1 files changed, 35 insertions, 21 deletions
diff --git a/examples/shapes.scm b/examples/shapes.scm
index abaf371..1c20219 100644
--- a/examples/shapes.scm
+++ b/examples/shapes.scm
@@ -15,7 +15,8 @@
 ;;; along with this program.  If not, see
 ;;; <http://www.gnu.org/licenses/>.
 
-(use-modules (sly game)
+(use-modules (srfi srfi-26)
+             (sly game)
              (sly window)
              (sly utils)
              (sly signal)
@@ -31,45 +32,58 @@
 
 (load "common.scm")
 
-(define crate-texture
-  (load-texture "images/crate.png"))
+(define-signal crate-texture
+  (on-start (load-texture "images/crate.png")))
 
-(define sky-background
-  (load-sprite "images/country-sky.png"))
+(define-signal sky-background
+  (on-start (load-sprite "images/country-sky.png")))
 
-(define forest-background
-  (load-sprite "images/country-trees.png"))
+(define-signal forest-background
+  (on-start (load-sprite "images/country-trees.png")))
 
-(define background
+(define (make-background sky forest)
   (scale 1/10
          (move (vector3 0 0 -10)
                (render-begin
-                (render-sprite sky-background)
-                (render-sprite forest-background)))))
+                (render-sprite sky)
+                (render-sprite forest)))))
 
-(define unit-cube
-  (make-cube 1 #:texture crate-texture))
+(define-signal background
+  (signal-map-maybe make-background
+                    sky-background
+                    forest-background))
 
-(define cubes
+(define-signal unit-cube
+  (signal-map-maybe (cut make-cube 1 #:texture <>)
+                    crate-texture))
+
+(define (make-cubes unit-cube)
   (move (vector3 0 0 -3)
         (render-begin
          (move (vector3 2 0 0) unit-cube)
          unit-cube
          (move (vector3 -2 0 0) unit-cube))))
 
+(define-signal cubes
+  (signal-map-maybe make-cubes unit-cube))
+
 (define camera
   (3d-camera #:area (make-rect 0 0 640 480)))
 
 (define-signal scene
   (signal-let ((rotation (signal-map (lambda (x) (/ x 48))
-                                     (signal-timer))))
-    (with-camera camera
-      (render-begin
-       background
-       ;; Spinnin' cubes!
-       (with-depth-test #t
-         (rotate-x (* rotation 2)
-                   (rotate-y rotation cubes)))))))
+                                     (signal-timer)))
+               (background background)
+               (cubes cubes))
+    (if (and background cubes)
+        (with-camera camera
+          (render-begin
+           background
+           ;; Spinnin' cubes!
+           (with-depth-test #t
+             (rotate-x (* rotation 2)
+                       (rotate-y rotation cubes)))))
+        render-nothing)))
 
 (with-window (make-window #:title "Shapes!")
   (run-game-loop scene))