tile op• Data kinds: sprites → rgba
• Call: import gfx2d; gfx2d.parallax_layers(layers, camera_x, factors, camera_y=0.0, factors_y=None) (or opsgfx2d.get("parallax_layers"))
Scroll a set of `rgba` layers at different rates and composite them.
`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.
• 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.
• The canonical algorithm (author, year) and its uses are named in the family usage guide above.
• gfx2d_scene — py -3.11 examples/gfx2d_scene.py
rgba as input)premultiply · alpha_composite · sprite_blit · sprite_transform · sprite_sheet_slice · nine_slice
tile)*Provenance: gfx2d.py — GFX2D operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.