В журнале Computer Graphics World (Апрель 2001 года) читаем:
For character creation and animation, PDI relies almost exclusively on its proprietary software tools, which have evolved during the 20 years the studio has been working with 3D animation. For Shrek, various teams developed new tools for that proprietary system in nearly every area-the underlying animation system, character set-up, cloth simulation, methods for creating crowds, and the rendering of skin, hair, and fur.
В той же статье написано, что симуляция ткани сделана в Мауа и экспортирована для рендеринга в виде набора объектов для каждого кадра.
Softimage, конечно, отличная программа, но к Шреку, по-видимому, отношения не имеет.