fullseye

geodesic_dome — 3D polyhedron op

使い方

Geodesic sphere from a subdivided icosahedron — Euler decides the shape.

Each icosahedron face is cut into frequency**2 triangles and every vertex is pushed out to the sphere. The counts are then forced, not chosen: F = 20*f**2, E = 30*f**2, V = 10*f**2 + 2, and Euler’s formula V - E + F == 2 holds exactly.

★Why this earns its place: Euler also forces the irregularity. If every vertex had degree 6 then 2E = 6V, which contradicts V - E + F = 2; counting degrees gives sum(6 - deg(v)) == 12 over all vertices, so a triangulated sphere built from hexagons must contain exactly twelve pentagons — no more, no fewer, at any frequency. That is why a football has twelve black patches, and it is an integer this operator must reproduce exactly. Nothing about the drawing can be “close enough”.

Returns a mesh (V, F): V is (n, 3) float, F is (m, 3) int. With hemisphere=True the vertices below z = 0 and the faces touching them are dropped (then Euler no longer gives 2, and the twelve-pentagon count applies to the full sphere only — said here rather than letting the gate quietly change meaning).

Raises ValueError: frequency < 1; radius <= 0; the mesh would exceed the cap.

HALCON: no operator (gen_sphere_object_model_3d makes a UV sphere, whose poles are degenerate — a different object).

参考(サンプルデータ・文献)

実行できる例(この op を実際に呼ぶ検証済みサンプル)

型が繋がる次の op(mesh を入力に取れる)

mesh_to_voxel · mesh_to_points · to_points · fuse_to_voxel · ambient_occlusion · cast_shadow · supersample_mesh · render_beauty

同カテゴリ(polyhedron)

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Provenance: render3d.py — 3D operator registry. この per-op ノートは tools/opdocs.py md が自動生成(手編集しない)。

© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.