Files
OneCAD-Draft/src/entities/lwpolyline.rs
T
Hakan SevenandClaude Opus 4.8 4d2471cafd feat(properties): audit editable vs read-only across all entities
Reclassify every property row to match standard palette behaviour: a row
is editable only when its value maps directly to a stored field AND its
apply_geom_prop handler is wired; computed/derived/count/handle/
cross-object values stay read-only.

Newly editable (all apply-wired): attribute tag/prompt; ellipse major
radius; hatch Double; lwpolyline closed/linetype-gen; mline style;
multileader annotative/landing/background-fill; polyline 2D+3D vertex
coords/segment widths/linetype-gen; shape style; spline control/fit
point coords, weight, fit tolerance, tangents; table break-option flags;
text alignment point, upside-down, backward; underlay display flags.

Corrections: spline Degree -> read-only (editing desynced the knot
vector); removed a duplicate leader "Arrowhead" row.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-07-03 08:06:00 +03:00

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use acadrust::entities::{LwPolyline, LwVertex};
use truck_modeling::{builder, Edge, Point3, Wire};
use crate::command::EntityTransform;
use crate::entities::common::{
edit_prop as edit, parse_f64, rectangle_grip, ro_prop as ro, square_grip,
};
use crate::entities::traits::TruckConvertible;
use crate::scene::convert::acad_to_truck::{TruckEntity, TruckObject};
use crate::scene::model::object::{GripApply, GripDef, PropSection, PropValue, Property};
use crate::scene::model::wire_model::TangentGeom;
const TAU: f64 = std::f64::consts::TAU;
/// Midpoint position on an arc segment defined by its bulge.
fn arc_midpoint(p0: [f64; 2], p1: [f64; 2], bulge: f64) -> [f64; 2] {
match crate::entities::common::BulgeArc::from_bulge(p0, p1, bulge) {
Some(arc) => arc.sample(0.5),
None => [(p0[0] + p1[0]) * 0.5, (p0[1] + p1[1]) * 0.5],
}
}
/// Compute the DXF bulge for an arc that passes through p0, mid_pt, and p1.
/// Returns None when the three points are collinear (straight segment).
fn bulge_from_midpoint(p0: [f64; 2], p1: [f64; 2], mid: [f64; 2]) -> Option<f64> {
// Circumcircle of (p0, mid, p1)
let ax = 2.0 * (mid[0] - p0[0]);
let ay = 2.0 * (mid[1] - p0[1]);
let bx = 2.0 * (p1[0] - p0[0]);
let by = 2.0 * (p1[1] - p0[1]);
let ca = mid[0] * mid[0] + mid[1] * mid[1] - p0[0] * p0[0] - p0[1] * p0[1];
let cb = p1[0] * p1[0] + p1[1] * p1[1] - p0[0] * p0[0] - p0[1] * p0[1];
let det = ax * by - ay * bx;
if det.abs() < 1e-12 {
return None; // collinear
}
let cx = (ca * by - cb * ay) / det;
let cy = (ax * cb - bx * ca) / det;
let a0 = (p0[1] - cy).atan2(p0[0] - cx);
let a1 = (p1[1] - cy).atan2(p1[0] - cx);
// Determine arc direction: cross product (p1-p0) × (mid-p0)
let cross = (p1[0] - p0[0]) * (mid[1] - p0[1]) - (p1[1] - p0[1]) * (mid[0] - p0[0]);
let (sa, mut ea) = if cross > 0.0 { (a0, a1) } else { (a1, a0) };
if ea < sa {
ea += TAU;
}
let span = ea - sa; // central angle in (0, TAU]
let bulge = (span / 4.0).tan();
Some(if cross >= 0.0 { bulge } else { -bulge })
}
/// Tessellate a thick polyline segment list into NaN-separated Lines geometry.
