protected final void addLineWithClip(int a, int b) {
    float az = vertices[a][VZ];
    float bz = vertices[b][VZ];
    if (az > cameraNear) {
      if (bz > cameraNear) {
        return;
      }
      int cb = interpolateClipVertex(a, b);
      addLineWithoutClip(cb, b);
      return;
    }
    else {
      if (bz <= cameraNear) {
        addLineWithoutClip(a, b);
        return;
      }
      int cb = interpolateClipVertex(a, b);
      addLineWithoutClip(a, cb);
      return;
    }
  }