Implement LCC and SPZ encoding pipelines with comprehensive tests#7
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Implement the inverse of the LCC reader — encoding DataTable columns into the LCC binary format (data.bin, shcoef.bin, index.bin, meta.lcc). New files: - src/io/lcc_encoder.h/.cpp — encode functions (rotation 10-10-10-2, color RGBA, scale exp→uint16, SH 11-10-11, full 32-byte splat record) - include/splat/io/lcc_writer.h — public API (LccWriteConfig, writeLcc) - src/io/lcc_writer.cpp — full pipeline: range collection, quadtree spatial partition, per-cell encoding, file output with nlohmann::json - tests/lcc_writer_test.cpp — 12 round-trip tests for all encoders Fixes: - cmake/FindWebP.cmake: add libsharpyuv for WebP 1.4+ compatibility - lccClamp: fix inverted upper-bound ternary (returned x instead of hi) Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
- Extract shared decode helpers (decodePositions/Scales/Colors/Alphas/Rotations/SH) for reuse across legacy v2-v3 and v4 NGSP paths - Add NgspFileHeader struct, TOC parser, and ZSTD stream decompressor - Implement readSpzV4: parse 32-byte header, ZSTD decompress per-stream, decode attributes via shared helpers, build DataTable - Modify readSpz to detect v4 NGSP magic (0x5053474E) and dispatch - Legacy v2-v3 GZip path preserved unchanged via readSpzLegacy Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
- spz_encoder.h/.cpp: encodePosition (int24), encodeScale (log->uint8), encodeColor (SH DC->uint8), encodeAlpha (sigmoid->uint8), encodeRotation (smallest-three 9-bit packing), encodeSH (bucket quantize) - spz_writer.h/.cpp: DataTable -> per-splat encode -> ZSTD multi-stream compression -> NgspFileHeader + TOC -> .spz v4 file output - Configurable SH quantization via SpzWriteOptions (sh1Bits/shRestBits) Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Iter 2 (Writer): - spz_writer_test.cpp: round-trip tests (no SH, with SH, single splat) Iter 3 (CoordinateConverter): - include/splat/maths/coordinate-converter.h: 16-system enum, converter struct - src/maths/coordinate-converter.cpp: within-family sign flips, cross-family R_x(±π/2) analytic rotation for pos/quat/SH bands 0-1 - coordinate_converter_test.cpp: identity, within-family, cross-family round-trip, all 16 systems Fix: add missing <cmath> include in spz_encoder.h for std::exp Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Covers v4 NGSP (ZSTD multi-stream) and v2-v3 legacy (GZip) formats: - File layout with header, TOC, attribute stream ordering - Per-attribute encoding formulas: position (int24), scale (log), color (SH DC), alpha (sigmoid), rotation (smallest-three), spherical harmonics (bucket quantization) - Coordinate system conventions (RUB default) - File detection logic - References to the official SPZ repository Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Reader: - Lcc2Scene/Lcc2Node data structures (Eigen bounding box, optional 3dgs/mesh refs) - JSON tree parse with recursive node builder - Format dispatch by file extension (PLY/SPZ/SOG via existing readers) - Lazy loading with file-index cache - flattenLcc2Scene: collect all leaf data + concatenate Writer: - Quadtree spatial partition (reused from LCC1) - Per-cell SPZ file output via writeSpz - Two-level JSON tree: root → cell nodes → LOD leaves - Auto GUID generation, configurable cell size and output name ~380 lines total (vs LCC1's ~1200). LCC2 delegates encoding to standard formats — no custom binary codec needed. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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