(a) A person commits an offense if he exposes his anus or any part of his genitals with intent to arouse or gratify the sexual desire of any person, and he is reckless about whether another is present who will be offended or alarmed by his act.
(b) An offense under this section is a Class B misdemeanor, except that the offense is:
(1) a Class A misdemeanor if it is shown on the trial of the offense that the defendant has been previously convicted one time of an offense under this section;
(2) a state jail felony if it is shown on the trial of the offense that the defendant has been previously convicted two or more times of an offense under this section; or
(3) a felony of the third degree if the actor is civilly committed as a sexually violent predator under Chapter 841, Health and Safety Code.