code: public void setOuterConeAngle(float angle)
      {
          setFloat("outer_cone_angle", (float) Math.cos(Math.toRadians(angle)));
          mChanged.set(true);
      }
docs: Set the inner angle of the spotlight cone in degrees.
  
  Beyond the outer cone angle there is no illumination.
  The underlying uniform "outer_cone_angle" is the cosine
  of this input angle. If the inner cone angle is larger than the outer cone angle
  there will be unexpected results.
  @see #setInnerConeAngle(float)
  @see #getOuterConeAngle()