geop-cad-base
Brief overview only — full documentation is coming later.
Ray-based picking against kernel geometry: what an interactive CAD editor needs from the kernel beyond building parts.
Picking
let hit: Option<PickHit<S>> = pick(&model, &rasterized, ray, PickFilter::Any, tolerance)?;pick casts a Ray (from the camera through the cursor) and returns the
nearest entity matching the PickFilter as a PickHit: its kind, its id,
the hit point and the ray parameter t. The caller turns the id into the
entity’s stable name, which is what a program step refers to it by.
| Filter | Hits |
|---|---|
Vertex | the nearest vertex within tolerance of the ray |
Edge | the nearest edge within tolerance |
Face | the first face the ray enters |
Solid | the solid owning the first face hit |
Any | a vertex, else an edge, else a face: the smallest entity under the cursor that is not hidden behind a face |
Face hits are exact ray/triangle intersections (Möller–Trumbore). When a division cannot be resolved because its divisor could be zero, the hit is reported as a miss, which is the honest answer when the enclosure cannot rule zero out.
Picking works on the RasterizedModel the viewer drew (see
geop-ops-rasterize) rather than
re-triangulating, so a pick can never disagree with what is on screen.
Rasterizing once per build also makes picking cheap enough to run on every
pointer move, to highlight what a click would pick.
pick_sketch does the same for sketches, against SketchTargets::of(part).
A sketch is hit near one of its curves, or anywhere inside one of its closed
regions.
tolerance is the one plain f64 here. It is a UI fuzziness derived from
screen pixels, not a geometric quantity the kernel reasons about, so it is
compared against to_f64 rather than folded into interval arithmetic.