/// Shared by LwPolyline and Polyline2D thickness paths.
fn thick_segments(
seg_data: &[(f64, f64, f64, f64)], // (x0, y0, x1, y1) per seg — or use run of (x,y,bulge)
path_pts: &[[f64; 3]],
thickness: f64,
normal: (f64, f64, f64),
key_verts: Vec<[f64; 3]>,
tangents: Vec<TangentGeom>,
) -> TruckEntity {
let (nx, ny, nz) = normal;
let t = thickness;
let off = |p: [f64; 3]| -> [f64; 3] { [p[0] + t * nx, p[1] + t * ny, p[2] + t * nz] };
let mut pts: Vec<[f64; 3]> = Vec::with_capacity(path_pts.len() * 2 + seg_data.len() * 3 + 4);
// Bottom path
pts.extend_from_slice(path_pts);
pts.push([f64::NAN; 3]);
// Top path
for &p in path_pts {
pts.push(off(p));
}
// Walls at each vertex (seg_data.0/.1 = start x/y of each seg, last seg appends its end too)
if !seg_data.is_empty() {
pts.push([f64::NAN; 3]);
for (k, &(x0, y0, _x1, _y1)) in seg_data.iter().enumerate() {
let pb = key_verts[k];
let _ = (x0, y0); // key_verts already has correct WCS
pts.push(pb);
pts.push(off(pb));
if k + 1 < seg_data.len() {
pts.push([f64::NAN; 3]);
}
}
// Last wall at the final vertex
if let Some(&last) = key_verts.last() {
pts.push([f64::NAN; 3]);
pts.push(last);
pts.push(off(last));
}
}
TruckEntity {
object: TruckObject::Lines(pts),
snap_pts: vec![],
tangent_geoms: tangents,
key_vertices: key_verts,
fill_tris: vec![],
}
}
fn to_truck(pline: &LwPolyline) -> TruckEntity {
let verts = &pline.vertices;
if verts.is_empty() {
return TruckEntity {
object: TruckObject::Point(builder::vertex(Point3::new(0.0, 0.0, 0.0))),
snap_pts: vec![],
tangent_geoms: vec![],
key_vertices: vec![],
fill_tris: vec![],
};
}
let elev = pline.elevation;
let normal = (pline.normal.x, pline.normal.y, pline.normal.z);
let count = verts.len();
let seg_count = if pline.is_closed { count } else { count - 1 };
let mut edges: Vec<Edge> = Vec::new();
let mut tangents: Vec<TangentGeom> = Vec::new();
let mut key_verts: Vec<[f64; 3]> = Vec::new();
// Convert OCS (x, y, elevation) to WCS Point3.
let to_wcs = |x: f64, y: f64| -> (f64, f64, f64) {
crate::scene::view::transform::ocs_point_to_wcs((x, y, elev), normal)
};
let to_pt = |v: &LwVertex| -> Point3 {
let (wx, wy, wz) = to_wcs(v.location.x, v.location.y);
Point3::new(wx, wy, wz)
};
if pline.thickness.abs() > 1e-10 {
let mut path: Vec<[f64; 3]> = Vec::new();
let mut kv: Vec<[f64; 3]> = Vec::new();
let mut tgs: Vec<TangentGeom> = Vec::new();
let mut seg_data: Vec<(f64, f64, f64, f64)> = Vec::new();
// First vertex
let (w0x, w0y, w0z) = to_wcs(verts[0].location.x, verts[0].location.y);
path.push([w0x, w0y, w0z]);
kv.push([w0x, w0y, w0z]);
for i in 0..seg_count {
let va = &verts[i];
let vb = &verts[(i + 1) % count];
let (ox0, oy0) = (va.location.x, va.location.y);
let (ox1, oy1) = (vb.location.x, vb.location.y);
let bulge = va.bulge;
if bulge.abs() < 1e-9 {
let (wx, wy, wz) = to_wcs(ox1, oy1);
path.push([wx, wy, wz]);
let p1_pt = path[path.len() - 2];
let p2_pt = *path.last().unwrap();
tgs.push(TangentGeom::Line {
p1: [p1_pt[0] as f32, p1_pt[1] as f32, p1_pt[2] as f32],
p2: [p2_pt[0] as f32, p2_pt[1] as f32, p2_pt[2] as f32],
});
} else if let Some(arc) =
crate::entities::common::BulgeArc::from_bulge([ox0, oy0], [ox1, oy1], bulge)
{
let (wcx, wcy, wcz) = to_wcs(arc.center[0], arc.center[1]);
tgs.push(TangentGeom::Circle {
center: [wcx as f32, wcy as f32, wcz as f32],
radius: arc.radius as f32,
});
for j in 1..=16usize {
let s = arc.sample(j as f64 / 16.0);
let (wx, wy, wz) = to_wcs(s[0], s[1]);
path.push([wx, wy, wz]);
}
}
let (wbx, wby, wbz) = to_wcs(ox1, oy1);
kv.push([wbx, wby, wbz]);
seg_data.push((ox0, oy0, ox1, oy1));
}
return thick_segments(&seg_data, &path, pline.thickness, normal, kv, tgs);
}
// plinegen=false: NaN-separated segments so the linetype pattern restarts per vertex.
