💿🐜 Antkeeper source code
https://antkeeper.com
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83 lines
2.5 KiB
83 lines
2.5 KiB
/*
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* Copyright (C) 2023 Christopher J. Howard
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*
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* This file is part of Antkeeper source code.
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*
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* Antkeeper source code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Antkeeper source code is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <engine/utility/frame-scheduler.hpp>
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#include <algorithm>
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#include <thread>
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frame_scheduler::frame_scheduler() noexcept
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{
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m_frame_start_time = clock_type::now();
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}
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void frame_scheduler::tick()
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{
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// Measure duration of previous frame
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m_frame_end_time = clock_type::now();
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m_frame_duration = m_frame_end_time - m_frame_start_time;
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// Idle until the minimum frame duration has passed
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if (m_frame_duration < m_min_frame_duration)
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{
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// Determine time to idle until
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const time_point_type idle_time = m_frame_end_time + m_min_frame_duration - m_frame_duration;
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// Idle
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do
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{
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std::this_thread::yield();
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m_frame_end_time = clock_type::now();
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}
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while (m_frame_end_time < idle_time);
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// Measure duration of previous frame with idle
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m_frame_duration = m_frame_end_time - m_frame_start_time;
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}
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// Accumulate previous frame duration (with limit to prevent "spiral of death")
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m_accumulated_time += std::min<duration_type>(m_max_frame_duration, m_frame_duration);
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// Start measuring duration of next frame
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m_frame_start_time = m_frame_end_time;
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// Perform fixed-rate updates
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while (m_accumulated_time >= m_fixed_update_interval)
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{
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m_fixed_update_callback(m_fixed_update_time, m_fixed_update_interval);
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m_fixed_update_time += m_fixed_update_interval;
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m_accumulated_time -= m_fixed_update_interval;
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}
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// Perform variable-rate update
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m_variable_update_callback(m_fixed_update_time, m_fixed_update_interval, m_accumulated_time);
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}
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void frame_scheduler::refresh() noexcept
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{
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m_accumulated_time = duration_type::zero();
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m_frame_duration = duration_type::zero();
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m_frame_start_time = clock_type::now();
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}
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void frame_scheduler::reset() noexcept
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{
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m_fixed_update_time = duration_type::zero();
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refresh();
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}
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