Full section tool for the web viewport, with the gizmo + interaction shared with
desktop from one codebase.
- True-face surface pick. pickSurfaceAt had always ray-cast the instance AABB (to
skip a depth readback), so cuts sat in front of the real surface. The pick
fragment already computes the exact world_pos (it clips sections with it); now
it OUTPUTS it to a 3rd pick MRT (RGBA32F) that every pick path renders, and
pickSurfaceAt / pickSurfaceAtAsync read it back (decodeMappedPickPosition;
ray-AABB kept only as a fallback). The web async pick chains id -> normal ->
position spontaneous staging maps.
- Web tool: LMB drops a cut at the picked surface (LMB drag still orbits), K
toggles, Shift+K clears; oriented to the real MRT surface normal. Exports + a
Section / Clear cuts toolbar pair.
- Shared gizmo: lifted the section-gizmo renderer (SECTION_WGSL + thick-line AA +
quad+arrow VBO + pack + screen-space hit-test) out of the Qt-coupled
OverlayRenderer into a Qt-free SectionGizmoRenderer that ViewportCore::render
draws for BOTH desktop and web (both already render via render()). One identical
gizmo; OverlayRenderer's now-dead section code removed. Fixed 1 m size (matches
the desktop constant).
- Interaction (shared): hitTestSectionGizmo (SectionGizmoRenderer::hitTest) +
beginSectionDrag / updateSectionDrag / endSectionDrag live in ViewportCore.
Drag a gizmo arrow to slide the plane along its normal; Del/Backspace removes
the most recent cut. Desktop's ViewportWindow dropped its duplicate hit-test /
drag math + state and delegates to the core; web wires the same calls.
Tests: sectionPlaneCount add/clear/cap (Catch2, 125); web smoke "click a surface
cuts geometry, clear restores" exercises the shared gizmo + 3-MRT pick (11/11).
Desktop object-pick / marquee unaffected; BonsaiViewer builds.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Dion Moult