matcap_shade — 3D `render` op

• Data kinds: normalmap × image2d → image2d

• Call: import fullseye as fs; fs.ledger.matcap_shade(normals, matcap) -> 'np.ndarray' (to call the implementation directly, import render_shade; render_shade.matcap_shade(normals, matcap) -> 'np.ndarray'; from the registry, ops3d.get("matcap_shade"))

Usage

MatCap: map view-space normals onto a lit-sphere texture to transfer a material's look. → `(H, W[, C])`.

> The detailed description below is the original text — the summary and the headings are translated.

視空間の単位法線 `(nx, ny)([-1,1]`)をテクスチャ座標に写像し

(`u = (nx+1)/2, v = (1−ny)/2、行方向で y を反転)、matcap` 画像を

双線形補間 で引く。ライト計算をせず、球にライティングして撮った 1 枚の素材見えを

任意形状へそのまま貼れる(金属・粘土・トゥーンなど)。

`matcap` は正方に近い lit-sphere テクスチャ:

• グレースケール `(h, w) → 出力 (H, W)`

• カラー `(h, w, C)(C 任意) → 出力 (H, W, C)`

背景(長さ 0 の法線)は 0。テクスチャ座標は端でクランプ(球外縁の法線 `|(nx,ny)|→1` は

テクスチャ縁を指す)。

fail-closed: 形状不正・非有限・小さすぎる(`h,w < 2)テクスチャは ValueError`。

Background guides (the physics and conventions behind this op)

• blender_interop — Blender との併用 — 形を作って fullseye で測る(軸・単位・正解データの罠)

References (sample data, literature)

• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).

• Operator provenance and references — the sources of the research/methods this op family came from.

Runnable examples (verified samples that actually call this op)

• render_shade — py -3.11 examples_3d/render_shade.py

Ops the type connects to (they accept `image2d` as input)

fuse_to_voxel · fit_poly_surface · eval_poly_surface · surface_form_error · background_flatten · polar_unwrap · fit_zernike · antialias

Same category (`render`)

project_points · render_point_depth · render_volume_projection · render_shaded · ambient_occlusion · cast_shadow · phong_shade · supersample_mesh

*Provenance: render_shade.py — 3D operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

matcap_shade — 3D render op