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Closed beta test for Goblin XNA 4.0

Mar 14, 2011 at 10:18 PM

Hi all,

We'd like to distribute a closed beta version of Goblin XNA 4.0 for those who are interested in testing their applications with XNA 4.0. 

Please send an email to if you're interested in, and please report me any bugs you find.



Mar 26, 2011 at 5:14 AM

hello my name is fernando chile Yevenes'm with a friend we are looking at reality augmented, sorry if my English is bad, my friend we meet once a week to study XNA, day, usually Saturday, I'm programmer for 6 years , well I hope to find out about this error any greetings

fernando Yevenes

Apr 22, 2011 at 9:18 PM

Goblin XNA 4.0 beta test.

I can compile and run this beta version ok with all the tutorial except Tutorial 8. Here is the error that I have and don't know how to pass this.

Tutorial 8:

When compile in debug mode, I have the output on console as:

Alvar Library 1.5.0
Copyright 2008-2010 VTT Technical Research Centre of Finland
Compiled on Windows 5.1 x86 on Jan  4 2011
Licensed to Public (00000000000000000000)
Day 108/365 of usage period for this licence

Then it throw an exception called "AccessViolationException"

Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

This is happen at line 420 of ALVARMarkerTracker.cs:


Any clue how to fix this?

Thank you so much for your great work

Apr 22, 2011 at 10:40 PM

Further track down to the above issue, it seems that the method alvar_add_multi_marker() is defined in ALVARDllBridge.cs as an external method coming from ALVARWrapper.dll.


This ALVARWrapper.dll is a result when compile from ALVARWrapper1.5.


Although, I compile ALVARWrapper1.5 successfully, but the ALVARWrapper.dll does have problem???

Continue... search for the root cause!!!

Apr 22, 2011 at 11:49 PM


One more level to the wrapper code, there is an odd thing as:

The method alvar_add_multi_marker() declared in MarkerDetectorWrapper.cpp has a signature as:

__declspec(dllexport) void alvar_add_multi_marker(int num_ids, int* ids, char* filename)

But when it is re-declared in ALVARDllBridge.cs, it becomes:

public static extern void alvar_add_multi_marker(String filename);

I don't really understand this?


Apr 23, 2011 at 2:02 AM

It's hard to tell what the problem might be.  AccessViolationException usually means you have a version mismatch between your executables.  Are you sure you installed OpenCV1.0 and not 2.x?  Currently, Alvar is developed to work with an older version of OpenCV.  It seems like you have Alvar 1.5, which is correct.

Apr 23, 2011 at 2:14 AM

I just realized that for closedBeta4.0 version, the wrapper needs to be the latest version (not the version on SVN, which is for 3.5.1). Please replace the alvar_add_multi_marker function with the following code and recompile the wrapper:

__declspec(dllexport) void alvar_add_multi_marker(char* filename)
		MultiMarker marker;
		if(strstr(filename, ".xml") != NULL)
			marker.Load(filename, FILE_FORMAT_XML);

Apr 23, 2011 at 6:51 AM
Edited Apr 25, 2011 at 2:38 PM

Thank Ohan, you save me a ton of time!

The update function get me over to this stuck point. The ALVARGroundArray.xml and Toolbar.txt shifted with Tutorial 8 doesn't work, I regenerate these two files using the markerlayout tool, then I can pass the above stuck point.

But then come to other stuck point located at line 546 of ALVARMarkerTracker.cs. This time it is alvar_detect_marker(). I just wonder if we need to update this function also in the wrapper?

In side this function, there is a called to Detect() at line 193 that pass 6 parameters while the definition of this function is in MarkerDetector.h which need to have 8 parameters?

Thanks for shed me a light.

@mengu: I do have both OpenCV1.0 and OpenCV2.x since the later is required by tutorial 13 I think. And yes, I'm running Alvar1.5 for Goblin xna 4.0 beta.

Apr 25, 2011 at 4:42 PM

I think I got it since I miss one of your suggestion about alvar1.5.0. I need to compile this on VS2008 not in 2010.

And with this, it works great now. I don't need to update Detect() function.


Thank you so much guys

Apr 26, 2011 at 10:45 AM

Ah great, I can finally migrate my project to 4.0 :).

Would be nice to have the wrapper in vc2010 too.

Aug 23, 2011 at 1:48 AM

Hi ohanoda!

im wondering if i can obtain Goblin xna 4.0 beta for testing it... im really surprised about the performance of Goblin Xna 3.6 . Thank you for share your knowledge and help people developing things in Goblin.

Carlos A. Knopel

Aug 29, 2011 at 6:58 PM

Sorry, we're not distributing the beta anymore, please wait for the public release. It'll happen sometime in September (may late Sep or early Oct depending on my schedule).