, _rotation.y * sensitivity);
         Rotate(Vector3.Up, _rotation.x * sensitivity);
     }
@@ -32,9 +52,32 @@ public class OrbitCamera : Spatial
     // left click to drag
     private void HandleMouseButton(InputEventMouseButton mouseButton)
     {
-        if (mouseButton.ButtonIndex != (int)ButtonList.Left) return;
-
+        switch ((ButtonList)mouseButton.ButtonIndex)
+        {
+            case ButtonList.Left:
                 _canRotate = mouseButton.Pressed;
+                break;
+            case ButtonList.WheelUp:
+                Zoom(-1);
+                break;
+            case ButtonList.WheelDown:
+                Zoom(1);
+                break;
+        }
+    }
+
+    private void Zoom(int dir)
+    {
+        if (dir != 1 && dir != -1)
+            throw new ArgumentException();
+
+        var fov = Camera.Fov;
+        var zoom = _zoomSensitivity / Camera.Fov;
+
+        fov += (float)dir * zoom;
+        fov = Mathf.Clamp(fov, _fovRange.x, _fovRange.y);
+
+        Camera.Fov = fov;
     }
 
     private void HandleMouseMovement(InputEventMouseMotion mouseMotion)