summaryrefslogtreecommitdiff
path: root/src/video/video_driver.cpp
blob: 2f8efc4ad4773f50abb21f408c03df246bc5e173 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/** @file video_driver.cpp Common code between video driver implementations. */

#include "../stdafx.h"
#include "../core/random_func.hpp"
#include "../network/network.h"
#include "../blitter/factory.hpp"
#include "../debug.h"
#include "../fontcache.h"
#include "../gfx_func.h"
#include "../gfxinit.h"
#include "../progress.h"
#include "../thread.h"
#include "../window_func.h"
#include "video_driver.hpp"

bool _video_hw_accel; ///< Whether to consider hardware accelerated video drivers.
bool _video_vsync; ///< Whether we should use vsync (only if _video_hw_accel is enabled).

void VideoDriver::GameLoop()
{
	this->next_game_tick += this->GetGameInterval();

	/* Avoid next_game_tick getting behind more and more if it cannot keep up. */
	auto now = std::chrono::steady_clock::now();
	if (this->next_game_tick < now - ALLOWED_DRIFT * this->GetGameInterval()) this->next_game_tick = now;

	{
		std::lock_guard<std::mutex> lock(this->game_state_mutex);

		::GameLoop();
	}
}

void VideoDriver::GameThread()
{
	while (!_exit_game) {
		this->GameLoop();

		auto now = std::chrono::steady_clock::now();
		if (this->next_game_tick > now) {
			std::this_thread::sleep_for(this->next_game_tick - now);
		} else {
			/* Ensure we yield this thread if drawings wants to take a lock on
			 * the game state. This is mainly because most OSes have an
			 * optimization that if you unlock/lock a mutex in the same thread
			 * quickly, it will never context switch even if there is another
			 * thread waiting to take the lock on the same mutex. */
			std::lock_guard<std::mutex> lock(this->game_thread_wait_mutex);
		}
	}
}

/**
 * Pause the game-loop for a bit, releasing the game-state lock. This allows,
 * if the draw-tick requested this, the drawing to happen.
 */
void VideoDriver::GameLoopPause()
{
	/* If we are not called from the game-thread, ignore this request. */
	if (std::this_thread::get_id() != this->game_thread.get_id()) return;

	this->game_state_mutex.unlock();

	{
		/* See GameThread() for more details on this lock. */
		std::lock_guard<std::mutex> lock(this->game_thread_wait_mutex);
	}

	this->game_state_mutex.lock();
}

/* static */ void VideoDriver::GameThreadThunk(VideoDriver *drv)
{
	drv->GameThread();
}

void VideoDriver::StartGameThread()
{
	if (this->is_game_threaded) {
		this->is_game_threaded = StartNewThread(&this->game_thread, "ottd:game", &VideoDriver::GameThreadThunk, this);
	}

	DEBUG(driver, 1, "using %sthread for game-loop", this->is_game_threaded ? "" : "no ");
}

void VideoDriver::StopGameThread()
{
	if (!this->is_game_threaded) return;

	this->game_thread.join();
}

void VideoDriver::Tick()
{
	if (!this->is_game_threaded && std::chrono::steady_clock::now() >= this->next_game_tick) {
		this->GameLoop();

		/* For things like dedicated server, don't run a separate draw-tick. */
		if (!this->HasGUI()) {
			::InputLoop();
			::UpdateWindows();
			this->next_draw_tick = this->next_game_tick;
		}
	}

	auto now = std::chrono::steady_clock::now();
	if (this->HasGUI() && now >= this->next_draw_tick) {
		this->next_draw_tick += this->GetDrawInterval();
		/* Avoid next_draw_tick getting behind more and more if it cannot keep up. */
		if (this->next_draw_tick < now - ALLOWED_DRIFT * this->GetDrawInterval()) this->next_draw_tick = now;

		/* Keep the interactive randomizer a bit more random by requesting
		 * new values when-ever we can. */
		InteractiveRandom();

		this->InputLoop();

		/* Check if the fast-forward button is still pressed. */
		if (fast_forward_key_pressed && !_networking && _game_mode != GM_MENU) {
			ChangeGameSpeed(true);
			this->fast_forward_via_key = true;
		} else if (this->fast_forward_via_key) {
			ChangeGameSpeed(false);
			this->fast_forward_via_key = false;
		}

		{
			/* Tell the game-thread to stop so we can have a go. */
			std::lock_guard<std::mutex> lock_wait(this->game_thread_wait_mutex);
			std::lock_guard<std::mutex> lock_state(this->game_state_mutex);

			this->LockVideoBuffer();

			this->DrainCommandQueue();

			while (this->PollEvent()) {}
			::InputLoop();

			/* Prevent drawing when switching mode, as windows can be removed when they should still appear. */
			if (_game_mode == GM_BOOTSTRAP || _switch_mode == SM_NONE || HasModalProgress()) {
				::UpdateWindows();
			}

			this->PopulateSystemSprites();
		}

		this->CheckPaletteAnim();
		this->Paint();

		this->UnlockVideoBuffer();
	}
}

void VideoDriver::SleepTillNextTick()
{
	auto next_tick = this->next_draw_tick;
	auto now = std::chrono::steady_clock::now();

	if (!this->is_game_threaded) {
		next_tick = min(next_tick, this->next_game_tick);
	}

	if (next_tick > now) {
		std::this_thread::sleep_for(next_tick - now);
	}
}