glClear(GL_COLOR_BUFFER_BIT);

	float z = 1.0;
	float w = 0.5;

	glColor3f(1.0, 1.0, 0.0);

	glBegin(GL_POLYGON);
		glVertex3f(w, w, z);
		glVertex3f(w, -w, z);
		glVertex3f(-w, -w, z);
		glVertex3f(-w, w, z);
	glEnd();

	glFlush();