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OpenCV error by using OpenGL

asked 2013-11-09 05:50:18 -0500

Nightrush0179 gravatar image

updated 2013-11-09 05:57:28 -0500

Hi, I am trying to copy a Mat in a ogl::Texture2D.

void CVMat_ImageWidget::setImage(cv::Mat img)
{
    cv::ogl::Texture2D texture(img);

    //...
}

But I always get the error "OpenCV Error: OpenGL API call (Can't load OpenGL extension [glBindBuffer]) in IntGetProcAddress, file C:\LIBS\OpenCV_2_4_6\src\opencv\modules\core\src\gl_core_3_1.cpp, line 141". I built OpenCV (2.4.6) with OpenGL so this shouldn´t be the problem. What is the problem ?

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answered 2014-08-06 08:59:45 -0500

protonmesh gravatar image

I was having the same problem. My mistake:

Making OpenGL calls, for example like the one you posted: cv::ogl::Texture2D texture(img);

without first having an OpenGL context current on the calling thread. Because a texture2D needs to be created within a certain encapsulated context.

The OpenGL context can constructed either through the OpenCV provided HighGUI module, using namedWindow(<window_name>, WINDOW_OPENGL), which creates a new window and corresponding OpenGL context, and sets the context of that window active (look at setOpenGLContext(..) for switches between contexts of multiple namedWindows ) .

The context can also be created through 3rd party windowing / multimedia libraries (GLUT, OpenTK, SDL, GLFW, etc.) or full blown UI toolkits (Qt, wxWidgets) (see https://www.opengl.org/wiki/Related_toolkits_and_APIs). Whichever library you use to create the context, ensure that the context is made active (the library should provide a method for this) and all subsequent calls from the ogl:: namespace should work.

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answered 2014-07-29 01:31:52 -0500

MRDaniel gravatar image

updated 2014-07-29 01:32:52 -0500

Hi.

You need to do a little more work than this.

int loadTexture_Ipl(IplImage *image, GLuint *text) {

if (image==NULL) return -1;

glGenTextures(1, text);

glBindTexture( GL_TEXTURE_2D, *text ); //bind the texture to it's array

glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);

glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);

glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, image->width, image->height,0, GL_BGR, GL_UNSIGNED_BYTE, image->imageData);

return 0;

}

The above is pretty old school. Are there no examples?

Clearly you are using a cv::Mat but i think you can use cv::Mat.data in place of when defining the texture.

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Comments

1

please, anything with IplImages in it is not old school, but plain outdated.

berak gravatar imageberak ( 2014-07-29 01:35:27 -0500 )edit
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Asked: 2013-11-09 05:50:18 -0500

Seen: 677 times

Last updated: Aug 06 '14