Performance Sprite Region Read

Sprite rectangle pixel copies

Readable RGBA32 sprite queries now copy the selected rectangle from the base mip, rather than copying the entire texture. The intermediate pixel array holds only that rectangle. Pixel colours, alpha policy, pivots and units per pixel retain their existing meaning. The managed copy owns its pixels; changing it does not change the texture. Full-texture reads and other readable formats retain their existing conversion path.

Three fresh-process pairs on Windows x64 Unity 6000.6.7f1 Editor Mono measure the public alpha-mask and local-art-bounds APIs. Every input is fully opaque RGBA32. Each workload receives 64 warm calls, calibration to at least 20 ms and 21 raw rounds. The second pair reverses process order. Table medians are medians of the three process medians.

API and rectangle	Before median	After median	Paired after/before range
Mask, 16×16 in 1024×1024	3048.33 µs	4.08 µs	0.0009–0.0020
Mask, 256×256 in 1024×1024	4124.69 µs	418.16 µs	0.0975–0.1123
Mask, full 32×32 texture	10.28 µs	9.56 µs	0.4968–1.2739
Bounds, 16×16 in 1024×1024	3148.91 µs	3.60 µs	0.0007–0.0011
Bounds, 256×256 in 1024×1024	2693.38 µs	176.66 µs	0.0601–0.0714
Bounds, full 32×32 texture	4.41 µs	4.19 µs	0.8962–0.9728

Both subrectangle workloads improve in every pair. The small full-texture mask control varies, including one slower candidate process; it establishes no stable speed improvement. These observations cover texture retrieval and each public query, but exclude texture creation and sprite creation. They do not qualify Editor source-PNG decoding, other texture formats, packed sprites, IL2CPP or WebGL performance. They are not total allocation-byte measurements.

Four native storage regressions fail against the original implementation and pass against the candidate. They check returned array length, nonzero source offsets, base-mip selection, exact colours, pivot mapping and independence from the texture. Three other-format controls retain converted-pixel semantics. The focused native correctness cohort passes 186 cases without skips. Each accepted timing process passes its six cases, returns raw exit zero and reaches both output stream ends without a drain stop. Source hashes remain stable within each process. Loaded module identities and production assembly hashes distinguish the two variants.

The replay archive contains the two implementations, timing and correctness sources, all six complete NUnit trees, all 21-round output sets, process receipts, credential-checked logs, a hash inventory, analysis and the native controller. Its README records the base checkout and replay steps. The final XML-doc addition changes no executable statements in the measured reader. New replays receive their own source, assembly and process identities. A preliminary launch selected the normal Runtime assembly and ran zero cases; the runner rejected it and it contributes no accepted observation.