26.5 OpenGL in the Pop Framework

Look back at the code for CPopView::OnDraw(CDC* pDC) that we gave in Section 24.4: Graphics in the Pop Framework. Here is a bulleted list showing some of the corresponding OpenGL calls made by the _pgraphics member of CPopView if _pgraphics is of the type cGraphicsOpenGL* .

• Wake up the graphics with

   _pgraphics->activate(). 

  This calls

    ::wglMakeCurrent  ( _pDC->GetSafeHdc(), _hRC ) 

• Clear the graphics background with

   _pgraphics->clear(targetrect). 

  This calls

    ::glClear  ( GL_COLOR_BUFFER_BIT  GL_DEPTH_BUFFER_BIT ); 

• Install the projection and view matrices with these lines.

   _pviewpointcritter->loadProjectionMatrix();  _pviewpointcritter->loadViewMatrix(); 

  These in turn call:

    ::glMatrixMode  (GL_MODELVIEW)  ::glLoadMatrixf  (_pviewpointcritter->attitude().inverse());  ::glMatrixMode  (GL_PROJECTION)  ::gluPerspective  (fieldofviewangleindegrees, xtoyaspectratio,      nearzclip, farzclip); //Values from _pviewpointcritter 

• Draw your game world and then the critters with

   pgame()->drawCritters(_pgraphics, _drawflags). 

  This generates a variety of ::gl and ::glu calls like, in the case of polygons

    ::glEnableClientState  (GL_VERTEX_ARRAY);  ::glVertexPointer  (...);  ::glDrawArrays  (...); 

• Send the graphics to your video display with

   _pgraphics->display(this, pDC) 

  This calls

    ::glFinish  ();// Tell OpenGL to flush its pipeline  ::SwapBuffers  ( _pDC->GetSafeHdc() ); // Now Swap the buffers