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| author | David Thompson <dthompson2@worcester.edu> | 2018-08-30 08:12:28 -0400 |
|---|---|---|
| committer | David Thompson <dthompson2@worcester.edu> | 2018-08-30 08:13:12 -0400 |
| commit | 9b5bec99454995b40713e8af03b5853a609f2f25 (patch) | |
| tree | 34e925628bb2e6b76c2ba2650842bc02a7f56c2e | |
| parent | a5e0a9378daaee6a04ce8e2298e9d87137ee6048 (diff) | |
kernel: Add previous-scene procedure.
* starling/kernel.scm (previous-scene): New procedure.
| -rw-r--r-- | starling/kernel.scm | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/starling/kernel.scm b/starling/kernel.scm index 25e92b6..078b6df 100644 --- a/starling/kernel.scm +++ b/starling/kernel.scm @@ -58,6 +58,7 @@ elapsed-time fps current-scene + previous-scene push-scene pop-scene replace-scene) @@ -282,10 +283,16 @@ (deactivate kernel) (close-window! (window kernel)))))) -(define-method (current-scene) +(define (current-scene) "Return the currently active scene" - (and (not (null? (scenes (current-kernel)))) - (car (scenes (current-kernel))))) + (match (scenes (current-kernel)) + (() #f) + ((scene . rest) scene))) + +(define (previous-scene) + (match (scenes (current-kernel)) + ((or () (_)) #f) + ((_ scene . rest) scene))) (define-method (push-scene (scene <scene>)) "Make SCENE the currently active scene and remember the previously |