I''m having problems with graphics engine I''m working on. I''m currently trying to learn OOP for C++ and I thought that it would be ideal for my graphics engine because I want to implement an number of draw modes. ie Software, OpenGL, etc; So I have got as follows at the moment:

  
class Engine
{
public:
  Engine() {};
  ~Engine() {};
  virtual setup() = 0;
  virtual draw() = 0;
};

class OpenGLEngine: public Engine
{
  OpenGLEngine() {// int stuff}

  ~OpenGLEngine () {//destroy stuff}

  setup();
  draw();  
};
[/source]

Then in the main program I have got...
[source]
Engine *pGfxEngine;

switch(MODE)
{
case RENDER_SOFTWARE:
  ...
  break;
case RENDER_OPENGL:
  pGfxEngine = new OpenGLEngine();
  break;
}
  

Anyway when I want to destroy the OpenGLEngine it will not call the OpenGLEngine destructor only the Engine desctructor. Thanks for any help.

Make your destructor virtual.

Edited by - Jrz on December 21, 2000 11:15:05 AM

Jrz is right.

Because pGfxEngine is initially an object of Engine. You are using polymorphism to access your derived class. And so when you destroy pGfxEngine it is calling Engine::~Engine() not OpenGlEngine::~OpenGlEngine(). If it was virtual, it would then call ~OpenGLEngine() before ~Engine().

Kevin =)

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