glMatrixMode GL_PROJECTION
glLoadIdentity
glOrtho -2 2 -2 2 -5 5
glMatrixMode GL_MODELVIEW
glLoadIdentity
glColor 1 1 1
glBegin GL_QUADS
glVertex3 -1 -1 -5
glVertex3 1 -1 -2
glVertex3 1 1 -2
glVertex3 -1 1 -5
glEnd
