In the movie ';Watchmen';, why does Rorschach' mask move around in different patterns?

I just watched this movie last night and either I missed the explanation or they didn't explain why. Anybody know?In the movie ';Watchmen';, why does Rorschach' mask move around in different patterns?
In the comic book, it says that when Walter Kovacs was a dressmaker, he had to make a dress that contained shifting material based off a design by Doctor Manhattan. The woman didn't want the dress anymore so he kept it and made it into a mask.In the movie ';Watchmen';, why does Rorschach' mask move around in different patterns?
Well, first they represent the ink blot test he is named after (Rorschach ink blot tests).


http://en.wikipedia.org/wiki/Rorschach_i鈥?/a>





Secondly, they also represent his ideology. He has a black and white view on morality, that never melds into shades of grey. ';There is good and there is evil and evil must be punished';. However, his moral compass has to constantly shift for the different situations he is in, to include all factors.





Walter Kovacs used to work making women's clothes long before he became Rorschach. A woman asked for a dress that has a shifting black and white pattern on it, and with Dr. Manhattan's help he created it. The woman thought the dress turned out ugly, and no longer wanted it, but Walter kept it. Well, turns out the woman, named Kitty Genovese, was soon after raped and killed in front of her home by a stranger (a real murder). It was reported that many people witnessed the event, and it caused an outcry against bystander apathy (although the bystander apathy part was over exaggerated; a few people heard the incident but no one could have realized what was going on). In the Watchmen story, this event inspired Walter to become a crime fighter, and he made a mask out of the dress.


http://en.wikipedia.org/wiki/Kitty_Genov鈥?/a>
That's where he gets his name from...the patterns shift like the images in Rorschach tests...what you see in his mask is interpreted differently depending on who is looking.
It's never mentioned. Same about how they have superpowers. (In the film that is)