if !pline.plinegen {
let mut pts: Vec<[f64; 3]> = Vec::new();
let mut tgs: Vec<TangentGeom> = Vec::new();
let mut kv: Vec<[f64; 3]> = Vec::new();
let to_f32 = |p: [f64; 3]| -> [f32; 3] { [p[0] as f32, p[1] as f32, p[2] as f32] };
for i in 0..seg_count {
let va = &verts[i];
let vb = &verts[(i + 1) % count];
let (ox0, oy0) = (va.location.x, va.location.y);
let (ox1, oy1) = (vb.location.x, vb.location.y);
let bulge = va.bulge;
let (wx0, wy0, wz0) = to_wcs(ox0, oy0);
let p_start = [wx0, wy0, wz0];
pts.push(p_start);
if i == 0 {
kv.push(p_start);
}
if bulge.abs() < 1e-9 {
let (wx1, wy1, wz1) = to_wcs(ox1, oy1);
let p_end = [wx1, wy1, wz1];
pts.push(p_end);
kv.push(p_end);
tgs.push(TangentGeom::Line {
p1: to_f32(p_start),
p2: to_f32(p_end),
});
} else if let Some(arc) =
crate::entities::common::BulgeArc::from_bulge([ox0, oy0], [ox1, oy1], bulge)
{
for j in 1..=16usize {
let s = arc.sample(j as f64 / 16.0);
let (wx, wy, wz) = to_wcs(s[0], s[1]);
pts.push([wx, wy, wz]);
}
let (wx1, wy1, wz1) = to_wcs(ox1, oy1);
kv.push([wx1, wy1, wz1]);
let (wcx, wcy, wcz) = to_wcs(arc.center[0], arc.center[1]);
tgs.push(TangentGeom::Circle {
center: [wcx as f32, wcy as f32, wcz as f32],
radius: arc.radius as f32,
});
}
if i + 1 < seg_count {
pts.push([f64::NAN; 3]);
}
}
return TruckEntity {
object: TruckObject::SegmentedLines(pts),
snap_pts: vec![],
tangent_geoms: tgs,
key_vertices: kv,
fill_tris: vec![],
};
}
for i in 0..seg_count {
let v0 = &verts[i];
let v1 = &verts[(i + 1) % count];
let p0 = to_pt(v0);
let p1 = to_pt(v1);
let bulge = v0.bulge;
if bulge.abs() < 1e-9 {
let tv0 = builder::vertex(p0);
let tv1 = builder::vertex(p1);
edges.push(builder::line(&tv0, &tv1));
tangents.push(TangentGeom::Line {
p1: [p0.x as f32, p0.y as f32, p0.z as f32],
p2: [p1.x as f32, p1.y as f32, p1.z as f32],
});
} else if let Some(arc) = crate::entities::common::BulgeArc::from_bulge(
[v0.location.x, v0.location.y],
[v1.location.x, v1.location.y],
bulge as f64,
) {
let mid_s = arc.sample(0.5);
let (mid_wx, mid_wy, mid_wz) = to_wcs(mid_s[0], mid_s[1]);
let p_mid = Point3::new(mid_wx, mid_wy, mid_wz);
let tv0 = builder::vertex(p0);
let tv1 = builder::vertex(p1);
edges.push(builder::circle_arc(&tv0, &tv1, p_mid));
let (wcx, wcy, wcz) = to_wcs(arc.center[0], arc.center[1]);
tangents.push(TangentGeom::Circle {
center: [wcx as f32, wcy as f32, wcz as f32],
radius: arc.radius as f32,
});
}
if i == 0 {
key_verts.push([p0.x, p0.y, p0.z]);
}
key_verts.push([p1.x, p1.y, p1.z]);
}
TruckEntity {
object: TruckObject::Contour(edges.into_iter().collect::<Wire>()),
snap_pts: vec![],
tangent_geoms: tangents,
key_vertices: key_verts,
fill_tris: vec![],
}
}
fn grips(pline: &LwPolyline) -> Vec<GripDef> {
let elev = pline.elevation;
let n = pline.vertices.len();
let seg_count = if pline.is_closed {
n
} else {
n.saturating_sub(1)
};
let mut out: Vec<GripDef> = pline
.vertices
.iter()
.enumerate()
.map(|(i, v)| square_grip(i, glam::DVec3::new(v.location.x, v.location.y, elev)))
.collect();
// One mid-segment stretch grip per segment (straight or arc). The
// marker is a small box rotated along the chord direction so the
// shape itself signals which way the segment runs.
