Shape List: per-shape render mode (Solid / Wire / Mesh)

[trailcode]

Summary

Add a per-shape rendering mode in the Shape List, alongside the existing solid/wire toggle. Include a new mesh / triangulation preview mode that shows the tessellation (the dense line-grid look sometimes seen on OCCT 8 wasm) as an intentional display option.

Must work on all platforms (desktop OpenGL and Emscripten/WebGL), not wasm-only.

Motivation

Shape List today has a binary solid/wire checkbox (AIS_Shaded vs AIS_WireFrame). That is useful but coarse:

• Solid — Phong-shaded surfaces
• Wire — B-rep edges only
• Mesh (new) — triangulation / mesh edges visible (x-ray / analysis aesthetic)

The mesh look appeared accidentally during OCCT 8 wasm shaded-mode work and is visually distinct from wireframe. It should be a first-class, user-selectable mode.

UI proposal

Replace (or extend) the current solid/wire checkbox with a compact control per shape row, e.g.:

• Dropdown / combo with labels such as: Solid, Wire, Mesh
• Tooltip on (?) help explaining each mode
• Same row layout as today: name | visibility | render mode | material

Prefer a dropdown over a third checkbox — scales better if more modes are added later.

Behavior

Mode	Expected presentation
Solid	Current shaded (AIS_Shaded), no mesh edges
Wire	Current wireframe (AIS_WireFrame)
Mesh	Shaded or edge-only triangulation overlay; mesh/triangle edges visible, optional reduced/no fill (TBD — match the accidental wasm look where possible)

• Changing mode should Redisplay the shape immediately (same pattern as material change).
• Default for new shapes: Solid (unchanged).
• Hide all and visibility checkbox behavior unchanged.

Persistence

• Save/load render mode per shape in .ezy JSON (e.g. "render_mode": "solid" | "wire" | "mesh").
• Today only material is persisted; disp_mode is not — add as part of this work.
• Backward compatible: missing key → Solid.

Implementation notes

Existing code:

• Shp::m_disp_mode + set_disp_mode() — src/shp.cpp, src/shp.h
• Shape List UI — src/gui.cpp (~solid/wire checkbox)
• JSON save/load — src/occt_view.cpp (material only today)

Mesh mode (OCCT):

• Likely stays on AIS_Shaded with drawer/aspect tweaks, e.g. Graphic3d_AspectFillArea3d::SetDrawEdges(true) and/or iso-line settings on Prs3d_Drawer
• May require BRepMesh_IncrementalMesh before display so triangulation exists
• Verify identical behavior on desktop and wasm; do not rely on wasm bug side effects

Refactor suggestion:

• Introduce an app-level enum (e.g. Shp_render_mode) mapped to OCCT display + aspect setup, rather than overloading AIS_DisplayMode alone.

Acceptance criteria

• Shape List shows render mode control (dropdown or equivalent) per shape
• Solid, Wire, and Mesh modes work on Windows desktop and wasm
• Mode persists in .ezy and restores on File → Open / undo-redo
• New shapes default to Solid
• No regression to material picker, visibility, or selection

Out of scope (separate issues)

• Fixing OCCT 8 wasm first-display shaded bug (if it remains after Solid mode work)
• Global default render mode in Settings (could follow later)

Related

• Shape List solid/wire checkbox: src/gui.cpp
• Shp::set_disp_mode(): src/shp.cpp