opengl_utils.h

Go to the documentation of this file.

// ----------------------------------------------------------------------------
// -                        CloudViewer: www.cloudViewer.org                  -
// ----------------------------------------------------------------------------
// Copyright (c) 2018-2024 www.cloudViewer.org
// SPDX-License-Identifier: MIT
// ----------------------------------------------------------------------------
 
#pragma once
 
#ifdef GUI_ENABLED
#include <QAction>
#include <QApplication>
#include <QOffscreenSurface>
#include <QOpenGLContext>
#include <QThread>
#include <QWaitCondition>
#endif
 
#include "util/threading.h"
 
namespace colmap {
 
#ifdef DEBUG
#define glDebugLog() glError(__FILE__, __LINE__)
#else
#define glDebugLog()
#endif
 
#ifdef GUI_ENABLED
 
// This class manages a thread-safe OpenGL context. Note that this class must be
// instantiated in the main Qt thread, since an OpenGL context must be created
// in it. The context can then be made current in any other thread.
class OpenGLContextManager : public QObject {
public:
    OpenGLContextManager(int opengl_major_version = 2,
                         int opengl_minor_version = 1);
 
    // Make the OpenGL context available by moving it from the thread where it
    // was created to the current thread and making it current.
    void MakeCurrent();
 
    // Check whether the machine has OpenGL and we can create the context.
    static bool HasOpenGL();
 
private:
    QOffscreenSurface surface_;
    QOpenGLContext context_;
    QThread* parent_thread_;
    QThread* current_thread_;
    QAction* make_current_action_;
};
 
// Run and wait for the thread, that uses the OpenGLContextManager, e.g.:
//
//    class TestThread : public Thread {
//     private:
//      void Run() { opengl_context_.MakeCurrent(); }
//      OpenGLContextManager opengl_context_;
//    };
//    QApplication app(argc, argv);
//    TestThread thread;
//    RunThreadWithOpenGLContext(&thread);
//
void RunThreadWithOpenGLContext(Thread* thread);
 
// Get the OpenGL errors and print them to stderr.
void GLError(const char* file, const int line);
 
#else
 
// Dummy implementation when GUI support is disabled
class OpenGLContextManager {
public:
    OpenGLContextManager(int opengl_major_version = 2,
                         int opengl_minor_version = 1) {}
    inline void MakeCurrent() {}
    inline static bool HasOpenGL() { return false; }
};
 
inline void RunThreadWithOpenGLContext(Thread* thread) {}
 
inline void GLError(const char* file, const int line) {}
 
#endif
 
}  // namespace colmap