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Improve preprocessing of snapping (don't move fixed vertices during collapsing)

This commit is contained in:
Mael Rouxel-Labbé 2021-09-28 16:49:19 +02:00
parent 60567eccbb
commit b92c22d0a9
1 changed files with 20 additions and 7 deletions
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27
Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Snapping/snap.h
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@ -92,6 +92,7 @@ void simplify_range(HalfedgeRange& halfedge_range,
typedef typename GT::FT FT; typedef typename GT::FT FT;
typedef typename GetVertexPointMap<TriangleMesh, NamedParameters>::type VPM; typedef typename GetVertexPointMap<TriangleMesh, NamedParameters>::type VPM;
typedef typename boost::property_traits<VPM>::value_type Point;
typedef typename boost::property_traits<VPM>::reference Point_ref; typedef typename boost::property_traits<VPM>::reference Point_ref;
using parameters::get_parameter; using parameters::get_parameter;
@ -125,10 +126,10 @@ void simplify_range(HalfedgeRange& halfedge_range,
// @fixme what if the source vertex is not to be snapped? Tolerance cannot be obtained... // @fixme what if the source vertex is not to be snapped? Tolerance cannot be obtained...
// and where should the post-collapse vertex be since we can't move the source vertex... // and where should the post-collapse vertex be since we can't move the source vertex...
// --> simply don't collapse? // --> simply don't collapse?
const FT min_tol = (std::min)(get(tolerance_map, vs), get(tolerance_map, vt)); const FT tol_s = get(tolerance_map, vs), tol_t = get(tolerance_map, vt);
const FT max_tol = (std::max)(get(tolerance_map, vs), get(tolerance_map, vt)); const FT max_tol = (std::max)(tol_s, tol_t);
if(gt.compare_squared_distance_3_object()(ps,pt,CGAL::square(max_tol))==SMALLER) if(gt.compare_squared_distance_3_object()(ps,pt,CGAL::square(max_tol)) == SMALLER)
{ {
const halfedge_descriptor prev_h = prev(h, tm); const halfedge_descriptor prev_h = prev(h, tm);
const halfedge_descriptor next_h = next(h, tm); const halfedge_descriptor next_h = next(h, tm);
@ -136,11 +137,23 @@ void simplify_range(HalfedgeRange& halfedge_range,
// check that the border has at least 4 edges not to create degenerate volumes // check that the border has at least 4 edges not to create degenerate volumes
if(border_size(h, tm) >= 4) if(border_size(h, tm) >= 4)
{ {
const FT h_sq_length = gt.compute_squared_distance_3_object()(ps, pt); const FT lambda = tol_s / (tol_s + tol_t);
vertex_descriptor v = Euler::collapse_edge(edge(h, tm), tm); const Point new_p = ps + lambda * (pt - ps);
put(vpm, v, gt.construct_midpoint_3_object()(ps, pt)); // If we're collapsing onto a vertex that is not allowed to move, keep it fixed
put(tolerance_map, v, min_tol + 0.5 * CGAL::approximate_sqrt(h_sq_length)); const FT min_tol = (std::min)(tol_s, tol_t);
FT new_tolerance = min_tol;
if(!is_zero(min_tol))
{
if(tol_t > tol_s) // the new point is closer to ps than to pt
new_tolerance += CGAL::approximate_sqrt(CGAL::squared_distance(new_p, ps));
else
new_tolerance += CGAL::approximate_sqrt(CGAL::squared_distance(new_p, pt));
}
vertex_descriptor v = Euler::collapse_edge(edge(h, tm), tm);
put(vpm, v, new_p);
put(tolerance_map, v, new_tolerance);
if(get(range_halfedges, prev_h)) if(get(range_halfedges, prev_h))
edges_to_test.insert(prev_h); edges_to_test.insert(prev_h);