ACIS SAT entities (Solid3D / Region / Body) were tessellated at one
fixed sampling density (CIRC_SEGS=48, GRID_U=32, GRID_V=16) regardless
of how far they were from the camera. Distant solids paid the full
triangle bill for fragments that mostly resolved to sub-pixel size.
Generate three pre-built LODs per entity at load time:
* LOD 0 (HIGH) — 48/32/16 segments. Use above 200 px projected diag.
* LOD 1 (MID) — 24/16/8. Use 50–200 px.
* LOD 2 (LOW) — 12/8/4. Use below 50 px.
Tessellation cost is paid 3× on load (cheap — typical files have few
solids). Render picks per-frame via `compute_mesh_lod` from each mesh's
`world_aabb` projected diagonal. When a level is missing (e.g. a solid
entity that only emits LOD 0), the selector walks down to the nearest
available slot.
API ripples:
* New `LodConfig` (HIGH/MID/LOW) drives `tess_sat`, `tess_cone_face`,
`tess_sphere_face`, `tess_torus_face`.
* `tessellate_solid3d / _region / _body` now return `MeshLodSet`.
* `MeshLodSet { lods: Vec<MeshModel>, world_aabb }` + `from_single`
constructor so interactive truck-based commands (BOX/CYLINDER/etc.)
that only generate one tessellation stay one-line.
* GPU side gets `MeshLodGpu { lods: Vec<MeshGpu>, world_aabb }` and
a `mesh_lod_levels` per-frame index vector.
* STL/STEP export pulls slot 0 explicitly so the on-disk geometry
isn't downgraded by the view-dependent ladder.
Background-thread lazy generation (per the roadmap) is deferred — the
synchronous eager build is fine for typical CAD files. Switch to a
queue + background tessellator when files with hundreds of solids
become a load-time bottleneck.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
LwPolyline PLINEGEN=0 (DXF default): emit SegmentedLines with NaN
separators between vertex-to-vertex segments; wire_gpu resets
arc-length to 0 after each NaN so linetype pattern restarts per vertex.
PLINEGEN=1: existing Contour path unchanged (continuous pattern).
WireModel gains plinegen field propagated through tessellate pipeline.
Solid3D/Region/Body: call SabReader::read() when parse_sat() returns
None due to binary SAB format (DWG files / newer AutoCAD exports).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Refactors solid3d_tess to share tessellate_sat() across Solid3D,
Region (2D planar ACIS body), and Body (3D ACIS body).
populate_meshes_from_document() and add_entity() now tessellate
all three entity types into GPU MeshModels when ACIS SAT data
is available.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
