v0.12.3

Features

• Transparent unstructured volume rendering: render all cells of a VolumeMeshData semi-transparently with interior scalar colormapping. Upload once with upload_projected_tet_mesh and reference each frame via TransparentVolumeMeshItem in SceneFrame. The density setting controls how opaque the volume appears per unit of ray path length. Supports hex, tet, pyramid, and wedge cells; works with clip planes and composites correctly against opaque geometry.
• Surface Line Integral Convolution (LIC): visualizes tangential vector fields on mesh surfaces as directional streamline patterns. Flow vectors are uploaded as per-vertex attributes on the mesh and referenced by name each frame. The advection uses a viewport-sized per-pixel noise texture so contrast is consistent regardless of zoom level or surface scale. Three controls: number of advection steps (streak length), step size in pixels, and modulation strength.
• Eye-Dome Lighting (EDL): depth-discontinuity shading in the tone-map composite. Pixels near depth edges are darkened in proportion to the local depth change, sharpening silhouettes and improving depth separation in point cloud and volume renders. Tunable radius and strength.
• Unlit material mode: set Material::unlit to skip all lighting and output raw base color directly. Works on both the direct and instanced draw paths.
• aabb_wireframe_polyline: builds the 12 edges of an AABB as a polyline item ready to push into a scene frame.
• Interactive 3D probe and region widgets in interaction::widgets:
  • LineProbeWidget: two draggable endpoints in world space. Exposes the current segment geometry each frame.
  • SphereWidget: draggable center point and radius handle. Can be pushed as a clip object or used purely as a measurement widget.
  • BoxWidget: draggable center and six independent face handles; each face handle resizes the box while keeping the opposite face fixed.
  • All widgets suppress orbit while a handle is being dragged, following the same convention as ManipulationController.

Performance

• Volume mesh boundary extraction is now significantly faster on large meshes. HashMap face deduplication is replaced with a sort + linear scan, and the entry generation, sort, and winding-correction steps are parallelized with rayon. Meshes below 1024 cells fall back to sequential execution automatically.
• Implicit surface marching (march_implicit_surface): pixel loop is now parallel via rayon with no coordination overhead per pixel.
• compute_tangents: Gram-Schmidt normalization is always parallel; the sdir/tdir accumulation phase uses a per-thread fold/reduce above 1024 triangles.
• extract_isosurface: uses Z-slab decomposition above 64x64x64 cells. Each slab runs in parallel with its own edge cache; outputs are concatenated with adjusted index offsets.

Fixes

• Fix EDL depth linearization
• Dense transparent geometry revealing the background: when enough transparent layers overlapped at a pixel, the OIT composite step incorrectly discarded those pixels, showing the background rather than the accumulated color. The bug was harmless for typical surface transparency (few stacked layers) but visible with volumetric rendering at higher density settings.