34cf4058 |
1 | /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * |
2 | * Copyright (C) 2011 yongzh (freeman.yong@gmail.com) * |
3 | * * |
4 | * This program is free software; you can redistribute it and/or modify * |
5 | * it under the terms of the GNU General Public License as published by * |
6 | * the Free Software Foundation; either version 2 of the License, or * |
7 | * (at your option) any later version. * |
8 | * * |
9 | * This program is distributed in the hope that it will be useful, * |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of * |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * |
12 | * GNU General Public License for more details. * |
13 | * * |
14 | * You should have received a copy of the GNU General Public License * |
15 | * along with this program; if not, write to the * |
16 | * Free Software Foundation, Inc., * |
17 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. * |
18 | * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ |
19 | |
20 | #include "FrameSkipper.h" |
21 | #include "ticks.h" |
22 | |
23 | FrameSkipper::FrameSkipper() |
24 | : skipType(AUTO), maxSkips(2), targetFPS(60) |
25 | { |
26 | } |
27 | |
28 | void FrameSkipper::start() |
29 | { |
30 | initialTicks = 0; |
31 | virtualCount = 0; |
32 | skipCounter = 0; |
33 | } |
34 | |
35 | void FrameSkipper::update() |
36 | { |
37 | // for the first frame |
38 | if (initialTicks == 0) { |
39 | initialTicks = ticksGetTicks(); |
40 | return; |
41 | } |
42 | |
43 | unsigned int elapsed = ticksGetTicks() - initialTicks; |
44 | unsigned int realCount = elapsed * targetFPS / 1000; |
45 | |
46 | virtualCount++; |
47 | if (realCount >= virtualCount) { |
48 | if (realCount > virtualCount && |
49 | skipType == AUTO && skipCounter < maxSkips) { |
50 | skipCounter++; |
51 | } else { |
52 | virtualCount = realCount; |
53 | if (skipType == AUTO) |
54 | skipCounter = 0; |
55 | } |
56 | } |
57 | if (skipType == MANUAL) { |
58 | if (++skipCounter > maxSkips) |
59 | skipCounter = 0; |
60 | } |
61 | } |