v1.2.3

The high-severity findings from the hard-coded values audit (issue #136), plus #134 and #135.

Fixed

• Shadows on transformed bodies (#136, H2). The shaded fragment applied body.transform a second
  time before the shadow-map lookup, so any body with a non-identity transform sampled the shadow map
  in the wrong place. Transformed receivers now shadow exactly like the same geometry baked into vertices.
• Section clip planes apply everywhere (#136, H3). Clip planes were ignored by GPU picking, the
  SSAO/silhouette depth prepass, the selection outline and point clouds.
  • Clicking a sectioned model now picks the visible geometry, not the clipped-away body in front of it.
    This covers faces, edges, arcs and vertices on the standard, tessellated and mesh-shader paths.
  • Silhouettes and SSAO no longer outline or darken around removed geometry.
  • The outline is cut exactly where the section cuts the body.
  • Point clouds are sectioned.
• Pick ID limits are guarded (#136, H4). Picks pack a 16-bit body index and a 14-bit primitive index
  into one R32Uint.
  • Beyond 65,536 visible bodies, later bodies used to corrupt other bodies' picks; they now read back
    as a miss.
  • On a body with more than 16,384 primitives of the picked kind, the index used to wrap silently.
    Tap picks and tap-to-measure now resolve wrapped face indices with a CPU ray test, and every
    result carries isPrimitiveIndexAmbiguous.
• Direct-mesh selection (#136, H5). Selecting or hovering a ViewportBody.directMesh(...) body, or
  giving it triangleStyles, drew garbage. The outline and highlight passes now have direct-mesh
  pipelines.
• Face picks at higher rendering quality (#136, H7 and L10). Under .enhanced, the tessellated pick
  reported the B-Rep face index instead of the triangle index. Under .maximum on Apple9 GPUs, the
  mesh-shader pick reported a meshlet-local index (0-63). Both now report the global triangle index, so
  faceIndices[triangleIndex] lookups and tap-to-measure work at every quality level.
• Tap-to-measure on direct-mesh bodies. worldHitPoint(ray:triangleIndex:) returned nil for them.
• OffscreenRenderOptions.msaaSampleCount is honoured (issue #134). OffscreenRenderer built every
  main-pass pipeline for a hard-coded 4 samples and always made multisample textures. A count of 1,
  documented as "disabled", aborted on Metal validation (sampleCount must be > 1 for multisample textures), and any count other than 4 mismatched the pipelines. Pipelines are now built per sample
  count and cached (4 at init, others on first use). A count of 1 draws straight into the readback
  texture, and unsupported counts round down to one the device supports.
• Edges no longer disappear when they lie in front of the mesh (issue #135). ViewportBody.boundingBox
  only covered mesh positions, but both renderers fit the near clip plane to it (since #116), so an
  edge nearer the camera than its body's mesh was clipped. It now includes every edges point and the
  full circle of every arcs entry (conservative for partial arcs).
  The same box also drives frustum culling, shadow framing and CameraState.fit(to:). Edge-only
  bodies (wires, sketches) used to have no bounds, so they were never culled and fit-to-view ignored
  them; both now work for them.
• Dash patterns now apply to edge-only bodies (wires, sketches, sampled curves). The quad edge
  fragment shader returned the body colour for them before reaching the dash test, so they always drew
  solid; v1.2.2 documented this as a limitation. The dash test now runs first for every edge.

Added

• PickResult.isPrimitiveIndexAmbiguous, PickResult.maxPickableBodies (65,536) and
  PickResult.maxPrimitivesPerKind (16,384). The limits are documented in the Picking reference and
  cookbook.
• ViewportBody.resolveWrappedTriangleIndex(_:ray:) resolves a wrapped face-pick index with a CPU ray
  test.
• PickResult.init(rawValue:indexMap:layerMap:ambiguousKinds:). The new parameter is optional, so
  existing call sites are unaffected.

Changed

• Tap picks and tap-to-measure resolve wrapped face indices before publishing pickResult or adding a
  measurement point. A face tap that can't be resolved on such a body adds no measurement point.
• The neighborhood pick behind PickingConfiguration.pickRadius (#118) is split into two pure functions,
  clampPickNeighborhood and bestNeighborhoodPickResult, as performRegionPick already was. No
  behaviour change.

Tests

• ShadowTransformTests (new): a transformed caster and receiver shadow identically to the same geometry
  baked into vertices (H2).
• ClipPlanePassTests (new): headless ViewportRenderer tests for clip planes in the pick, point-cloud,
  selection-outline and SSAO/silhouette passes (H3).
• PickEncodingLimitsTests (new): object-index guard, wrap detection and resolution, and headless GPU
  checks that the tessellated and mesh-shader pick paths report input triangle indices (H4, H7).
• DirectMeshSelectionTests (new): selection outline, hover outline and triangleStyles match between
  interleaved and direct-mesh builds of the same sphere (H5).
• OffscreenSampleCountTests (new): sample-count mapping, and a render at 1, 2, 4 and 8 samples on one
  renderer (#134).
• BoundingBoxTests: six cases for #135 (edge-only bounds, edges extending a mesh, arc-only and tilted
  arc bounds, direct-mesh bounds, and the near plane covering an edge in front of the mesh).
  EdgeDashRenderingTests now puts its line in front of the mesh, with a solid-edge case that rendered
  nothing before the fix.
• NeighborhoodPickTests (new, 14 cases): clamping at texture edges, and best-hit selection (vertex over
  edge over face, nearest of the same kind, 2D distance, ties, unknown bodies, layer map).
• EdgeDashRenderingTests (new, 3 cases): headless renders counting dashes along a line, for an
  edge-only body and a meshed body. The edge-only case fails against the v1.2.2 shader.