Berlin000000 / learnopengl-qt

learn opengl with Qt / learnopengl 的 Qt 版本

learnopengl-qt

learn opengl with Qt, and it's directory structure is mostly like the origin one.

How to use

install libraries

• download Qt
• install assimp and make sure that the lib path is correct in learnopengl-qt.pro bottom line LIBS += -L$$PWD/thirdparty/assimp_x64-windows/lib/ -lassimp-vc141-mt
• this project is build in Qt 5.9.9 MSVC2017 64bit, the compiled library is in ./thirdparty/, make sure *.dll is in the same path with *.exe

run

• open the file learnopengl-qt.pro with QtCreator

• run it in debug/release mode

• select a widget to show

  

How to add a new widget

• create a new class like this

  class MultipleLights : public QOpenGLWidget, protected QOpenGLFunctions_3_3_Core
  {
      Q_OBJECT
  public:
      //Q_INVOKABLE is needed
      Q_INVOKABLE MultipleLights(QWidget *parent = nullptr);
      ~MultipleLights();
  
  protected:
      virtual void initializeGL() override;
      virtual void resizeGL(int w, int h) override;
      virtual void paintGL() override;
  
  private:
  };

• inclue it in MainWindow.h

  #include "2.lighting/6.1multiple_lights/MultipleLights.h"

• add the class name and staticMetaObject to a hashMap in MainWindow.cpp

  void MainWindow::registerMetaObject()
  {
      //add staticMetaObject of the new class you have created to a list
      m_metaObjectList << &MultipleLights::staticMetaObject;
  
      //then easily traverse the list and add QMetaObject to map and combox
      for(const QMetaObject* mo : m_metaObjectList){
          m_metaObjectMap.insert(mo->className(), mo);
          m_combox->addItem(mo->className());
      }
  }

Notes

1. glBindFramebuffer(GL_FRAMEBUFFER, 0) may not work in QOpenGLWidget, because 0 is not QOpenGLWidget's default framebuffer, use glBindFramebuffer(GL_FRAMEBUFFER, defaultFramebufferObject())instead. Here is my blog

2. It seems that Qt does not have UBO(uniform buffer object), thus I made a class called OpenGLUniformbufferObject. And, you must pay attention:

   // wrong
   class OpenGLUniformbufferObject : public QOpenGLFunctions_3_3_Core
   {
       //...
       glGetActiveUniformBlockiv(m_shaderId, m_uniformBlockIndex, GL_UNIFORM_BLOCK_DATA_SIZE, &m_uboSize);
   }
   // right
   class OpenGLUniformbufferObject
   {
       //...
       // get current opengl function
       QOpenGLFunctions_3_3_Core* m_glFunc = QOpenGLContext::currentContext()->versionFunctions<QOpenGLFunctions_3_3_Core>();
       m_glFunc->glGetActiveUniformBlockiv(m_shaderId, m_uniformBlockIndex, GL_UNIFORM_BLOCK_DATA_SIZE, &m_uboSize);
   }