Shade a sprite

Flat shading — the same hue, darker — is the clearest signal that a sprite was made by moving a brightness slider. Real shading shifts hue.

The rule

• Shadows rotate toward blue/purple and desaturate slightly.
• Highlights rotate toward yellow/orange and saturate slightly.

recolor op shade implements this. Use it instead of choosing darker hex values yourself.

Procedure

1. Fix the light direction and state it. Upper-left is the safe default. It does not move again — not across the sprite, not across animation frames.
2. Confirm the flat art is right first. look op preview. Shading a bad silhouette wastes the effort.

3. One shadow step. Select the region away from the light, then:

   select op="rect" rect={…}
   recolor op="shade" amount=-0.2 selectionOnly=true

   Or draw the shadow shape directly with draw if it needs to follow a form the selection tools cannot describe.

4. Look. look op="preview". Does it read as volume, or as a stain? A shadow that follows the form's cross-section reads; one that follows the outline does not.
5. One light step, on the side facing the light: amount=0.2.
6. Look again. Most sprites are finished here.
7. Only if it needs it: a deep shadow (amount=-0.4) in occluded crevices, a specular highlight of one or two pixels on the hardest material, or reflected light — a faint cool step on the shadow side's outer edge, which makes metal read as metal.

Ramps

If you will shade a material more than once, put its ramp in the palette:

palette op="ramp" base="#c04030" steps=5

Then draw with ramp entries directly. Reuse the darkest step across materials — it ties a sprite together and costs no palette slots.

Dithering

Only on 32px+ and only in large flat areas. Use bayer4, keep the two colours adjacent in a ramp, and stop if it reads as noise. See rules://02-shading-and-light.

Checks

• Is the light in exactly one place?
• Do the shadows hue-shift, or are they the same hue darker?
• Any banding — long parallel stripes of adjacent steps?
• Any semi-transparent pixels? (validate will tell you.)

Related

rules://02-shading-and-light, rules://01-palette-and-color, rules://22-materials-hard, rules://23-materials-soft, rules://24-lighting-scenarios, rules://72-3d-forms.