for i in 0..seg_count {
let v0 = &pline.vertices[i];
let v1 = &pline.vertices[(i + 1) % n];
let (mx, my) = if v0.bulge.abs() < 1e-9 {
(
(v0.location.x + v1.location.x) * 0.5,
(v0.location.y + v1.location.y) * 0.5,
)
} else {
let m = arc_midpoint(
[v0.location.x, v0.location.y],
[v1.location.x, v1.location.y],
v0.bulge,
);
(m[0], m[1])
};
let dx = (v1.location.x - v0.location.x) as f32;
let dy = (v1.location.y - v0.location.y) as f32;
out.push(rectangle_grip(
n + i,
glam::DVec3::new(mx, my, elev),
[dx, dy],
));
}
out
}
fn properties(pline: &LwPolyline) -> Vec<PropSection> {
let v0 = pline.vertices.first();
let vx = v0.map_or(0.0, |v| v.location.x);
let vy = v0.map_or(0.0, |v| v.location.y);
let start_w = v0.map_or(0.0, |v| v.start_width);
let end_w = v0.map_or(0.0, |v| v.end_width);
vec![
PropSection {
title: "Geometry".into(),
props: vec![
ro("Current Vertex", "current_vertex", String::new()),
edit("Vertex X", "vertex_x", vx),
edit("Vertex Y", "vertex_y", vy),
edit("Start segment width", "start_width", start_w),
edit("End segment width", "end_width", end_w),
edit("Global width", "global_width", pline.constant_width),
edit("Elevation", "elevation", pline.elevation),
],
},
PropSection {
title: "Misc".into(),
props: vec![
Property {
label: "Closed".into(),
field: "closed",
value: PropValue::BoolToggle {
field: "closed",
value: pline.is_closed,
},
},
Property {
label: "Linetype generation".into(),
field: "plinegen",
value: PropValue::BoolToggle {
field: "plinegen",
value: pline.plinegen,
},
},
],
},
]
}
fn apply_geom_prop(pline: &mut LwPolyline, field: &str, value: &str) {
match field {
"closed" => {
pline.is_closed = if value == "toggle" {
!pline.is_closed
} else {
value == "true"
};
return;
}
"plinegen" => {
pline.plinegen = if value == "toggle" {
!pline.plinegen
} else {
value == "true"
};
return;
}
_ => {}
}
let Some(v) = parse_f64(value) else {
return;
};
match field {
"elevation" => pline.elevation = v,
"global_width" => pline.constant_width = v,
"vertex_x" => {
if let Some(vtx) = pline.vertices.first_mut() {
vtx.location.x = v;
}
}
"vertex_y" => {
if let Some(vtx) = pline.vertices.first_mut() {
vtx.location.y = v;
}
}
"start_width" => {
if let Some(vtx) = pline.vertices.first_mut() {
vtx.start_width = v;
}
}
"end_width" => {
if let Some(vtx) = pline.vertices.first_mut() {
vtx.end_width = v;
}
}
_ => {}
}
}
fn apply_grip(pline: &mut LwPolyline, grip_id: usize, apply: GripApply) {
let n = pline.vertices.len();
if grip_id < n {
// Vertex position grip
let v = &mut pline.vertices[grip_id];
match apply {
GripApply::Absolute(p) => {
v.location.x = p.x as f64;
v.location.y = p.y as f64;
}
GripApply::Translate(d) => {
v.location.x += d.x as f64;
v.location.y += d.y as f64;
}
}
} else {
// Mid-segment stretch grip for segment (grip_id - n).
// Straight segments translate both endpoints by the drag delta
// (the shared vertices then carry along whichever adjacent
// segments share them). Arc segments adjust their bulge from
// the new midpoint position.
