Shading and light

One light source, stated up front — usually upper-left or upper-right. Every surface in the sprite is lit from that direction, in every frame of every animation. A sprite whose light drifts between frames looks like it is made of different materials each frame.

The difference between pixel art and a brightness slider:

• Shadows rotate toward the ambient — in practice, toward blue/purple — and lose a little saturation.
• Highlights rotate toward yellow/orange and gain a little saturation.

A red #c04030 shades to something like #8a2f45 (cooler), not #802b20 (the same hue, darker). The second one is the tell.

recolor op shade applies this rule; palette op ramp builds ramps that already obey it. Use them instead of picking darker hex values by hand.

1. Block in flat base colours per material. No shading at all yet.
2. Check the silhouette — see rules://03-silhouette-and-form.
3. One shadow step, on the side away from the light. Stop and look.
4. One light step, on the side facing it.
5. Only then consider a second shadow, a specular, or reflected light.

Most sprites are finished at step 4. Detail added before the form is right just makes the wrongness harder to see.

Dithering buys you an intermediate value you do not have colours for, and it adds texture. It is not free: at small sizes it reads as noise.

• Use it for large flat areas, skies, gradients on 32×32 and up.
• Avoid it on a 16×16 character; you do not have the pixels.
• Prefer ordered patterns (bayer4) over noise. Random dithering looks like dirt at low resolutions.
• Keep the two dithered colours adjacent in a ramp. Dithering between distant colours produces visible speckle.

draw op dither handles the pattern; you choose the two colours and the ratio.

Manual AA — placing one intermediate colour at a hard diagonal — is a legitimate technique on larger sprites. It is not the same as alpha blending.

Never leave semi-transparent pixels in pixel art. They come from soft brushes and non-integer resizes, and they make a sprite look blurry and impossible to palette swap. validate flags them.