OnSize(UINT nType, int cx, int cy)
{
glViewport( 0, 0, cx, cy );
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
glOrtho( 0, cx, cy, 0, 0, 1 );
m_nWidth = cx;
m_nHeight = cy;
}
You need to redraw all your frame related to new screen size.
onDrawFrame()
{
}