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Offering fallible treatment of initial mesh identification (fix for p…
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…anicking convex hull transformation)
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@bellwether-softworks @sebcrozet
bellwether-softworks authored and sebcrozet committed Jan 15, 2023
1 parent 9e7abd6 commit dd114a4
Showing 1 changed file with 107 additions and 50 deletions.
157 changes: 107 additions & 50 deletions src/transformation/convex_hull3/initial_mesh.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,26 @@ use crate::utils;
use na::{Point2, Point3, Vector3};
use std::cmp::Ordering;

#[derive(Debug, PartialEq)]
pub enum InitialMeshError {
AssertionFailed(&'static str),
MissingSupportPoint,
Unreachable,
}

impl std::fmt::Display for InitialMeshError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
InitialMeshError::AssertionFailed(reason) => write!(f, "AssertionFailed({})", reason),
InitialMeshError::MissingSupportPoint => write!(f, "MissingSupportPoint"),
InitialMeshError::Unreachable => write!(f, "Unreachable"),
}
}
}

impl std::error::Error for InitialMeshError {}

#[derive(Debug)]
pub enum InitialMesh {
Facets(Vec<TriangleFacet>),
ResultMesh(Vec<Point3<Real>>, Vec<[u32; 3]>),
Expand Down Expand Up @@ -37,6 +57,14 @@ pub fn get_initial_mesh(
normalized_points: &mut [Point3<Real>],
undecidable: &mut Vec<usize>,
) -> InitialMesh {
try_get_initial_mesh(original_points, normalized_points, undecidable).unwrap()
}

pub fn try_get_initial_mesh(
original_points: &[Point3<Real>],
normalized_points: &mut [Point3<Real>],
undecidable: &mut Vec<usize>,
) -> Result<InitialMesh, InitialMeshError> {
/*
* Compute the eigenvectors to see if the input data live on a subspace.
*/
Expand Down Expand Up @@ -92,12 +120,12 @@ pub fn get_initial_mesh(
0 => {
// The hull is a point.
let (vtx, idx) = build_degenerate_mesh_point(original_points[0].clone());
InitialMesh::ResultMesh(vtx, idx)
Ok(InitialMesh::ResultMesh(vtx, idx))
}
1 => {
// The hull is a segment.
let (vtx, idx) = build_degenerate_mesh_segment(&eigpairs[0].0, original_points);
InitialMesh::ResultMesh(vtx, idx)
Ok(InitialMesh::ResultMesh(vtx, idx))
}
2 => {
// The hull is a triangle.
Expand Down Expand Up @@ -137,7 +165,7 @@ pub fn get_initial_mesh(
triangles.push([a, id + 1, id]);
}

InitialMesh::ResultMesh(coords, triangles)
Ok(InitialMesh::ResultMesh(coords, triangles))
}
3 => {
// The hull is a polyhedron.
Expand All @@ -148,8 +176,10 @@ pub fn get_initial_mesh(
*point = Point3::from((*point - center) / eigval.amax());
}

let p1 = support_point_id(&eigpairs[0].0, normalized_points).unwrap();
let p2 = support_point_id(&-eigpairs[0].0, normalized_points).unwrap();
let p1 = support_point_id(&eigpairs[0].0, normalized_points)
.ok_or(InitialMeshError::MissingSupportPoint)?;
let p2 = support_point_id(&-eigpairs[0].0, normalized_points)
.ok_or(InitialMeshError::MissingSupportPoint)?;

let mut max_area = 0.0;
let mut p3 = usize::max_value();
Expand All @@ -164,61 +194,88 @@ pub fn get_initial_mesh(
}
}

assert!(
p3 != usize::max_value(),
"Internal convex hull error: no triangle found."
);

// Build two facets with opposite normals
let mut f1 = TriangleFacet::new(p1, p2, p3, normalized_points);
let mut f2 = TriangleFacet::new(p2, p1, p3, normalized_points);

