diff options
Diffstat (limited to '2d')
| -rw-r--r-- | 2d/game-loop.scm | 29 |
1 files changed, 21 insertions, 8 deletions
diff --git a/2d/game-loop.scm b/2d/game-loop.scm index 4b097ce..f2faf13 100644 --- a/2d/game-loop.scm +++ b/2d/game-loop.scm @@ -31,6 +31,7 @@ run-game-loop)) (define target-fps 60) +(define frame-interval (/ 1000 target-fps)) ;;; ;;; Callbacks @@ -100,16 +101,28 @@ (set! last-time time) (set! fps 0)))))) +(define (update accumulator) + "Call the update callback. The update callback will be called as +many times as frame-interval can divide accumulator. The return value +is the unused accumulator time." + (if (>= accumulator frame-interval) + (begin + (update-callback) + (update (- accumulator frame-interval))) + accumulator)) + (define update-and-render - (let ((last-update 0) - (update-interval (/ 1000 target-fps))) + (let ((remainder 0) + (last-time 0)) (lambda () - "Calls update and draw callback when enough time has passed since -the last tick." - (let ((time (SDL:get-ticks))) - (when (>= time (+ last-update update-interval)) - (set! last-update time) - (update-callback) + "Calls update and draw callback when enough time has passed +since the last tick." + (let* ((time (SDL:get-ticks)) + (elapsed (- time last-time)) + (accumulator (+ remainder elapsed))) + (when (>= accumulator frame-interval) + (set! last-time time) + (set! remainder (update accumulator)) (accumulate-fps) (render)))))) |