From “Toy Story” through “Toy Story 4,” Pixar has revolutionized animation in its nearly three decades of existence. Each new movie requires new technical innovations. “Monster’s Inc.” helped them create fur, “Ratatouille” helped them create wet fur, and “Finding Dory” led them to create an octopus from scratch. In “Toy Story 4,” which comes out June 21, they updated Bo Peep, created Forky, and made perhaps the most realistic-looking cat you’ll ever see in animated form.