Refactor to be functional

1 files changed, 14 insertions, 11 deletions

diff --git a/engine.scm b/engine.scm
index 1d2c14f..e3a1fb0 100644
--- a/engine.scm
+++ b/engine.scm
@@ -133,16 +133,18 @@
     (values (or (and state (state-hook state #:update)) (game-update-hook game))
             (or (and state (state-hook state #:render)) (game-render-hook game)))))
 
-(define (update-camera-follow! game)
-  (when (game-scene game)
-    (let ((target-tag (scene-camera-target (game-scene game))))
-      (when target-tag
-        (let ((target (scene-find-tagged (game-scene game) target-tag)))
-          (when target
-            (camera-follow! (scene-camera (game-scene game))
-                            target
-                            (game-width game)
-                            (game-height game))))))))
+(define (update-camera-follow scene game)
+  (let ((target-tag (and scene (scene-camera-target scene))))
+    (if (not target-tag)
+        scene
+        (let ((target (scene-find-tagged scene target-tag)))
+          (if (not target)
+              scene
+              (update-scene scene
+                camera: (camera-follow (scene-camera scene)
+                                       target
+                                       (game-width game)
+                                       (game-height game))))))))
 
 (define (game-render! game render-fn)
   (renderer-set-clear-color! (game-renderer game) (game-scene game))
@@ -192,7 +194,8 @@
       (unless (input-held? input 'quit)
         (receive (update-fn render-fn) (resolve-hooks game)
           (when update-fn (update-fn game dt))
-          (update-camera-follow! game)
+          (when (game-scene game)
+            (game-scene-set! game (update-camera-follow (game-scene game) game)))
           (game-render! game render-fn))
         (sdl2:delay! (game-frame-delay game))
         (loop now))))