Issue link: https://digital.copcomm.com/i/77744
n n n n CG Animation stead, we faked the occlusion and shadowing. Instead of casting rays, I took the procedural signal, all the formulas and the fractals, and generated occlusion and shadows myself. That way, all the vegetation responded to lighting in a predictable way." For example, when the code would create a clump of grass, Quilez darkened the blades in the center manually. Similarly, if a tree canopy had a key light on the left, rather than light- ing the left side and darkening the right with shadow maps or deep shadows, he faked the lighting with instructions in the code. Magician at Work "The process would be like this," Quilez says. "A tree trunk gets rendered. It calls the code that grows the leaves. The leaves grow with a shader attached that generates the color, the same as for anything, and passes it to the lighting. But, some of the coloring and light- ing decisions are in the code. The code doesn't apply them; the decision about what is dark and light just passes down the pipeline to the shader and lighting tool." When vegetation needed to interact with characters, Quilez hand-coded the animation, too. "Because we didn't have data on disk, there was nothing to simulate," he says. "So instead, I told the code where the interaction would hap- pen by putting in spheres that defined a radius. Then we had parameters we could tweak to move the blades of grass inside the sphere." The parameters would specify when the blades bent, by how much, and how long it would take to bend and bounce back. "It wasn't that difficult to hand-code the animation," Quilez says. "I had three or four numbers to 14 June/July 2012 change and everything happened automatically. Because things ran fast, we could iterate fast." Quilez also paid attention to level of detail. To reduce the computing load, grass and other vegetation far from camera would grow with fewer curves and less detail. "In the end, we could render all the sets, which are quite com- plex, in less than 2gb," he says. When Quilez showed his idea to other peo- ple at Pixar, some told him he was, in effect, moving backward; that this was how people did things in the old days before artist-friendly tools, back when programmers had to write code to create images. Quilez disagrees with the notion that he's reverting to old-school days. "You always think of CG as moving for- Pixar implemented a completely new animation system to produce and perform Fergus, Elinor, Merida, and the other characters in Brave. Dubbed "Presto," the new system encompasses character rigging, animation, layout, and simulation. ward," Quilez says. "But, it's more like a spiral. We have faster computers now. And this was super fun. It was a dream. I love math, and to have a chance to use math to make images and beautiful movies was super cool." For her part, Kratter, the shading art director, has her own opinion of Quilez and his work. "When I first came back from Scotland and said I wanted a dense layering of lichen, grass, and moss, I was told it would be too expensive. But, Inigo [Quilez] spent six months working on his code, maybe more, and it was like he gave us a secret present. We had moss blanket- ing everything. We called him the wizard." Presto, Rig-o This living backdrop, as Wise describes the landscape, is primarily Merida's world, a lush, green world. In the beginning of the story, we see her as a child picnicking with her parents in the woods, but usually when she's outdoors, she's alone. There are two exceptions—when she visits the witch and when her mother changes. But otherwise, when she's with other characters—her parents, her wild little triplet brothers, the three clan lords, the dozens and dozens of rowdy clan members—we see them in and around the castle. All these characters were rigged, animated, and simulated through an entirely new proprie- tary system first implemented for Brave. Named Presto, the system replaces Pixar's previous char- acter pipeline, which was known internally as MenV (2x), and which included the studio's proprietary animation system, Geppetto. Modelers at Pixar work primarily in Auto- desk's Maya. Presto takes over from there and encompasses character rigging, animation, lay- out, and character simulation. Cached scenes go from Presto to lighting and effects. Character supervisor Bill Sheffler began working on the new system in 2007 when Ratatouille wrapped. "A code base over 20 years old or so can reach an end of life," he says. "You can't make big changes and push yourself further. We kept the best workflows, but this is a first-rate new code base for us to expand on. The big benefit is that our IK sys- tems are better, sculpting and weighting tools are better, and we can do better layering, ref- erencing, and class structures within the rigs. And, it's more WYSIWYG." Some of the major changes affected the way in which the technical directors rigged charac- ters. "In the past, we would weight and sculpt