C++ 剔除截锥体向上或向下看时变窄

我在OpenGL中实现截锥剔除时遇到问题。 我使用本教程在世界空间中实现了平面提取（引擎的其余部分来自learnopengl.com）。 它工作得很好，但只有当相机指向地平线时。如果相机指向上或下，平截头体将逐渐变窄

事实上，当指向地平线时，远平截体平面大小为1023*828，但当指向上或下时，远平截体平面大小仅为17*14。同样的问题也发生在近平截头体平面上

下面是每帧更新平截头体的代码（C++）：

结果如下：

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问题是由于cameraUp和cameraRight值未标准化

  tang = (float) tan(glm::radians(45.0f) * 0.5f);
  ratio = SCR_WIDTH * 1.0 / SCR_HEIGHT;

  // Direction vectors
  cameraZ = cameraFront * -1.0f;
  cameraRight = glm::cross(glm::vec3(0.0f, 1.0f,  0.0f), cameraZ);
  cameraUp = glm::cross(cameraZ, cameraRight);

  // Dimensions of near and far frustum planes
  Hnear = nearDist * tang; // Hnear = near plane height
  Wnear = Hnear * ratio; // Wnear = near plane width
  Hfar = farDist  * tang; // Hfar = far plane height
  Wfar = Hfar * ratio; // Wfar = far plane width

  // Distance of near and far planes
  fc = cameraPos - cameraZ * farDist; // fc = far center
  nc = cameraPos - cameraZ * nearDist; // nc = near center

  // Extraction of frustum points
  ntl = nc + (cameraUp * Hnear) - (cameraRight * Wnear);
  ntr = nc + (cameraUp * Hnear) + (cameraRight * Wnear);
  nbl = nc - (cameraUp * Hnear) - (cameraRight * Wnear);
  nbr = nc - (cameraUp * Hnear) + (cameraRight * Wnear);

  ftl = fc + (cameraUp * Hfar) - (cameraRight * Wfar);
  ftr = fc + (cameraUp * Hfar) + (cameraRight * Wfar);
  fbl = fc - (cameraUp * Hfar) - (cameraRight * Wfar);
  fbr = fc - (cameraUp * Hfar) + (cameraRight * Wfar);

  // Computation of the 6 frustum planes
  topPlane = {ntr,ntl,ftl};
  bottomPlane = {nbl,nbr,fbr};
  leftPlane = {ntl,nbl,fbl};
  rightPlane = {nbr,ntr,fbr};
  nearPlane = {ntl,ntr,nbr};
  farPlane = {ftr,ftl,fbl};