bherbruckandClaude Opus 5.5
c555f6f693
Oracle: 23/29 parts match Fusion. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
76 lines
2.6 KiB
Rust
76 lines
2.6 KiB
Rust
use serde::Serialize;
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use solvecraft_geom::{Aabb3, Mesh, Vec3};
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use crate::Result;
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use crate::body::Body;
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use crate::topo::{TopoCounts, merged_topology};
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/// Measured properties of a body.
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#[derive(Clone, Debug, Serialize)]
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pub struct BodyMeasure {
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pub volume: f64,
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pub area: f64,
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pub centroid: Vec3,
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pub bbox: Aabb3,
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/// Raw kernel topology counts (closed curves and surfaces may be split in pieces).
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pub faces: usize,
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pub edges: usize,
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pub vertices: usize,
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pub shells: usize,
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/// Counts after merging split pieces of the same analytic surface/curve (comparable with
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/// systems that use periodic faces and edges).
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pub merged: TopoCounts,
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}
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/// Per-face sums: area, 6 × signed volume and 24 × first moments (divergence theorem, origin 0).
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fn face_sums(m: &Mesh, nf: usize) -> Vec<(f64, f64, Vec3)> {
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let mut out = vec![(0.0, 0.0, Vec3::ZERO); nf];
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for (t, f) in m.triangles.iter().zip(&m.tri_face) {
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let (Some([a, b, c]), Some(slot)) = (m.tri(t), out.get_mut(*f as usize)) else { continue };
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let d = a.dot(b.cross(c));
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slot.0 += (b - a).cross(c - a).len() * 0.5;
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slot.1 += d;
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slot.2 += (a + b + c) * d;
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}
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out
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}
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/// Measure a body from a fine tessellation (chord tolerance 5e-5 of the body size). Faces whose
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/// fine tessellation disagrees with a coarse one (a meshing failure) use the coarse result.
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pub fn measure(b: &Body) -> Result<BodyMeasure> {
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let size = b.size();
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let fine = b.tessellate((size * 5e-5).max(1e-4))?;
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let medium = b.tessellate((size * 2.5e-4).max(2e-4))?;
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let coarse = b.tessellate((size * 1e-3).max(1e-3))?;
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let nf = b.face_count();
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let (sf, sm, sc) = (face_sums(&fine, nf), face_sums(&medium, nf), face_sums(&coarse, nf));
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let close = |x: f64, y: f64| (x - y).abs() <= 0.01 * x.abs().max(y.abs()) + 1e-9;
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let (mut area, mut v6, mut mom) = (0.0, 0.0, Vec3::ZERO);
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for ((f, m), c) in sf.iter().zip(&sm).zip(&sc) {
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// Trust the finest tessellation that agrees with the next coarser one.
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let pick = if close(f.0, m.0) {
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f
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} else if close(m.0, c.0) {
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m
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} else {
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f
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};
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area += pick.0;
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v6 += pick.1;
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mom += pick.2;
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}
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let volume = v6 / 6.0;
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let centroid = if v6.abs() > 1e-12 { mom / (4.0 * v6) } else { fine.bounds().center() };
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Ok(BodyMeasure {
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volume,
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area,
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centroid,
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bbox: coarse.bounds().union(&fine.bounds()),
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faces: b.face_count(),
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edges: b.edge_count(),
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vertices: b.vertex_count(),
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shells: b.shell_count(),
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merged: merged_topology(b, &coarse)?,
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})
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}
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