Access violation reading location 0x00000000 ошибка

Hi all, i have a problem loading models into my game engine which i use wxWidgets for the GUI.
The problem is that whenever i use my Import function it will crash when i have 2+ panels opened which both of them uses/contains a canvas consisting of wxGLCanvas.
the weird thing is that i can load models in either of them (either the first window OR the second, not both!) but then i try to open a model into the other and it instantly crash… it point me to a location in textmeasure.cpp which should be used by wxWidgets, and i will leave the important code here for you guys to see if there is something i have overlooked…

wxWindow *current_page = m_auinotebook1->GetCurrentPage();
	int current_page_index = m_auinotebook1->GetPageIndex(current_page);
	wxString current_label = m_auinotebook1->GetPageText(current_page_index);
	
	wxFileDialog OpenDialog(
		this, _("Choose a file to open"), wxEmptyString, wxEmptyString, _("Fbx files (*.fbx)|*.fbx|Collada files (*.dae)|*.dae|Obj files (*.obj)|*.obj|Quake 2 models (*.md2)|*.md2|Doom 3 models (*.md5mesh)|*.md5mesh"), wxFD_OPEN, wxDefaultPosition);
	
	// Creates a "open file" dialog with 4 file types
	if (OpenDialog.ShowModal() == wxID_OK) // if the user click "Open" instead of "Cancel"
	{
		if (canvas3Ds.size() > 0)
		{
			for (std::vector<Viewport3D *>::iterator iter = canvas3Ds.begin(); iter != canvas3Ds.end(); iter++)
			{
				if (current_label == (*iter)->getTitle())
				{
					//Model loading code inserted here!
				}
			}
		}
		OpenDialog.Close();
	}

the getTitle() function is basically a function that works the same way as GetLabel() for the Viewport3D.

Thanks,
David.

Except for missing sanity checks for the return values of GetCurrentPage() and GetCurrentPageIndex() there is nothing relevant in that code.

Run the code under a debugger and get the exact location where it crashes and a call stack / backtrace.

doublemax wrote:Except for missing sanity checks for the return values of GetCurrentPage() and GetCurrentPageIndex() there is nothing relevant in that code.

Run the code under a debugger and get the exact location where it crashes and a call stack / backtrace.

Hi doublemax, i did what you told me to regarding the debugging, and it appears it crashes at line: 167 in evtloop.cpp.

the line has this code:

i don’t know, i just tried with using F11 instead of F10 and now it says it needs a file called delete_scalar_size.cpp
and i don’t know if wxWidgets is supposed to have such file but it isn’t in my wxWidgets-master folder!

but the last error says it is at line 1546 in string.h (wxWidgets kind of string of course )

and the code at that line has this:

return wxPrivate::wxStringAsBufHelper<T>::Get(*this, len);

i am currently using the newest version of wxWidgets (upgraded yesterday!)

Alright doublemax, i have finally figured out the source of the problem…

it is when i load a model into one of the scenes, and when i try to load the same model directly into the other scene then it crashes because i think that OpenDialog returns the same string value on scene 2 as scene 1! but how to fix it, i don’t know.

it is when i load a model into one of the scenes, and when i try to load the same model directly into the other scene then it crashes because i think that OpenDialog returns the same string value on scene 2 as scene 1!

I don’t see any code that reads the path from the wxFileDialog, so i don’t know what your code is doing there.

If a crash happens somewhere inside the wxWidgets code, the interesting part of the call stack are the last lines in *your* code that lead to the crash.

doublemax wrote:

it is when i load a model into one of the scenes, and when i try to load the same model directly into the other scene then it crashes because i think that OpenDialog returns the same string value on scene 2 as scene 1!

I don’t see any code that reads the path from the wxFileDialog, so i don’t know what your code is doing there.

If a crash happens somewhere inside the wxWidgets code, the interesting part of the call stack are the last lines in *your* code that lead to the crash.

Thanks doublemax i’ll check it out when i can get to the pc again!

i just got this on the pc in Visual studio 2015:

> Editor.exe!wxTextMeasure::DoGetTextExtent(const wxString & string, int * width, int * height, int * descent, int * externalLeading) Line 127 C++

this is the last line of the callstack

> Editor.exe!wxTextMeasure::DoGetTextExtent(const wxString & string, int * width, int * height, int * descent, int * externalLeading) Line 127 C++

this is the last line of the callstack

Like i said, the interesting part is the last line in your code that got executed. Because there you must pass some invalid data into a wxWidgets method.

doublemax wrote:

> Editor.exe!wxTextMeasure::DoGetTextExtent(const wxString & string, int * width, int * height, int * descent, int * externalLeading) Line 127 C++

this is the last line of the callstack

Like i said, the interesting part is the last line in your code that got executed. Because there you must pass some invalid data into a wxWidgets method.

Ohh, sorry for my stupidity i am not fully woken yet i will try and investigate it further Thanks for your help once again doublemax.