Add elapsed-time procedure.

1 files changed, 6 insertions, 0 deletions

diff --git a/chickadee.scm b/chickadee.scm
index 10085ae..e2d8624 100644
--- a/chickadee.scm
+++ b/chickadee.scm
@@ -63,6 +63,7 @@
             set-window-size!
             set-window-position!
             set-window-fullscreen!
+            elapsed-time
             controller-button-pressed?
             controller-button-released?
             controller-axis
@@ -76,6 +77,11 @@
             run-game)
   #:re-export (abort-game))
 
+(define (elapsed-time)
+  "Return the number of milliseconds that have passed since the game
+loop was started."
+  (sdl-ticks))
+
 (define (key-pressed? key)
   "Return #t if KEY is currently being pressed."
   (sdl2:key-pressed? key))