code: public void setFrustum(float[] frustum)
      {
          Matrix4f projMatrix = new Matrix4f();
          projMatrix.setFrustum(frustum[0], frustum[3], frustum[1], frustum[4], frustum[2], frustum[5]);
          setFrustum(projMatrix);
      }
docs: Set the view frustum to pick against from the minimum and maximum corners.
  The viewpoint of the frustum is the center of the scene object
  the picker is attached to. The view direction is the forward
  direction of that scene object. The frustum will pick what a camera
  attached to the scene object with that view frustum would see.
  If the frustum is not attached to a scene object, it defaults to
  the view frustum of the main camera of the scene.
  
  @param frustum array of 6 floats as follows:
  frustum[0] = left corner of frustum
  frustum[1] = bottom corner of frustum
  frustum[2] = front corner of frustum (near plane)
  frustum[3] = right corner of frustum
  frustum[4] = top corner of frustum
  frustum[5 = back corner of frustum (far plane)