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15 # Frame-rate control for applications
19 private import realtime
22 # Limit the frame-rate to a given frequency
23 # This basically limits how much `frame_core` is called per second.
24 # Zero (or a negative value) means no limit.
26 # Applications can modify this value even during the main-loop.
27 var maximum_fps
= 60 is writable
30 # Updated each 5 seconds.
39 # The clock for limit_fps
40 private var clock
= new Clock
42 # Number of frames since the last deadline
43 # Used tocompute `current_fps`.
44 private var frame_count
= 0
46 # Deadline used to compute `current_fps`
47 private var frame_count_deadline
= 0
49 # Check and sleep to maitain a frame-rate bellow `maximum_fps`
50 # Also periodically uptate `current_fps`
51 # Is automatically called at the end of `full_frame`.
54 var t
= clock
.total
.sec
55 if t
>= frame_count_deadline
then
56 var cfps
= frame_count_deadline
.to_f
/ 5.0
57 self.current_fps
= cfps
59 frame_count_deadline
= t
+ 5
63 var mfps
= maximum_fps
64 if mfps
<= 0 then return
66 var target_dt
= 1000000000 / mfps
68 var nanosec
= dt
.nanosec
69 if sec
== 0 and nanosec
< target_dt
then
70 var sleep_t
= target_dt
- nanosec
71 sys
.nanosleep
(0, sleep_t
)