anchovy.gui.application.fpshelper source code

1 /*
2 Copyright (c) 2013 Andrey Penechko
3 
4 Boost Software License - Version 1.0 - August 17th, 2003
5 
6 Permission is hereby granted, free of charge, to any person or organization
7 obtaining a copy of the software and accompanying documentation covered by
8 this license the "Software" to use, reproduce, display, distribute,
9 execute, and transmit the Software, and to prepare derivative works of the
10 Software, and to permit third-parties to whom the Software is furnished to
11 do so, all subject to the following:
12 
13 The copyright notices in the Software and this entire statement, including
14 the above license grant, this restriction and the following disclaimer,
15 must be included in all copies of the Software, in whole or in part, and
16 all derivative works of the Software, unless such copies or derivative
17 works are solely in the form of machine-executable object code generated by
18 a source language processor.
19 
20 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
21 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
22 FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
23 SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
24 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
25 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
26 DEALINGS IN THE SOFTWARE.
27 */
28 
29 module anchovy.gui.application.fpshelper;
30 
31 import core.thread;
32 import anchovy.utils.signal;
33 
34 /++
35  + Helper for measuring frames per second and setting static FPS.
36  + Usually needs to be located as field of game class.
37  +/
38 struct FpsHelper
39 {
40 	Signal!(FpsHelper*) fpsUpdated;
41 
42 	/// fps will be updated each updateInterval seconds
43 	float updateInterval = 0.5;
44 
45 	/// Stores actual FPS value
46 	float fps = 0;
47 
48 	/// Stores last delta time passed into update()
49 	float deltaTime;
50 
51 	/// Stores amount of updates between 
52 	size_t fpsTicks;
53 
54 	/// Accumulates time before reaching update interval
55 	float secondsAccumulator = 0;
56 
57 	bool limitFps = true;
58 
59 	uint maxFps = 60;
60 
61 	/// Delta time value will clamped to meet interval [0;timeLimit].
62 	/// This can prevent from value lags when entering hibernation or resizing the window.
63 	float timeLimit = 1;
64 
65 	void update(float dt)
66 	{
67 		if (dt > timeLimit)
68 		{
69 			dt = timeLimit;
70 		}
71 		deltaTime = dt;
72 
73 		++fpsTicks;
74 		secondsAccumulator += dt;
75 
76 		if (secondsAccumulator >= updateInterval)
77 		{
78 			fps = fpsTicks/secondsAccumulator;
79 			secondsAccumulator -= updateInterval;
80 			fpsTicks = 0;
81 			fpsUpdated.emit(&this);
82 		}
83 	}
84 
85 	void sleepAfterFrame(float frameTime)
86 	{
87 		if (limitFps)
88 		{
89 			uint msecs = cast(uint)((1/cast(float)maxFps - frameTime)*1000);
90 			Thread.sleep(dur!"msecs"(msecs>2? msecs - 1: msecs));
91 		}
92 	}
93 }
94