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Look how far Shrek has come in a decade: From a simple green ogre to a thing of beauty in Shrek Forever After, the fourth and final installment in the phenomenally popular DreamWorks Animation franchise (opening Friday through Paramount ).

Thanks to technological advances at PDI/DreamWorks in Redwood City and the DreamWorks Animation campus in Glendale (where Forever After was made to inject fresh blood), Shrek has continued to raise the bar in CG character animation and simulation for hair, fur, cloth, fire, water and global illumination.

Just think: there were 600+ character controls in Shrek compared to nearly 850 for Shrek 2, 1,083 for Shrek the Third and more than 1,200 for Forever After.

"There has always been the Shrek path of doing things and then all of the other shows, so one of the key things I did early on with rigging was add more squash-and-stretch to give it more life and make the characters seem less like puppets," explains Jason Reisig, head of character animation on the fourth Shrek. 

"We retrofitted the Shrek characters to have the new skeletal structure that we've been developing, which allowed the characters to be looser and more expressive and more natural. Shrek's spine had always been very rigid and when he's flying around the broom chase, he gets into stretched out poses for the first time. But you have to be careful with Shrek's face because it looks weird and goes off model quickly. However, with Rumpelstiltskin, there were no barriers: he's an exaggerated personality."

According to Darin Grant, head of production technology, there's an ear trumpeting gag introduced by Shrek and the other ogres that never could've previously been done as a result of the retrofitting. "There's a line, 'I didn't know we could do that,' which turns out to be true because on Shrek his ears had to be individually animated, and then on Shrek 3 we developed some secondary motion systems to allow the ear movement to be more simulated based on head movement."

Meanwhile, Puss in Boots has three rigs in Forever After: one for the normal Puss, another for the fat Puss in the alternate reality that Shrek has been tricked into experiencing and a bi/quadped so he can go from one stance to the other.

Speaking of the swashbuckling feline, who has his own Sergio Leone-inspired animated feature next year, he required an upgrade in the fur shader for his introduction in Shrek 2. Not only that but there were two shaders for the feather plume in his hat and a new simulation system for automatically getting the cat's fur out of the way of his belt, which was hand-animated.