Question

I’ve got a little segment that generates a display list that looks like this:

glNewList ( CDisplayList :: GetBaseList () + 2, GL_COMPILE );
{
    glBegin ( GL_QUADS );           
        glPushMatrix ();

            //
            // Move to slightly lower position.
            //

            glTranslatef ( 0.0f, -1.1f, 0.0f ); 
            glColor4f ( 1.0f, 1.0f, 1.0f, 1.0f );

            //
            // Front facing.
            //

            glTexCoord2f ( m_TexLeft,   m_TexBottom );  glVertex3f ( m_Start, -0.1f, 0.0f );            
            glTexCoord2f ( m_TexRight,  m_TexBottom );  glVertex3f ( m_End, -0.1f, 0.0f );          
            glTexCoord2f ( m_TexRight,  m_TexTop );     glVertex3f ( m_End, -1.3f, 0.0f );          
            glTexCoord2f ( m_TexLeft,   m_TexTop );     glVertex3f ( m_Start, -1.3f, 0.0f );    

            //
            // Back facing.
            //

            glTexCoord2f ( m_TexLeft,   m_TexTop );     glVertex3f ( m_Start, -1.3f, 0.0f );
            glTexCoord2f ( m_TexRight,  m_TexTop );     glVertex3f ( m_End, -1.3f, 0.0f );          
            glTexCoord2f ( m_TexRight,  m_TexBottom );  glVertex3f ( m_End, -0.1f, 0.0f );                          
            glTexCoord2f ( m_TexLeft,   m_TexBottom );  glVertex3f ( m_Start, -0.1f, 0.0f );                            
        glPopMatrix ();
    glEnd ();
}
glEndList ();   

GLenum e = glGetError();

The “e” value at the end here is always 1282 (invalid operation, or something like that). I’m not sure why. I’ve checked glGetError after every command building the list, from the glNewList downwards, and it’s always the same (zero). This display list is one of 3 – 2 of which built ok previously (tested with glGetError and returning zero). So something about this list specifically is giving the driver a headache.

Any ideas?

Note that m_TexLeft, etc. is 0, 0, 1, 0.125 (left, top, right, bottom) and m_Start, m_End is 0, 100. The GetBaseList returns an integer got by calling glGenLists(3) (the exact value is 257).

Can’t see what’s wrong with it to be honest.

Answer 1

You need to move the transformation matrix manipulations out of the glBegin/glEnd pair. This is what the documentation says:

Only a subset of GL commands can be used between glBegin and glEnd.
The commands are glVertex, glColor, glIndex, glNormal, glTexCoord,
glEvalCoord, glEvalPoint, glArrayElement, glMaterial, and glEdgeFlag.
Also, it is acceptable to use glCallList or glCallLists to execute
display lists that include only the preceding commands. If any other
GL command is executed between glBegin and glEnd, the error flag is
set and the command is ignored.

And under the Errors section:

GL_INVALID_OPERATION is generated if a command other than glVertex,
glColor, glIndex, glNormal, glTexCoord, glEvalCoord, glEvalPoint,
glArrayElement, glMaterial, glEdgeFlag, glCallList, or glCallLists is
executed between the execution of glBegin and the corresponding
execution glEnd.