I have just started with my first attempt at a game engine and I have a problem. I was looking for the best way to separate the engine from the game code and decided to use a static library (.lib file) and that works great except one thing.. I don't seem to be able to make a class in my game project inherit a class with virtual members in my engine project. The game project is linked to the engine project correctly and I can use it for everything except inheriting a class with virtual members.
The specific thing I'm doing now is a win32 window wrapper class which is a base class in the engine that each real window in the game will inherit. The virtual method is the wndproc that needs to be different for each window.
> error LNK2001: unresolved external symbol "public: virtual long __stdcall WndMain::wndproc(struct HWND__ *,unsigned int,unsigned int,long)" (?wndproc@WndMain@@UAGJPAUHWND__@@IIJ@Z)
> fatal error LNK1120: 1 unresolved externals
I get this ^^^^^^
note that there are two wndproc methods (stwndproc which is static and is no problem and then there wndproc which is virtual)
basewindow.h (part of engine static library)
class BaseWindow
{
private:
HINSTANCE inst;
HWND wnd;
WNDCLASSEX wc;
char cn[256], t[256];
protected:
BaseWindow(HINSTANCE hInstance);
~BaseWindow();
public:
static LRESULT CALLBACK stwndproc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
virtual LRESULT CALLBACK wndproc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
void create();
void destroy();
// etc
};
basewindow.cpp (part of engine static library)
BaseWindow::BaseWindow(HINSTANCE hInstance)
{
inst = hInstance;
strcpy(cn, "default");
strcpy(t, "untitled");
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = CS_HREDRAW | CS_VREDRAW;
wc.lpfnWndProc = BaseWindow::stwndproc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = inst;
wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
wc.lpszMenuName = 0;
wc.lpszClassName = cn;
wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
}
BaseWindow::~BaseWindow()
{
}
LRESULT CALLBACK BaseWindow::stwndproc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
// irrelevant
}
LRESULT CALLBACK BaseWindow::wndproc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
return DefWindowProc(hWnd, uMsg, wParam, lParam);
}
void Window::create()
{
// irrelevant
}
void Window::destroy()
{
// irrelevant
}
wndmain.h (part of game code)
class WndMain : public BaseWindow
{
public:
WndMain(HINSTANCE hInstance);
~WndMain();
LRESULT CALLBACK wndproc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
};
wndmain.cpp (part of game code)
WndMain::WndMain(HINSTANCE hInstance) : BaseWindow(hInstance)
{
// irrelevant
}
WndMain::~WndMain()
{
// irrelevant
}
LRESULT CALLBACK wndproc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
// irrelevant
}
Does anyone know why this is? I have never used a static library before so maybe the limitation is there?