// Link the facets together
f1.set_facets_adjascency(1, 1, 1, 0, 2, 1);
f2.set_facets_adjascency(0, 0, 0, 0, 2, 1);

let mut facets = vec![f1, f2];

// … and attribute visible points to each one of them.
// FIXME: refactor this with the two others.
let mut ignored = 0usize;
for point in 0..normalized_points.len() {
if normalized_points[point] == normalized_points[p1]
|| normalized_points[point] == normalized_points[p2]
|| normalized_points[point] == normalized_points[p3]
{
continue;
}
if p3 == usize::max_value() {
Err(InitialMeshError::AssertionFailed("Internal convex hull error: no triangle found."))
} else {
// Build two facets with opposite normals
let mut f1 = TriangleFacet::new(p1, p2, p3, normalized_points);
let mut f2 = TriangleFacet::new(p2, p1, p3, normalized_points);

// Link the facets together
f1.set_facets_adjascency(1, 1, 1, 0, 2, 1);
f2.set_facets_adjascency(0, 0, 0, 0, 2, 1);

let mut facets = vec![f1, f2];

// … and attribute visible points to each one of them.
// FIXME: refactor this with the two others.
let mut ignored = 0usize;
for point in 0..normalized_points.len() {
if normalized_points[point] == normalized_points[p1]
|| normalized_points[point] == normalized_points[p2]
|| normalized_points[point] == normalized_points[p3]
{
continue;
}

let mut furthest = usize::max_value();
let mut furthest_dist = 0.0;
let mut furthest = usize::max_value();
let mut furthest_dist = 0.0;

for (i, curr_facet) in facets.iter().enumerate() {
if curr_facet.can_see_point(point, normalized_points) {
let distance = curr_facet.distance_to_point(point, normalized_points);
for (i, curr_facet) in facets.iter().enumerate() {
if curr_facet.can_see_point(point, normalized_points) {
let distance = curr_facet.distance_to_point(point, normalized_points);

if distance > furthest_dist {
furthest = i;
furthest_dist = distance;
if distance > furthest_dist {
furthest = i;
furthest_dist = distance;
}
}
}
}

if furthest != usize::max_value() {
facets[furthest].add_visible_point(point, normalized_points);
} else {
undecidable.push(point);
ignored = ignored + 1;
if furthest != usize::max_value() {
facets[furthest].add_visible_point(point, normalized_points);
} else {
undecidable.push(point);
ignored = ignored + 1;
}

// If none of the facet can be seen from the point, it is naturally deleted.
}

// If none of the facet can be seen from the point, it is naturally deleted.
super::check_facet_links(0, &facets[..]);
super::check_facet_links(1, &facets[..]);

Ok(InitialMesh::Facets(facets))
}
}
_ => Err(InitialMeshError::Unreachable),
}
}

super::check_facet_links(0, &facets[..]);
super::check_facet_links(1, &facets[..]);
#[cfg(test)]
mod tests {
#[test]
#[cfg(feature = "f32")]
fn try_get_initial_mesh_should_fail_for_missing_support_points() {
use na::Point3;
use super::*;
use crate::transformation::convex_hull_utils::normalize;

InitialMesh::Facets(facets)
}
_ => unreachable!(),
let point_cloud = vec![
Point3::new(103.05024, 303.44974, 106.125),
Point3::new(103.21692, 303.44974, 106.125015),
Point3::new(104.16538, 303.44974, 106.125),
Point3::new(106.55025, 303.44974, 106.125),
Point3::new(106.55043, 303.44974, 106.125),
];

let mut normalized_points = point_cloud.to_vec();
let _ = normalize(&mut normalized_points[..]);

let mut undecidable_points = vec![];

let result = try_get_initial_mesh(&point_cloud, &mut normalized_points, &mut undecidable_points);

assert_eq!(InitialMeshError::MissingSupportPoint, result.unwrap_err());
}
}

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