The “think slow” part of Pixar planning, David Epstein explains (in Inside the Box), started before Pixar even existed:
Catmull was surprised then, in 1980, when a Lucasfilm competitor spent $10 million on a Cray-1 supercomputer. He and his colleagues wondered if they should chase that competitor, so they sat down and made specific estimates for the computing power it would take to animate an entire film. Their estimate: It would take one hundred Cray-1 computers, which would cost $1 billion. Totally out of the question. “It was like, OK, they’ve just done something unwise economically,” Catmull told me. “So we decided we’re not going to worry about them, and there are a whole bunch of other things we have to solve first.”
[…]
At one point, they calculated the exact number of pixels (five million) and “micropolygons” (eighty million) that they figured software would need to render in order to make a Star Wars quality sequence, down to the realistic blur of speeding objects. Like the summaries in By Space Ship to the Moon, the estimates were guiding lights that helped them keep track of the distance between their current work and their goal.
[…]
In 1988, Pixar released its RenderMan software, and changed filmmaking forever. It was used to seamlessly integrate computer graphics into live-action films like Terminator 2 and Jurassic Park. And then, in 1995, to create an entire film: Toy Story. After twenty years of small steps, Catmull finally achieved his personal moonshot.
The Last Starfighter came out in 1984, well before then:
Computer graphics for the film were rendered by Digital Productions (DP) on a Cray X-MP supercomputer. The company created 27 minutes of effects for the film. This was considered an enormous amount of computer generated imagery at the time.[6] For the 300 scenes containing computer graphics in the film, each frame of the animation contained an average of 250,000 polygons and had a resolution of 3000 × 5000 36-bit pixels. Digital Productions estimated that using computer animation required only half the time and between a third to half of the cost of traditional special effects. The result was a cost of $14 million for a film that made close to $29 million at the box office.
The computer graphics are quaint: