C++ opengl 线段的绘制

每两个点一条线，已经连接的点不能连线！
程序运行截图如下：

伪代码如下：

void Draw() {
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    glLineWidth(10.0f);
    glBegin(GL_LINES);
    glColor4ub(255, 0, 0, 255); glVertex3f(-0.5f, -0.25f, -2.5f);
    glColor4ub(0, 0, 255, 255); glVertex3f(0.5f, -0.25f, -2.5f);
    glColor4ub(0, 0, 255, 255); glVertex3f(0.5f, -0.25f, -2.5f);
    glColor4ub(0, 255, 0, 255); glVertex3f(1.0f, 0.5f, -2.5f);
    glEnd();
}