# Imaging and meshing integration

Milestone 06 owns the native implementations in `libremetaverse-imaging`,
`libremetaverse-imaging-skia`, and `libremetaverse-prim-mesher`. The core
imaging and meshing crates contain no CLR bridge, subprocess adapter, foreign
RPC, or generated failure-only shim. The rendering crates consume the checked
mesh data but remain a separate milestone: `SimpleRenderer` now provides the
reference prim/sculpt conversion pipeline. `MeshFoundry` now adds bounded mesh
asset, rigging, tangent, secondary-UV, terrain, and convex-hull handling without
changing the milestone 06 ownership boundary. See the
[`SimpleRenderer` guide](../crates/libremetaverse-rendering-simple/README.md)
and [`MeshFoundry` guide](../crates/libremetaverse-rendering-mesh-foundry/README.md).

## Feature boundary

| Surface | Default build | Opt-in build | Native dependency |
| --- | --- | --- | --- |
| Managed images and TGA | enabled | n/a | none |
| JPEG 2000 | disabled | `libremetaverse-imaging/jpeg2000` | OpenJPEG 2.5.x |
| BMP/GIF/ICO/JPEG/PNG/WBMP/WebP | disabled | `libremetaverse-imaging-skia/skia` | Skia |
| Prim and sculpt meshing, OBJ ingestion | enabled | n/a | none |

OpenJPEG is excluded from the default workspace and is reachable only through
the optional dependency. Skia is an optional, target-specific dependency;
Linux and Windows use the Vulkan-capable binary configuration while macOS uses
the corresponding non-Vulkan binary configuration. Dedicated workflows build
both optional features on Linux, macOS, and Windows. The default
`imaging-meshing` workflow proves that no native codec is needed for the owned
Rust and translated compatibility tests.

## Bounds and rendering contract

Decoded images are limited to 4,096 by 4,096 pixels and encoded inputs to 64
MiB. Channel sizes, resize products, codec buffers, sculpt-map dimensions,
profile/path sizes, mesh vertex counts, face indices, viewer groups, and OBJ
indices use checked arithmetic before allocation or indexing. Malformed input
returns a typed error.

The rendering-facing integration tests verify that PrimMesh and SculptMesh
produce finite positions, normals, and UVs; aligned face and viewer-face data;
preserved prim-face grouping; in-range indices; and the 16-bit index range used
by the pinned MeshFoundry reference at every supported sculpt topology and LOD.

## Reproducible gates

Run the fixed ownership and feature audit with:

```console
python3 tools/check_milestone_06.py
```

The audit rejects owned Rust stubs, feature leakage, missing platform jobs,
missing performance targets, or drift in the 48 reviewed ManagedImage,
Coord/Quat, and PrimMesh compatibility cases. The cross-platform workflow also
runs each reviewed group explicitly, native crate tests, workspace test
compilation, Clippy with warnings denied, rustdoc with warnings denied, and
benchmark compilation.

The focused performance baselines are executable Rust programs rather than
wall-clock assertions, so slower shared runners do not weaken or destabilize
correctness tests:

```console
cargo bench -p libremetaverse-imaging --bench image_pipeline
cargo bench -p libremetaverse-prim-mesher --bench meshing
```

The image baseline clones, bilinearly resizes, and exports a 2,048-square RGBA
image. The meshing baseline builds and indexes a high-detail cut, hollow,
twisted circular extrusion. Both report elapsed time and allocation counts so
regressions can be compared using the same inputs.