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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program 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, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include "common/std/thread.h"
#include "ags/engine/ac/timer.h"
#include "ags/shared/core/platform.h"
#include "ags/engine/ac/sys_events.h"
#include "ags/engine/platform/base/ags_platform_driver.h"
#include "ags/ags.h"
#include "ags/globals.h"
namespace AGS3 {
namespace {
const auto MAXIMUM_FALL_BEHIND = 3; // number of full frames
}
std::chrono::microseconds GetFrameDuration() {
if (_G(framerate_maxed)) {
return std::chrono::microseconds(0);
}
return _G(tick_duration);
}
int setTimerFps(int new_fps) {
assert(new_fps >= 0);
if (new_fps <= 0)
return _G(framerate);
int old_fps = _G(framerate);
_G(tick_duration) = std::chrono::microseconds(1000000LL / new_fps);
_G(framerate) = new_fps;
_G(framerate_maxed) = new_fps >= 1000;
// Update next frame time
_G(next_frame_timestamp) = _G(last_tick_time) + _G(tick_duration);
return old_fps;
}
bool isTimerFpsMaxed() {
return _G(framerate_maxed);
}
void WaitForNextFrame() {
const auto now = AGS_Clock::now();
const auto frameDuration = GetFrameDuration();
// early exit if we're trying to maximise framerate
if (frameDuration <= std::chrono::milliseconds::zero()) {
_G(last_tick_time) = _G(next_frame_timestamp);
_G(next_frame_timestamp) = now;
// suspend while the game is being switched out
while (_G(game_update_suspend) && !_G(want_exit) && !_G(abort_engine)) {
sys_evt_process_pending();
_G(platform)->YieldCPU();
}
return;
}
// jump ahead if we're lagging
if (_G(next_frame_timestamp) < (now - MAXIMUM_FALL_BEHIND * frameDuration)) {
_G(next_frame_timestamp) = now;
}
if (_G(next_frame_timestamp) > now) {
auto frame_time_remaining = _G(next_frame_timestamp) - now;
std::this_thread::sleep_for(frame_time_remaining);
}
_G(last_tick_time) = _G(next_frame_timestamp);
_G(next_frame_timestamp) += frameDuration;
// suspend while the game is being switched out
while (_G(game_update_suspend) && !_G(want_exit) && !_G(abort_engine)) {
sys_evt_process_pending();
_G(platform)->YieldCPU();
}
}
void skipMissedTicks() {
_G(last_tick_time) = AGS_Clock::now();
_G(next_frame_timestamp) = AGS_Clock::now();
}
} // namespace AGS3
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