transition: Add sequence scene.

* starling/transition.scm (<sequence-scene>): New class.

1 files changed, 30 insertions, 1 deletions

diff --git a/starling/transition.scm b/starling/transition.scm
index 0d70e2f..f673d9c 100644
--- a/starling/transition.scm
+++ b/starling/transition.scm
@@ -24,18 +24,47 @@
   #:use-module (chickadee math rect)
   #:use-module (chickadee render color)
   #:use-module (chickadee scripting)
+  #:use-module (ice-9 match)
   #:use-module (oop goops)
   #:use-module (starling kernel)
   #:use-module (starling node)
   #:use-module (starling node-2d)
   #:use-module (starling scene)
-  #:export (<transition>
+  #:export (<sequence-scene>
+            scenes
+
+            <transition>
             scene-from
             scene-to
             duration
 
             <fade-transition>))
 
+
+;;;
+;;; Sequence
+;;;
+
+;; Not a transition like all the others, but still a form of
+;; transitioning scenes.
+
+(define-class <sequence-scene> (<scene>)
+  (scenes #:accessor scenes #:init-keyword #:scenes))
+
+(define-method (on-enter (sequence <sequence-scene>))
+  (match (scenes sequence)
+    ((scene)
+     ;; If we've reached the last scene, we're done!
+     (replace-scene scene))
+    ((scene . rest)
+     (set! (scenes sequence) rest)
+     (push-scene scene))))
+
+
+;;;
+;;; Transitions
+;;;
+
 (define-class <transition> (<scene>)
   (scene-from #:getter scene-from #:init-keyword #:from)
   (scene-to #:getter scene-to #:init-keyword #:to)