How to sue glMapBuffers/glUnmapBuffer with QGLWidget?

[jshafferman]

I am trying to follow the OpenGL Superbible (4th Edition) example (ThunderbirdGL) and they have a function glMapBuffers() in a VBOMesh.cpp file and I can't get that function to be recognized by any header that is included with GL. Am I missing something simple?

///////////////////////////////////////////////////////////////////////////
 
// Scale of the vertices. The only way to do this is to map the VBO back
 
// into client memory, then back again
 
void CVBOMesh::Scale(GLfloat fScaleValue)
 
{
 
    glFuncs.glBindBuffer(GL_ARRAY_BUFFER, bufferObjects[VERTEX_DATA]);
 
    M3DVector3f *pVertexData = (M3DVector3f *)glMapBuffer(GL_ARRAY_BUFFER, GL_READ_WRITE);
 
 
 
    if(pVertexData != NULL)
 
    {
 
        for(unsigned int i = 0; i < nNumVerts; i++)
 
            m3dScaleVector3(pVertexData[i], fScaleValue);
 
 
 
        glUnmapBuffer(GL_ARRAY_BUFFER);
 
    }
 
}

///////////////////////////////////////////////////////////////////////////

// Scale of the vertices. The only way to do this is to map the VBO back

// into client memory, then back again

void CVBOMesh::Scale(GLfloat fScaleValue)

{

    glFuncs.glBindBuffer(GL_ARRAY_BUFFER, bufferObjects[VERTEX_DATA]);

    M3DVector3f *pVertexData = (M3DVector3f *)glMapBuffer(GL_ARRAY_BUFFER, GL_READ_WRITE);



    if(pVertexData != NULL)

    {

        for(unsigned int i = 0; i < nNumVerts; i++)

            m3dScaleVector3(pVertexData[i], fScaleValue);



        glUnmapBuffer(GL_ARRAY_BUFFER);

    }

}

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The error I see from the compiler is:
../shared/VBOMesh.cpp:204: error: 'glMapBuffer' was not declared in this scope
../shared/VBOMesh.cpp:211: error: 'glUnmapBuffer' was not declared in this scope

where shared is the folder that VBOMesh is in.

http://www.opengl.org/sdk/docs/man/x...lMapBuffer.xml reference for glMapBuffer
http://www.opengl.org/sdk/docs/man4/...lMapBuffer.xml reference for glUnmapBuffer

Any help would be awesome! Thanks

[wysota]

Did you include GL.h?

[jshafferman]

Yup I still get the same error after I use this include
#include <GL/gl.h>

VBOMesh.h has #include <QtOpenGL> passed into it from a different header in case your curious.

Just an FYI, I am trying to use mostly Qt related stuff because I am doing all my opengl stuff in QGLWidget. Also I am using Qt 4.8.4 because that is the same version we use at my office and eventually we will be doing Opengl stuff in our widget. Finally the reason I am using Opengl Superbible 4th edition is because that is the superbible edition that matches our products opengl capability set (2.0, 2.1, and ES 2.0)

[wysota]

I never used glMapBuffer so I might be wrong but don't you have to query for this function using dlsym/getprocaddress first?

[stampede]

Yes, this function needs to be loaded. I have always used GLEW (The OpenGL Extension Wrangler Library) to load additional functions, simply include glew before gl.h:

#include <GL/glew.h>
#include <GL/gl.h>
...

#include <GL/glew.h>
#include <GL/gl.h>
...

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and link with -lGLEW.
More info here : GLEW