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fix(properties): measure bulged polylines exactly

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This commit is contained in:
ramox81 2026-08-18 16:46:16 +03:00
commit c17c25fef1
1 changed files with 16 additions and 6 deletions
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22
src/entities/lwpolyline.rs
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@ -1053,9 +1053,20 @@ impl crate::entities::traits::MassPropsCalc for acadrust::entities::LwPolyline {
cy: 0.0, cy: 0.0,
}; };
} }
// Shoelace area + perimeter // Measure the actual centreline curve. This includes bulge arcs and
// closes open polylines with a straight segment for area, matching the
// same kernel-backed rule used by the AREA command. A chord-only
// calculation reports zero area for DONUT entities because their two
// semicircular vertices lie on one straight line.
let curve = crate::entities::curve::lwpolyline_curve(p)
.expect("an LwPolyline with at least two vertices has a planar curve");
let area = curve.curve.enclosed_area().abs();
let perimeter = curve.length();
// Keep the polygon centroid calculation independent of the exact
// curve measurement above. It is used only by the MASSPROP output;
// Properties consumes the exact area and perimeter.
let mut area_sum = 0.0f64; let mut area_sum = 0.0f64;
let mut perimeter = 0.0f64;
let mut cx_sum = 0.0f64; let mut cx_sum = 0.0f64;
let mut cy_sum = 0.0f64; let mut cy_sum = 0.0f64;
let n_segs = if p.is_closed { n } else { n - 1 }; let n_segs = if p.is_closed { n } else { n - 1 };
@ -1067,13 +1078,12 @@ impl crate::entities::traits::MassPropsCalc for acadrust::entities::LwPolyline {
let x1 = v1.location.x; let x1 = v1.location.x;
let y1 = v1.location.y; let y1 = v1.location.y;
area_sum += x0 * y1 - x1 * y0; area_sum += x0 * y1 - x1 * y0;
perimeter += ((x1 - x0).powi(2) + (y1 - y0).powi(2)).sqrt();
cx_sum += (x0 + x1) * (x0 * y1 - x1 * y0); cx_sum += (x0 + x1) * (x0 * y1 - x1 * y0);
cy_sum += (y0 + y1) * (x0 * y1 - x1 * y0); cy_sum += (y0 + y1) * (x0 * y1 - x1 * y0);
} }
let area = (area_sum / 2.0).abs(); let polygon_area = (area_sum / 2.0).abs();
let (cx, cy) = if area > 1e-12 { let (cx, cy) = if polygon_area > 1e-12 {
(cx_sum / (6.0 * area), cy_sum / (6.0 * area)) (cx_sum / (6.0 * polygon_area), cy_sum / (6.0 * polygon_area))
} else { } else {
let sx: f64 = p.vertices.iter().map(|v| v.location.x).sum::<f64>() / n as f64; let sx: f64 = p.vertices.iter().map(|v| v.location.x).sum::<f64>() / n as f64;
let sy: f64 = p.vertices.iter().map(|v| v.location.y).sum::<f64>() / n as f64; let sy: f64 = p.vertices.iter().map(|v| v.location.y).sum::<f64>() / n as f64;