## 2. What option 17 shows

- **The bot is drawn once, off-screen, then sampled.** Every 2×2 block becomes a particle with a "home" position and its original colour. The eyes are particles too, dark ones.
- **Each particle is either flying free or springing home.** Breaking changes the forces; rebuilding switches every particle back to a spring pulling it home.
- **Four ways to break:**

| Mode | Forces | Look |
|---|---|---|
| Dust | Wind + swirling noise, a sweep starting from the left | Crumbles to rust-grey, drifts away |
| Explode | Outward burst + gravity + floor bounces | Scatters, rains down, piles up |
| Vortex | Spin + pull toward a ring radius | Tornado orbit |
| Sparks | Upward lift + noise, colour shifts to flame | Glowing embers; overlapping light adds up |

- **Rebuild runs bottom-up.** Each particle has a start delay based on its height. The base forms first and the eyes arrive last, so the face "reveals" itself.

## 3. Experiments

1. **While assembled, drag your finger across the bot.** You carve through it like sand, then it heals.
2. **Explode, then untick Auto.** Particles pile on the floor. Tap "Rebuild" whenever you like.
3. **Untick "Motion trails."** Motion loses its speed and flow. Trails come from fading the old frame instead of clearing it.
4. **Sparks.** Where particles overlap, the colour gets brighter instead of covering what's behind. That's how light, fire and magic effects are layered in games.

## 4. Less obvious details

- **The swirl is "curl noise."** Instead of random pushes, particles follow the rotation of a smooth noise field. Curl noise has no sinks or sources, so particles swirl without clumping together, a standard film-effects trick for smoke.
- **The dust sweep is directional on purpose.** Each particle waits its turn based on its horizontal position, so the disintegration travels across the body like a wave. Random timing looks like noise; a sweep looks like an event.
- **Springs make the rebuild feel magnetic.** Pull strength grows the longer a particle has been returning. Stragglers get yanked home, so the tail of the rebuild snaps shut instead of drifting in.
- **3,800 particles run on the CPU (central processor).** Film-quality versions run millions on the GPU (graphics chip). The logic is identical; only the count changes.

## Examples

**Life of one particle**
```
home (tx,ty, colour) ──► HOLD: spring to home + hop
        │ break
        ▼
   FREE: mode forces (wind / burst / spin / lift) + your finger
        │ rebuild (after delay by height)
        ▼
   RETURN: spring pull that strengthens over time ──► HOLD
```

**Sampling the bot**
```
off-screen 150×150 drawing          particles
  ░▒▓█▓▒░                              · · · · ·
 ▒▓██●██▓▒      every 2×2 block      · · ● · · ·
 ▓███████▓   ──► with alpha > 200 ──► · · · · · ·   ≈ 3,800
  ▒▓███▓▒       becomes 1 particle     · · · · ·
```

**Trails vs no trails**
```
no trails:   clear frame → draw        ●
trails:      frame × 0.72 → draw      ···●   (old positions fade out)
```