parallax_layers — GFX2D tile op

• データ種: sprites → rgba

• 呼び出し: import gfx2d; gfx2d.parallax_layers(layers, camera_x, factors, camera_y=0.0, factors_y=None) (または opsgfx2d.get("parallax_layers"))

使い方

`rgba` レイヤ群を別々の速さでスクロールさせて合成する。

> 以下の詳細説明は原文のままです —— 要約と見出しは訳出済み。

`layers[0]` is the farthest layer and is drawn first. Each layer is

shifted by `-round(camera_x * factors[i])` columns (and rows, if

`factors_y` is given) and wraps — a parallax backdrop is a loop, and

wrapping is what makes it one.

Shifts are rounded to whole pixels, so the scroll is a pure permutation: a

single layer shifted by exactly its own width comes back with its alpha

channel bit-identical and its colour identical wherever `alpha > 0`. (The

colour of *fully transparent* pixels is not preserved — compositing goes

through :func:premultiply, which zeroes it by definition. That is the

documented cost of the premultiplied round trip, not a bug in the scroll.)

Sub-pixel scrolling would resample every frame and accumulate blur, which is

why it is not offered here — put the fractional part in

:func:sprite_transform if you need it.

参考(サンプルデータ・文献)

• サンプルデータ カタログ(DL URL / ライセンス) — 2-D は skimage.data(BSD/public)+ 合成、3-D は実データ源(Stanford/PDS 等)の DL URL。

• 演算子の来歴・参考文献 — この op 族の元になった研究/手法の出典。

• アルゴリズムの正典(著者・年)と用途は上記ファミリ使い方ガイドに記載。

実行できる例(この op を実際に呼ぶ検証済みサンプル)

• gfx2d_scene — py -3.11 examples/gfx2d_scene.py

型が繋がる次の op(rgba を入力に取れる)

premultiply · alpha_composite · sprite_blit · sprite_transform · sprite_sheet_slice · nine_slice

同カテゴリ(tile)

tilemap_render

*Provenance: gfx2d.py — GFX2D 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.