viewport — GFX2D camera op

• Data kinds: rgb → rgb

• Call: import gfx2d; gfx2d.viewport(img, x, y, width, height, scale=1.0, interp='bilinear') (or opsgfx2d.get("viewport"))

Usage

Crop the rectangle at `(x, y, width, height) and resample it by scale`.

Accepts `rgb or rgba` (straight alpha; the crop is a copy, so no

premultiplication is involved) and returns the same channel count.

Out-of-bounds raises, unlike :func:sprite_blit, which clips. The

asymmetry is the point: a sprite leaving the screen is the normal case,

while a camera asking for rows the image does not have is arithmetic that

has already gone wrong somewhere upstream, and returning a partly black

frame would let it keep going.

`scale=1` with integer bounds returns an exact sub-array copy — no

interpolation touches it.

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.

• The canonical algorithm (author, year) and its uses are named in the family usage guide above.

Runnable examples (verified samples that actually call this op)

• gfx2d_scene — py -3.11 examples/gfx2d_scene.py

Ops the type connects to (they accept rgb as input)

srgb_to_linear · linear_to_srgb · blend_mode · light_mask · normal_map_decode · bloom · vignette · chromatic_aberration

Same category (camera)

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*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.