let seg = grip_id - n;
let count = if pline.is_closed {
n
} else {
n.saturating_sub(1)
};
if seg >= count {
return;
}
let i0 = seg;
let i1 = (seg + 1) % n;
let is_arc = pline.vertices[i0].bulge.abs() >= 1e-9;
if !is_arc {
let d = match apply {
GripApply::Translate(d) => [d.x as f64, d.y as f64],
GripApply::Absolute(p) => {
let old_mid = (
(pline.vertices[i0].location.x + pline.vertices[i1].location.x) * 0.5,
(pline.vertices[i0].location.y + pline.vertices[i1].location.y) * 0.5,
);
[p.x as f64 - old_mid.0, p.y as f64 - old_mid.1]
}
};
pline.vertices[i0].location.x += d[0];
pline.vertices[i0].location.y += d[1];
pline.vertices[i1].location.x += d[0];
pline.vertices[i1].location.y += d[1];
return;
}
let new_mid: [f64; 2] = match apply {
GripApply::Absolute(p) => [p.x as f64, p.y as f64],
GripApply::Translate(d) => {
let v0 = &pline.vertices[i0];
let v1 = &pline.vertices[i1];
let old = arc_midpoint(
[v0.location.x, v0.location.y],
[v1.location.x, v1.location.y],
v0.bulge,
);
[old[0] + d.x as f64, old[1] + d.y as f64]
}
};
let p0 = [pline.vertices[i0].location.x, pline.vertices[i0].location.y];
let p1 = [pline.vertices[i1].location.x, pline.vertices[i1].location.y];
if let Some(new_bulge) = bulge_from_midpoint(p0, p1, new_mid) {
pline.vertices[i0].bulge = new_bulge.clamp(-1e6, 1e6);
}
}
}
fn apply_transform(pline: &mut LwPolyline, t: &EntityTransform) {
crate::scene::view::transform::apply_standard_entity_transform(pline, t, |entity, p1, p2| {
for v in &mut entity.vertices {
crate::scene::view::transform::reflect_xy_point(&mut v.location.x, &mut v.location.y, p1, p2);
// Bulge encodes which side the arc bows to; a reflection
// reverses it or every curved segment flips to the wrong side.
v.bulge = -v.bulge;
}
});
}
impl TruckConvertible for LwPolyline {
fn to_truck(&self, _document: &acadrust::CadDocument) -> Option<TruckEntity> {
Some(to_truck(self))
}
}
impl crate::entities::traits::Grippable for LwPolyline {
fn grips(&self) -> Vec<crate::scene::model::object::GripDef> {
grips(self)
}
fn apply_grip(&mut self, grip_id: usize, apply: crate::scene::model::object::GripApply) {
apply_grip(self, grip_id, apply);
}
fn grip_menu(&self, grip_id: usize) -> Vec<crate::scene::model::object::GripMenuItem> {
use crate::scene::model::object::{GripMenuAction, GripMenuItem};
let n = self.vertices.len();
if grip_id < n {
// Vertex grip.
return vec![
GripMenuItem {
label: "Stretch",
action: GripMenuAction::Stretch,
},
GripMenuItem {
label: "Add Vertex",
action: GripMenuAction::AddVertex,
},
GripMenuItem {
label: "Remove Vertex",
action: GripMenuAction::RemoveVertex,
},
];
}
// Segment midpoint grip.
let seg = grip_id - n;
let is_arc = self
.vertices
.get(seg)
.map_or(false, |v| v.bulge.abs() >= 1e-9);
let convert = if is_arc {
GripMenuItem {
label: "Convert to Line",
action: GripMenuAction::ConvertToLine,
}
} else {
GripMenuItem {
label: "Convert to Arc",
action: GripMenuAction::ConvertToArc,
}
};
vec![
GripMenuItem {
label: "Stretch",
action: GripMenuAction::Stretch,
},
GripMenuItem {
label: "Add Vertex",
action: GripMenuAction::AddVertex,
},
convert,
]
}
fn apply_grip_menu(&mut self, grip_id: usize, action: crate::scene::model::object::GripMenuAction) {
use crate::scene::model::object::GripMenuAction as A;
let n = self.vertices.len();
match action {
A::Stretch => {}
A::AddVertex => {
// Insert a new vertex at the chord midpoint between the
// hovered vertex (or segment) and its neighbour. The new
// vertex inherits the previous vertex's bulge so an
// existing arc is split into two arcs of the same chord.
