diff options
| -rw-r--r-- | 2d/game-loop.scm | 71 |
1 files changed, 37 insertions, 34 deletions
diff --git a/2d/game-loop.scm b/2d/game-loop.scm index 660a196..5860785 100644 --- a/2d/game-loop.scm +++ b/2d/game-loop.scm @@ -151,43 +151,26 @@ (render-callback) (SDL:gl-swap-buffers)) -(define accumulate-fps - (let ((last-time (delay (SDL:get-ticks))) - (fps 0)) - (lambda () - "Calculates frames per second." - (let ((time (SDL:get-ticks))) - (set! fps (1+ fps)) - (when (>= time (+ (force last-time) 1000)) - (pk 'FPS fps) - (set! last-time (delay time)) - (set! fps 0)))))) +(define (increment-fps fps fps-time) + "Increment frames-per-second counter. Resets to 0 when the +difference between time and fps-time is greater than or equal to one +second." + (if (>= fps-time 1000) + (begin + (pk 'FPS fps) + 0) + (1+ fps))) (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-agenda) - (update (- accumulator frame-interval))) - accumulator)) - -(define update-and-render - (let ((remainder 0) - (last-time (delay (SDL:get-ticks)))) - (lambda () - "Calls update and draw callback when enough time has passed -since the last tick." - (let* ((time (SDL:get-ticks)) - (elapsed (- time (force last-time))) - (accumulator (+ remainder elapsed))) - (when (>= accumulator frame-interval) - (set! last-time (delay time)) - (set! remainder (update accumulator)) - (accumulate-fps) - (render)))))) + (begin + (update-callback) + (update-agenda) + (update (- accumulator frame-interval))) + accumulator)) ;;; ;;; Game Loop @@ -195,6 +178,26 @@ since the last tick." (define (run-game-loop) "Runs event handling, update, and render loop." - (handle-events) - (update-and-render) - (run-game-loop)) + (define (game-loop time last-time fps-time accumulator fps) + (handle-events) + (let* ((dt (- time last-time)) + (accumulator (+ accumulator dt)) + (current-fps-time (+ fps-time dt)) + (current-time (SDL:get-ticks))) + ;; Update and render when the accumulator reaches the threshold. + (if (>= accumulator frame-interval) + (let ((remainder (update accumulator))) + (render) + (game-loop current-time + time + (modulo current-fps-time 1000) + remainder + (increment-fps fps current-fps-time))) + (game-loop current-time + time + current-fps-time + accumulator + fps)))) + + (let ((time (SDL:get-ticks))) + (game-loop time time 0 0 0))) |