# IconForge

Generates acdream's application icons into `assets/icons/`. Provenance,
palette, rights notes and the wiring live in
[`assets/icons/README.md`](../../assets/icons/README.md); this file covers how
the pipeline works.

```bash
py tools/IconForge/forge.py launcher   # procedural, no game data needed
py tools/IconForge/forge.py client     # needs a DAT export in work/
py tools/IconForge/forge.py all
```

## Modules

| File | Purpose |
|---|---|
| `render.py` | Software rasterizer: z-buffer, perspective camera, Lambert key/fill/rim, Blinn specular, bilinear texture sampling, matcap materials. |
| `smooth.py` | Crease-aware normal welding + PN-triangle tessellation. |
| `ring.py` | Forged 3-D ring and hook meshes, plus the chrome and verdigris matcaps. |
| `chisel.py` | Distance-transform bevelling: turns any 2-D mask into chiselled metal. |
| `ac_glyph.py` | The ring-and-crescent sigil geometry. |
| `compose.py` | Badging: fields, masks, drop shadows, contact sheets, size strips. |
| `launcher.py` | Portal vortex, placement helpers. |
| `forge.py` | Entry point. |

## The three techniques worth knowing

**PN-triangle tessellation** (`smooth.py`). The retail mosswart head is 104
triangles and renders faceted. Each flat triangle becomes a cubic Bézier patch
built from its own corner positions and normals, with quadratically interpolated
normals — so the silhouette genuinely rounds instead of merely shading smoothly.
It needs no mesh connectivity, which matters because UV seams would otherwise
pull apart. Normals are welded across coincident positions first, but only
within a crease angle, so ear fins and tusk edges stay sharp while the skull
rounds off.

**Matcaps** (`ring.py`). A Lambert rasterizer cannot produce chrome, because
chrome is almost entirely reflection and there is nothing here to reflect. A
matcap — one image of a lit sphere, sampled by the camera-space normal — is the
standard cheap stand-in for an environment map. The sharp horizon band in
`chrome_matcap` is what makes the eye read "metal" rather than "grey plastic".

**Distance-transform bevelling** (`chisel.py`). For flat shapes — the crescent,
the ring, letterforms — take the distance transform of the mask, treat
distance-to-edge as height, and derive normals from the height gradient. Shading
those through the *same* matcap the 3-D meshes use keeps everything lit by one
imaginary environment. The height field is blurred before differentiating:
without that, the medial axis of each stroke shows through as a hatched ridge.

## Gotchas

- **Creature poses need the MotionTable.** `Setup.PlacementFrames` has no
  upright pose for creatures; pass the weenie's MotionTable id to the exporter
  or every part stacks on the origin.
- **Build a mask and its decorations in one frame.** The crescent's barb and
  tail attach at cusp angles solved from the circle intersection. Rotating the
  crescent and the spikes separately mixes sign conventions and leaves the tail
  floating clear of the cusp.
- **The launcher path is deterministic** and must stay that way: it reproduces
  the committed PNGs byte-for-byte, which is what makes an accidental edit show
  up as a diff. No RNG without a fixed seed.