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Unconstrained triangle sketch failing to converge #238

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b4581e9
Add a unit test for a strange KCL failure
adamchalmers Mar 31, 2026
3cbf5f4
Repro the problem properly
adamchalmers Mar 31, 2026
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120 changes: 116 additions & 4 deletions ezpz/src/tests.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,8 +3,8 @@ use std::{f64::consts::PI, str::FromStr};
use super::*;
use crate::{
datatypes::{
Angle,
inputs::{DatumCircularArc, DatumPoint},
Angle, AngleKind,
inputs::{DatumCircularArc, DatumLineSegment, DatumPoint},
outputs::Point,
},
textual::{OutcomeAnalysis, Problem},
Expand Down Expand Up @@ -334,6 +334,118 @@ fn angle_constraints() {
}
}

#[test]
fn triangle_with_two_angles_accepts_a_side_length_constraint() {
let mut ids = IdGenerator::default();

let line1 = DatumLineSegment::new(DatumPoint::new(&mut ids), DatumPoint::new(&mut ids));
let line2 = DatumLineSegment::new(DatumPoint::new(&mut ids), DatumPoint::new(&mut ids));
let line3 = DatumLineSegment::new(DatumPoint::new(&mut ids), DatumPoint::new(&mut ids));

let initial_guesses = vec![
(0, 5.12),
(1, -3.84),
(2, 30.36),
(3, 13.16),
(4, -11.5),
(5, 10.93),
(6, -68.72),
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@adamchalmers adamchalmers Mar 31, 2026

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Changing the -68 to a -28 makes this test case converge. I think this shows a problem with one of our constraints stability, I think it should be reasonable to find convergence here.

(7, 47.11),
(8, 19.83),
(9, -2.54),
(10, 6.78),
(11, -20.41),
];

let config = Config::default();
let requests_with_size = vec![
// User-defined constraints.
// Make the three lines form a triangle:
ConstraintRequest::new(
Constraint::PointsCoincident(
DatumPoint { x_id: 2, y_id: 3 },
DatumPoint { x_id: 4, y_id: 5 },
),
0,
),
ConstraintRequest::new(
Constraint::PointsCoincident(
DatumPoint { x_id: 6, y_id: 7 },
DatumPoint { x_id: 8, y_id: 9 },
),
0,
),
ConstraintRequest::new(
Constraint::PointsCoincident(
DatumPoint { x_id: 10, y_id: 11 },
DatumPoint { x_id: 0, y_id: 1 },
),
0,
),
// Fix two of the angles:
ConstraintRequest::new(
Constraint::LinesAtAngle(
DatumLineSegment {
p0: DatumPoint { x_id: 8, y_id: 9 },
p1: DatumPoint { x_id: 10, y_id: 11 },
},
DatumLineSegment {
p0: DatumPoint { x_id: 0, y_id: 1 },
p1: DatumPoint { x_id: 2, y_id: 3 },
},
AngleKind::Other(Angle::from_degrees(119.21)),
),
0,
),
ConstraintRequest::new(
Constraint::LinesAtAngle(
DatumLineSegment {
p0: DatumPoint { x_id: 0, y_id: 1 },
p1: DatumPoint { x_id: 2, y_id: 3 },
},
DatumLineSegment {
p0: DatumPoint { x_id: 4, y_id: 5 },
p1: DatumPoint { x_id: 6, y_id: 7 },
},
AngleKind::Perpendicular,
),
0,
),
// Fix the size of one of the triangle's sides..
ConstraintRequest::new(
Constraint::Distance(
DatumPoint { x_id: 4, y_id: 5 },
DatumPoint { x_id: 6, y_id: 7 },
71.24,
),
0,
),
];

let solved_with_size = solve(&requests_with_size, initial_guesses, config)
.expect("triangle with an explicit side length should solve");
assert!(
solved_with_size.is_satisfied(),
"adding the side-length constraint should still produce a satisfied solve"
);

let solved_point = |point: DatumPoint| Point {
x: solved_with_size.final_values[point.id_x() as usize],
y: solved_with_size.final_values[point.id_y() as usize],
};

assert_points_eq(solved_point(line1.p1), solved_point(line2.p0));
assert_points_eq(solved_point(line2.p1), solved_point(line3.p0));
assert_points_eq(solved_point(line3.p1), solved_point(line1.p0));

let solved_line2_start = solved_point(line2.p0);
let solved_line2_end = solved_point(line2.p1);
assert_nearly_eq(
solved_line2_start.euclidean_distance(solved_line2_end),
71.24,
);
}

#[test]
fn perpendicular() {
let solved = run("perpendicular");
Expand Down Expand Up @@ -845,8 +957,8 @@ fn strange_nonconvergence() {
ConstraintRequest::highest_priority(Constraint::PointsCoincident(r, s)),
ConstraintRequest::highest_priority(Constraint::PointsCoincident(q, p)),
ConstraintRequest::highest_priority(Constraint::LinesEqualLength(
datatypes::inputs::DatumLineSegment { p0: q, p1: r },
datatypes::inputs::DatumLineSegment { p0: s, p1: t },
DatumLineSegment { p0: q, p1: r },
DatumLineSegment { p0: s, p1: t },
)),
];
let initial_guesses = vec![
Expand Down
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