OpenGL绘制球

有俩角度 a 是球面点与z轴正方向夹角 另一个是b 是连线在xy这个面的投影与x正轴夹角  R作为球半径

每个点的xyz z很好看出来 就是R*cosa

          R*sina得到在xy平面投影 还需要带入b夹角 b [-180=>180],x=R*sina*cosb;

                                                                                         y=R*sina*sinb;

for (a = 0; a <= 180; a += 1)
  {
    glBegin(GL_LINE_LOOP);
    for (b = 0; b <= 360; b += 1)
    {
      glVertex3f(
        R*sin(transradian(a))*cos(transradian(b)),
        R*sin(transradian(a))*sin(transradian(b)),
        R*cos(transradian(a))
      );
      glVertex3f(
        sin(transradian(a))*cos(transradian(b)),
        sin(transradian(a))*sin(transradian(b)),
        cos(transradian(a))
      );
    }
    glEnd();

  }