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