Program crashes on calling virtual function

[manuthomas23@gmail.com]

Here is the code:

#ifndef M3DCAMERA__H__
#define M3DCAMERA__H__

class M3DEngine;

/**
Micro3D Camera class.
*/
class M3DCam
{
public:
virtual void Init(EngineData *ed);

[Ben Pope]

Re: Program crashes on calling virtual function

manuthomas23@gm ail.com wrote:[color=blue]
> Here is the code:[/color]

What code?
[color=blue]
> #ifndef M3DCAMERA__H__
> #define M3DCAMERA__H__
>
> class M3DEngine;
>
> /**
> Micro3D Camera class.
> */
> class M3DCam
> {
> public:
> virtual void Init(EngineData *ed);
> .
> .
> .
> protected:
> IMicro3D *m_pmicro3d; ///<Micro3D interface pointer.
> Vec3i m_pos; ///<Position of the camera.
> Vec3i m_target; ///<Target of the camera.
> Vec3i m_up; ///<Camera up direction vector.
> Atrans3i m_cam_mat; ///<Camera matrix.
> };[/color]

What is EngineData?
What is an IMicro3D?
What is a Vec3i?
What is an Atrans3i?
My compiler isn't fond of the dots, either.
[color=blue]
> /**
> Free moving Camera.
> */
> class M3DFreeCam : public M3DCam
> {
> public:
> void Init(EngineData *ed);
> void CleanUp(void);
>
> .
> .
> .
> .
> private:
> hi_sint32 m_cam_ang; ///<Angle of rotation of camera w.r.t Y axis.
> Vec3i m_dir; ///<Direction vector of movement.
> };[/color]

What is hi_sint32?
[color=blue]
> /**
> Base Engine class.
> */
> class Engine : public EngineData
> {
> private:
>
> M3DFreeCam m_cam;
> .
> .
> .
> }
>
> /**
> Initialize the game engine.
> \return TRUE if success.
> */
> BOOL Engine::Init(vo id)
> {
> BOOL res = TRUE;
>
> EngineData::Ini t();
>
> SetGameState((G SFunc)Engine::G S_Game, GS_GAME);[/color]

<<-- CAST ABOVE

What is GSFunc?
[color=blue]
> m_cam.Init(this ); <<-----------CRASHES HERE[/color]



Remove the cast. Fix the problem properly.

If you want us to help, post complete, compilable code. Don't add
extraneous dots, as they don't compile.

Ben Pope
--
I'm not just a number. To many, I'm known as a string...

[Fei Liu]

Re: Program crashes on calling virtual function


manuthomas23@gm ail.com wrote:[color=blue]
> Here is the code:
>
> #ifndef M3DCAMERA__H__
> #define M3DCAMERA__H__
>
> class M3DEngine;
>
> /**
> Micro3D Camera class.
> */
> class M3DCam
> {
> public:
> virtual void Init(EngineData *ed);
> .
> .
> .
> protected:
> IMicro3D *m_pmicro3d; ///<Micro3D interface pointer.
> Vec3i m_pos; ///<Position of the camera.
> Vec3i m_target; ///<Target of the camera.
> Vec3i m_up; ///<Camera up direction vector.
> Atrans3i m_cam_mat; ///<Camera matrix.
> };
>
> /**
> Free moving Camera.
> */
> class M3DFreeCam : public M3DCam
> {
> public:
> void Init(EngineData *ed);
> void CleanUp(void);
>
> .
> .
> .
> .
> private:
> hi_sint32 m_cam_ang; ///<Angle of rotation of camera w.r.t Y axis.
> Vec3i m_dir; ///<Direction vector of movement.
> };
>
> /**
> Base Engine class.
> */
> class Engine : public EngineData
> {
> private:
>
> M3DFreeCam m_cam;
> .
> .
> .
> }
>
> /**
> Initialize the game engine.
> \return TRUE if success.
> */
> BOOL Engine::Init(vo id)
> {
> BOOL res = TRUE;
>
> EngineData::Ini t();
>
> SetGameState((G SFunc)Engine::G S_Game, GS_GAME);
>
> m_cam.Init(this ); <<-----------CRASHES HERE
> m_cam.MoveForwa rd(10);
> m_m3dengine.Sel ectCamera(&m_ca m);
>
> xit:
> return res;
> }
>
> Here m_cam is a member variable in Engine. It is of type
> M3DFreeCam(deri ved from MD3Cam). Init() is a virtual function. But when
> I call m_cam.Init(this ), the program crashes!
>
> (Unhandled exception at 0x00f09f33 (pool.dll) in BREW_Emulator.e xe:
> 0xC0000005: Access violation reading location 0x00000000.)
>
> If I make m_cam a local variable(instea d of member variable),
> inside Engine::Init(), it works fine, no crashes. I wonder why this is
> happening. Could anyone please explain this to me?
>
> Thanks in advance.[/color]

It seems something is messed in the initialization order. It's not
clear what the problem is from the code snippets you have posted.