Shade, Sheen and Feather

Shade went first, laying out the palette ramp — because you cannot show roundness with a single color; you need a range from dark to light.

"Here's my ramp," said Shade, setting out a strip of grays: a deep dark, a medium, a light, a near-white — a small handful of colors arranged darkest to lightest. "Just a few. You don't need dozens — a good ramp is a small set, spaced evenly from shadow to highlight." Shade held up the strip. "One flat color can only ever say 'flat.' But a ramp — a range of shades from dark to light — is the raw material of roundness, because a round thing is darker where it curves away and lighter where it faces you. I don't place them yet — that's Sheen's job. I just build the palette: the vocabulary of light and dark that the whole illusion will be spoken in. Get the ramp right — evenly spaced, not too many, dark enough dark and light enough light — and you've laid the foundation. Everything else is just knowing where to put each shade."

Then Sheen pointed up and to the left, and the flat circle popped into a ball — because roundness is really just shading to a light source.

"Now the magic," said Sheen. "I decide where the light comes from — let's say up and to the left, like an afternoon sun. And then I just... obey it." Sheen placed the ramp's colors according to that one decision: the lightest shade on the upper-left, where the imaginary sun would hit; the mid-tones curving around; the darkest shade on the lower-right, curving away into shadow; and a tiny near-white highlight dot right where the light would gleam brightest. And the flat gray circle stopped being flat. It rounded. It became a ball, solid and lit, sitting there on the grid. "That's it! That's the whole trick," said Sheen. "Pick a light source — commit to it — and then put the bright shades where the light hits and the dark shades where it doesn't. Suddenly a flat shape has form. And the secret is consistency: every part of the picture has to be lit by the same sun. Once you decide where the light comes from and shade everything to match, flat squares turn solid before your eyes."

And then Feather stepped in for the finishing touch — softening the harsh, jagged, stair-stepped edges with a few clever in-between pixels.

"Look at the edge of the ball," said Feather. "Where the curve goes diagonal, the pixels make an ugly staircase — jaggy, harsh, obviously made of squares." Feather peered close. "So along that jagged edge, I place a few pixels of an in-between color — a shade halfway between the ball and the background — right in the stair-step corners." Feather dabbed the in-between pixels into the jagged spots. "And now the eye, from a normal distance, blends them — the staircase softens into a smooth curve. That's anti-aliasing: a handful of in-between pixels that trick the eye into seeing a smooth edge where there's really a jagged one." Feather stepped back. "It's the smallest touch of all — just a few pixels — and it's what separates a rough sprite from a clean, professional one. The eye doesn't see the individual squares anymore. It sees a smooth, round, solid ball. And it never suspects it's really just a careful little grid of squares."