Giovanni
e489e56f3d
Loft faces between sections are spaced by chord length instead of by parameter, so uneven sections no longer twist the surface. Fixes #968.
78 lines
3.8 KiB
Rust
78 lines
3.8 KiB
Rust
//! Lofted round tubes through sections that are not evenly spaced.
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//!
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//! A loft's surface used to pass through its sections at uniform parameters, so a section close to
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//! its neighbour (a bore that runs 5 mm past the end of a tube whose other sections are 12 mm
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//! apart, or 60 mm in a snail) made the surface overshoot between the others, by several times the
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//! tube's radius. The overshoot also made booleans with the tube fail for some section counts and
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//! not for their neighbours.
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use std::f64::consts::PI;
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use super::*;
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/// `sections` circles of radius `radius` centred on an arc of radius `path` turning `angle`
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/// (radians), in planes normal to the arc, lofted into the body `body`; `over` extends the
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/// sections past both ends along the tangent.
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fn tube(s: &mut Session, body: &str, radius: f64, path: f64, angle: f64, sections: usize, over: f64) {
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let mut stations: Vec<[f64; 4]> = (0..sections)
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.map(|i| {
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let t = angle * i as f64 / (sections - 1) as f64;
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[path * t.cos(), path * t.sin(), -t.sin(), t.cos()]
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})
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.collect();
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if over > 0.0 {
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let (a, b) = (stations[0], stations[sections - 1]);
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stations.insert(0, [a[0] - over * a[2], a[1] - over * a[3], a[2], a[3]]);
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stations.push([b[0] + over * b[2], b[1] + over * b[3], b[2], b[3]]);
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}
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let mut list = Vec::new();
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for (i, [x, y, tx, ty]) in stations.iter().enumerate() {
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let name = format!("{body}{i}");
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run(s, "sketch.create", json!({"plane": {"origin": [x, y, 0], "x_dir": [0, 0, 1], "y_dir": [ty, -tx, 0]}, "name": name}));
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run(s, "sketch.circle.center", json!({"center": [0, 0], "radius": radius}));
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run(s, "sketch.finish", json!({}));
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list.push(json!({"sketch": name}));
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}
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run(s, "solid.loft", json!({"sections": list, "operation": "new", "name": format!("Loft{body}"), "body_name": body}));
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}
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fn bounds(s: &mut Session, body: &str) -> ([f64; 3], [f64; 3]) {
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let m = run(s, "inspect.measure", json!({}));
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let b = m["bodies"].as_array().unwrap().iter().find(|b| b["name"] == body).unwrap();
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let get = |k: &str| -> [f64; 3] {
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let v = b["bbox"][k].as_array().unwrap();
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[v[0].as_f64().unwrap(), v[1].as_f64().unwrap(), v[2].as_f64().unwrap()]
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};
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(get("min"), get("max"))
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}
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#[test]
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fn a_bore_with_a_short_overrun_stays_inside_its_tube() {
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// 14 sections 12 mm apart, and one more 5 mm beyond each end: the bore is a tube of radius 18
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// around the arc (z within 18 of the arc's plane), and used to reach z = 88.
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let mut s = Session::default();
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tube(&mut s, "Bore", 18.0, 100.0, PI / 2.0, 14, 5.0);
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let (lo, hi) = bounds(&mut s, "Bore");
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assert!(hi[2] < 18.0 + 0.1 && lo[2] > -18.0 - 0.1, "z from {} to {}", lo[2], hi[2]);
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let want = PI * 18.0 * 18.0 * (100.0 * PI / 2.0 + 10.0);
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let got = volume(&mut s);
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assert!(rel(got, want) < 2e-3, "{got} vs {want}");
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}
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#[test]
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fn a_hollow_elbow_is_cut_for_any_number_of_sections() {
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let (path, outer, inner) = (100.0, 30.0, 18.0);
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// Each of these gave "no result" (the first six) or failed in another way.
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for (degrees, sections) in [(60.0, 5), (60.0, 7), (90.0, 10), (90.0, 14), (120.0, 7), (120.0, 13)] {
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let angle = degrees * PI / 180.0;
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let mut s = Session::default();
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tube(&mut s, "Outer", outer, path, angle, sections, 0.0);
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tube(&mut s, "Inner", inner, path, angle, sections, 5.0);
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run(&mut s, "solid.combine", json!({"target": "Outer", "tools": ["Inner"], "operation": "cut", "name": "Hollow"}));
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assert_eq!(s.model.state().bodies.len(), 1, "{degrees} degrees, {sections} sections");
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let want = PI * (outer * outer - inner * inner) * path * angle;
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let got = volume(&mut s);
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assert!(rel(got, want) < 3e-3, "{degrees} degrees, {sections} sections: {got} vs {want}");
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}
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}
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