title: OpenGL 2D rotation problem
body: <p>In the following program i am trying to draw a simple house. The coordinates are defined in the house array. I need to rotate the house and display both rotated as well as the original house. 
  But why is the rotated house not being displayed?</p>
  
  <pre><code>    //Program to create a house like figure and rotate ir about a given fixed point using OpenGL functions.
  #include &lt;glut.h&gt;
  #include &lt;stdio.h&gt;
  
  float house [11][2] = {{100,200},{200,250},{300,200},{100,200},{100,100},{175,100},{175,150},{225,150},{225,100},{300,100},{300,200}};
  
  void init()
  {
      glClearColor(1,1,1,0);
      glMatrixMode(GL_PROJECTION);
      gluOrtho2D(0,800,0,800);
      glMatrixMode(GL_MODELVIEW);
  }
  
  void display()
  {
      glClear(GL_COLOR_BUFFER_BIT);
  
      //NORMAL HOUSE
      glColor3f(1,0,0);
      glBegin(GL_LINE_LOOP);
  
      for(int i=0;i&lt;11;i++)
          glVertex2fv(house[i]);
      glEnd();
      glFlush();
  
  
      //ROTATED HOUSE
      glPushMatrix();
      glRotatef(60,0,1,0);
      glColor3f(1,1,0);
      glBegin(GL_LINE_LOOP);
  
      for(int i=0;i&lt;11;i++)
          glVertex2fv(house[i]);
      glEnd();
      glFlush();
      glPopMatrix();
  }
  
  void main(int argc,char** argv)
  {
      glutInit(&amp;argc,argv);
      glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
      glutInitWindowSize(800,800);
      glutInitWindowPosition(100,100);
      glutCreateWindow("House rotation");
      init();
      glutDisplayFunc(display);
      glutMainLoop();
  }
  </code></pre>