code: public float getNearPlane() {
          if (nearPlane == -1) {
              // Recalculate the distance if the cache is invalid
              final Vector3f nearPos = vertices[0].add(vertices[2]).add(vertices[4]).add(vertices[6]).div(4);
              nearPlane = nearPos.sub(position).length();
          }
          return nearPlane;
      }
docs: Returns the near plane distance of the frustum.
  
  @return The near plane