static private int first_node(float[] t0, float[] tm){
    float tmax = DwVec3.maxComponent(t0);
    if( t0[0] == tmax) return ((tm[1]<t0[0])?2:0) | ((tm[2]<t0[0])?1:0); // YZ:tx0=max
    if( t0[1] == tmax) return ((tm[0]<t0[1])?4:0) | ((tm[2]<t0[1])?1:0); // XZ:ty0=max
                       return ((tm[0]<t0[2])?4:0) | ((tm[1]<t0[2])?2:0); // XY:tz0=max
  }