let (i0, i1) = if grip_id < n {
let i0 = grip_id;
let i1 = (grip_id + 1) % n;
(i0, i1)
} else {
let seg = grip_id - n;
(seg, (seg + 1) % n)
};
if i1 == 0 && !self.is_closed {
return;
}
let v0 = &self.vertices[i0];
let v1 = &self.vertices[i1];
let mx = (v0.location.x + v1.location.x) * 0.5;
let my = (v0.location.y + v1.location.y) * 0.5;
let inherited = v0.clone();
let mut new_v = inherited.clone();
new_v.location.x = mx;
new_v.location.y = my;
let insert_at = (i0 + 1).min(self.vertices.len());
self.vertices.insert(insert_at, new_v);
}
A::RemoveVertex if grip_id < n && self.vertices.len() > 2 => {
self.vertices.remove(grip_id);
}
A::ConvertToArc if grip_id >= n => {
if let Some(v) = self.vertices.get_mut(grip_id - n) {
if v.bulge.abs() < 1e-9 {
v.bulge = 0.5;
}
}
}
A::ConvertToLine if grip_id >= n => {
if let Some(v) = self.vertices.get_mut(grip_id - n) {
v.bulge = 0.0;
}
}
_ => {}
}
}
}
impl crate::entities::traits::PropertyEditable for LwPolyline {
fn geometry_properties(
&self,
_text_style_names: &[String],
) -> Vec<crate::scene::model::object::PropSection> {
properties(self)
}
fn apply_geom_prop(&mut self, field: &str, value: &str) {
apply_geom_prop(self, field, value);
}
}
impl crate::entities::traits::Transformable for LwPolyline {
fn apply_transform(&mut self, t: &crate::command::EntityTransform) {
apply_transform(self, t);
}
}
/// Solid-fill bands for a wide LwPolyline, plus the `world_origin` they are
/// relative to. The band vertices are small f32 offsets from `origin` (the
/// first vertex), so the relative-to-eye hatch fill keeps sub-unit precision at
/// UTM-scale coordinates — building them in absolute f32 collapsed the band into
/// a string of squares far from the origin.
pub(crate) fn wide_fills(pl: &acadrust::entities::LwPolyline) -> ([f64; 2], Vec<Vec<[f32; 2]>>) {
let hw_const = (pl.constant_width / 2.0) as f32;
let verts = &pl.vertices;
let n = verts.len();
if n < 2 {
return ([0.0; 2], vec![]);
}
let origin = [verts[0].location.x, verts[0].location.y];
let seg_count = if pl.is_closed { n } else { n - 1 };
let mut out = Vec::new();
for i in 0..seg_count {
let v0 = &verts[i];
let v1 = &verts[(i + 1) % n];
let hw0 = if v0.start_width > 1e-9 {
v0.start_width as f32 / 2.0
} else {
hw_const
};
let hw1 = if v0.end_width > 1e-9 {
v0.end_width as f32 / 2.0
} else {
hw_const
};
if hw0 < 1e-6 && hw1 < 1e-6 {
continue;
}
let p0 = [
(v0.location.x - origin[0]) as f32,
(v0.location.y - origin[1]) as f32,
];
let p1 = [
(v1.location.x - origin[0]) as f32,
(v1.location.y - origin[1]) as f32,
];
if let Some(poly) =
crate::entities::common::polyline_segment_fill(p0, p1, hw0, hw1, v0.bulge as f32)
{
out.push(poly);
}
}
(origin, out)
}
impl crate::entities::traits::MassPropsCalc for acadrust::entities::LwPolyline {
fn mass_props(&self) -> crate::entities::traits::MassProps {
let p = self;
let n = p.vertices.len();
if n < 2 {
return crate::entities::traits::MassProps {
area: 0.0,
perimeter: 0.0,
cx: 0.0,
cy: 0.0,
};
}
// Shoelace area + perimeter
let mut area_sum = 0.0f64;
let mut perimeter = 0.0f64;
let mut cx_sum = 0.0f64;
let mut cy_sum = 0.0f64;
let n_segs = if p.is_closed { n } else { n - 1 };
for idx in 0..n_segs {
let v0 = &p.vertices[idx];
let v1 = &p.vertices[(idx + 1) % n];
let x0 = v0.location.x;
let y0 = v0.location.y;
let x1 = v1.location.x;
let y1 = v1.location.y;
area_sum += x0 * y1 - x1 * y0;
perimeter += ((x1 - x0).powi(2) + (y1 - y0).powi(2)).sqrt();
cx_sum += (x0 + x1) * (x0 * y1 - x1 * y0);
cy_sum += (y0 + y1) * (x0 * y1 - x1 * y0);
}
let area = (area_sum / 2.0).abs();
let (cx, cy) = if area > 1e-12 {
(cx_sum / (6.0 * area), cy_sum / (6.0 * area))
} else {
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;
(sx, sy)
};
crate::entities::traits::MassProps {
area,
perimeter,
cx,
cy,
}
}
}