* @param matrix target object for the new matrix
   */
  protected void splineForward(int segments, PMatrix3D matrix) {
    float f  = 1.0f / segments;
    float ff = f * f;
    float fff = ff * f;

    matrix.set(0,     0,    0, 1,
               fff,   ff,   f, 0,
               6*fff, 2*ff, 0, 0,
               6*fff, 0,    0, 0);
  }