🕯️ Cast Shadow

$ man cast-shadow

The stick's shadow is the given — your ruler. The stick is 1 tall, and its shadow shows two things: which way the light throws a shadow, and how far one stick-height of shadow reaches. The sun is at infinity, so the arrows at the frame edge are the whole story: every ray runs that same direction, and the reach grows in step with height. A corner twice as tall as the stick throws its shadow twice as far. Do not copy the ruler's length — count in rulers.

Run one ray per corner: press a numbered top corner (near enough counts — it snaps) and pull down to where its shadow lands. A press on its own only picks the corner; the ray is run once you drag, so you can look before you commit. While you drag, the sheet says how long your ray is in rulers (“×1.8 the ruler”), and the hint says how many rulers tall that corner is. Four rays, then done — and the true shadow inks itself in amber over yours, with a dotted hop from each of your landings to its true one. The line under the score says whether you ran the rule: first whether the rays went the ruler's way at all, then whether they reached far enough.

From item 2 the top is a slope, so the four corners sit at four different heights and each ray is its own length — the hint says so when it happens. Numbers pair a corner with its landing; that pairing is what the score compares.

Keys: 1–4 pick a corner · arrows run and nudge its landing (shift for bigger steps) · Enter done, then next, then new round.

Scored on how close each landing sits to its true one. What is forgiven before the score starts falling is set for the hardware you are on — the HUD says which (pen, mouse or trackpad, finger) — and it never falls below a few real pixels, so a small phone sheet is not judged more harshly than a desktop one. Studio tip: a cast shadow is not a smudge — it is where each corner's light ray hits the floor, so run the rays first and connect the landings after.