To determine the gown's volume, fullness and where certain areas would rest on the character's form, the costume designer worked with both a pattern maker and designer. The patterns and seams were labeled and forwarded to the animators, who would replicate the images on the computer. Mussenden decided to give Fiona's dresses tight sleeves as opposed to the long, flowing sleeves associated with traditional medieval clothing due to the difficulty the latter would have been for the animators. Unlike "Shrek", Fiona has several costume changes in "Shrek 2". In the sequel, both Fiona's ogre and human forms are shown wearing the same green dress. To ensure that both forms looked equally flattering in the same outfit, Mussenden lowered the dress' waistline to make it more medieval in appearance than the costume she wears in the first film. Fiona's first costume is a lilac dress, which Mussenden designed to appear "organic and textured, because she's been living in the swamp". Towards the end of the film, she changes into a white ballgown with rhinestones inspired by an image of a 1958 dress the costume designer had found. The scene in which Fiona single-handedly defeats Monsieur Hood and his Merry Men references the slow motion special effects popularized by "The Matrix" (1999), as well as Diaz's own "Charlie's Angels" films. In a DVD bonus feature, Fiona explains that she performed her own stunts in the film, claiming that she based her kung fu on "Charlie's Angels". Despite concerns that references to "The Matrix" would eventually date the film, Rossio believes the gag will remain funny because it is a parody instead of merely an imitation. A similar reference is made when Fiona defeats a mob at the beginning of "Shrek 2", a complex sequence for which animators used powerful data processors to store and manipulate millions of computer generated images. Modesto created new character models for Fiona and Shrek in "Shrek the Third", while new software and servers were implemented to animate individual strands of the princess's hair much faster than had been possible during production of the first film. In "Shrek Forever After"'s alternate reality, the character wears her hair unbraided for the first time, which was inspired by singer Janis Joplin. Due to its costliness, Fiona's new hairstyle first needed to be approved by DreamWorks, with Mitchell likening the process to "prepar[ing] like a lawyer". The re-design was a difficult, expensive process that required 20 animators to animate each strand individually, as Mitchell was particularly determined to render it correctly due to audiences' familiarity with long hair.