glVertex3f(0,0,0);glVertex3f(0.0,0.0,5.0);这个垂直于屏幕，永远不会被绘制。另外glOrtho (-1.0, 1.0, -1.0, 1.0, 1.5, 20.0);设定了Z坐标为（-1.5到-20.0）的才会被复制，可是你画的两条线
glVertex3f(0,0,0);glVertex3f(5.0,0.0,0.0);glVertex3f(0,0,0);glVertex3f(0.0,5.0,0.0); 都不在（-1.5~-20.0）范围内，所以不会被绘制。修改成glOrtho (-1.0, 1.0, -1.0, 1.0, 0.0, 20.0);显示正常。求分~~~... |
