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feat(codec): deserializePointCloudView — decode PJ.PointCloud without copying the points (0.35.0) - #201
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… copying the points (0.35.0) deserializePointCloud() copies the packed point bytes out of the wire buffer for every sample. deserializePointCloudView(data, size, anchor) points the cloud's `data` into the input instead and keeps it alive through the caller's BufferAnchor, like deserializeVideoFrameView. A null anchor copies, exactly as before. A new name rather than an overload: builtin_object_codec.cpp (and any consumer) takes the address of deserializePointCloud, which an overload would make ambiguous. Motivation (PJ4, Iris Xe): the host's per-sample copy of a 10M-point cloud costs a memmove plus ~29k first-touch page faults per frame; with the view the 10M stream frame went from 137 to 71 ms of wall time. MINOR: an additive client-side helper; host contract unchanged. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01V3ZZU95hWdyWcCj8dQkmAi
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Summary
PJ::deserializePointCloudView(data, size, BufferAnchor anchor)inpj_base/builtin/point_cloud_codec.hpp. It decodes a canonicalPJ.PointCloudwhile pointingdatainto the input buffer instead of copying it, and keeps that buffer alive through the caller's anchor. This mirrorsdeserializeVideoFrameView.deserializePointCloud(), which is unchanged.decodePointCloud, so validation and field handling are the same code path.builtin_object_codec.cpptakes&deserializePointCloud, and an overload would make that ambiguous, for consumers as well.Why
PJ4's host decodes every point-cloud sample from the ObjectStore, and that payload is already immutable and anchored. Measured on the PJ4 QRhi branch (Iris Xe, 5 interleaved rounds) with a local build of this change:
deserializePointCloud)deserializePointCloudView)At 300k points, GUI CPU goes from 1.73 to 1.36 ms.
Versioning
MINOR (0.35.0). This is an additive client-side helper: no host surface, no vtable or ABI change, and existing binaries are unaffected. The CHANGELOG records
Host contract: unchanged (no floor impact), andVERSIONis bumped.Test plan
point_cloud_codec_test: 7/7 pass, including 3 new tests:./build.sh --sdk-local: the point-cloud golden images are byte-identical.🤖 Generated with Claude Code
https://claude.ai/code/session_01V3ZZU95hWdyWcCj8dQkmAi