opengl_timer.h

/********************************************************************
 * Copyright (C) 2015 Liangliang Nan <liangliang.nan@gmail.com>
 * https://3d.bk.tudelft.nl/liangliang/
 *
 * This file is part of Easy3D. If it is useful in your research/work,
 * I would be grateful if you show your appreciation by citing it:
 * ------------------------------------------------------------------
 *      Liangliang Nan.
 *      Easy3D: a lightweight, easy-to-use, and efficient C++ library
 *      for processing and rendering 3D data.
 *      Journal of Open Source Software, 6(64), 3255, 2021.
 * ------------------------------------------------------------------
 *
 * Easy3D is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License Version 3
 * as published by the Free Software Foundation.
 *
 * Easy3D 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/>.
 ********************************************************************/
 
#ifndef EASY3D_RENDERER_OPENGL_TIMER_H
#define EASY3D_RENDERER_OPENGL_TIMER_H
 
namespace easy3d {
 
    class OpenGLTimer
    {
    public:
        // start the new timer by default.
        explicit OpenGLTimer(bool start_timing = true);
        virtual ~OpenGLTimer();
 
        // Start the timer. The next OpenGL call will be the first timed.
        // This must be called from a thread with the OpenGL context bound.
        void    start();
 
        // Is the timer running.
        bool    is_running() const { return running_; }
 
        // Stop the timer (the previous OpenGL call will be the last timed).
        // This must be called from a thread with the OpenGL context bound.
        void    stop();
 
        // return the GPU time consumed since last start (in milliseconds).
        double  time();
 
    protected:
        unsigned int query_id_;
        bool         running_;
    };
 
}
 
 
#endif  // EASY3D_RENDERER_OPENGL_TIMER_H