diff options
| -rw-r--r-- | 2d/game.scm | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/2d/game.scm b/2d/game.scm index d8eeb9b..ac33881 100644 --- a/2d/game.scm +++ b/2d/game.scm @@ -30,6 +30,7 @@ #:use-module (2d signal) #:use-module (2d window) #:export (tick-interval + max-ticks-per-frame game-agenda draw-hook start-game-loop @@ -41,6 +42,11 @@ ;; Update 60 times per second by default. (define tick-interval (floor (/ 1000 60))) +;; The maximum number of times the game loop will update game state in +;; a single frame. When this upper bound is reached due to poor +;; performance, the game will start to slow down instead of becoming +;; completely unresponsive and possibly crashing. +(define max-ticks-per-frame 4) (define draw-hook (make-hook 2)) (define game-agenda (make-agenda)) @@ -57,11 +63,15 @@ "Call the update callback. The update callback will be called as many times as tick-interval can divide LAG. The return value is the unused accumulator time." - (if (>= lag tick-interval) - (begin - (tick-agenda! game-agenda) - (update (- lag tick-interval))) - lag)) + (define (iter ticks) + (cond ((>= ticks max-ticks-per-frame) + lag) + ((>= lag tick-interval) + (tick-agenda! game-agenda) + (update (- lag tick-interval))) + (else + lag))) + (iter 0)) (define (alpha lag) "Calculate interpolation factor in the range [0, 1] for the |