void GameManager::reshape(GLsizei w, GLsizei h){
		float xmin = -4., xmax = 4., ymin = -6., ymax = 6.;
		float ratio = (xmax - xmin) / (ymax - ymin);
		float aspect = (float)w / h;
		if (aspect > ratio)
			glViewport((w - h*ratio) / 2, 0, h*ratio, h);
		else
			glViewport(0, (h - w / ratio) / 2, w, w / ratio);
		glMatrixMode(GL_PROJECTION);
		glLoadIdentity();
		glMatrixMode(GL_MODELVIEW);
		glLoadIdentity();
		gluOrtho2D(xmin, xmax, ymin, ymax);
}