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15 # Frame-rate control for applications
19 private import realtime
22 # Limit the frame-rate to a given frequency
24 # This basically limits how much `frame_core` is called per second.
25 # Zero (or a negative value) means no limit.
27 # Applications can modify this value even during the main-loop.
28 var maximum_fps
= 60.0 is writable
32 # Updated each 5 seconds, initialized at the value of `maximum_fps`.
33 var current_fps
: Float = maximum_fps
is lazy
41 # The clock for limit_fps
42 private var clock
= new Clock
44 # Number of frames since the last deadline
46 # Used to compute `current_fps`.
47 private var frame_count
= 0
49 # Deadline used to compute `current_fps`
50 private var frame_count_deadline
= 5.0
52 # Check and sleep to maintain a frame-rate bellow `maximum_fps`
54 # Also periodically update `current_fps`
55 # Is automatically called at the end of `full_frame`.
59 if t
>= frame_count_deadline
then
60 var cfps
= frame_count
.to_f
/ 5.0
61 self.current_fps
= cfps
63 frame_count_deadline
= t
+ 5.0
67 var mfps
= maximum_fps
68 if mfps
<= 0.0 then return
69 var lapse
= clock
.lapse
71 var target_dt
= 1.0 / mfps
72 if dt
< target_dt
then
73 var sleep_t
= target_dt
- dt