From f64d95b5cbdcbfe3b1ecb7ff27e931e988f0c1ae Mon Sep 17 00:00:00 2001
From: Philip Trettner <Philip.Trettner@rwth-aachen.de>
Date: Tue, 3 Dec 2019 18:56:15 +0100
Subject: [PATCH] fixed collapse_halfedge for many cases
---
src/polymesh/algorithms/properties.hh | 1 +
.../impl/impl_low_level_api_mutable.hh | 212 +++++++++++++-----
2 files changed, 162 insertions(+), 51 deletions(-)
diff --git a/src/polymesh/algorithms/properties.hh b/src/polymesh/algorithms/properties.hh
index 7b6988b..f5be01b 100644
--- a/src/polymesh/algorithms/properties.hh
+++ b/src/polymesh/algorithms/properties.hh
@@ -606,6 +606,7 @@ inline bool can_collapse(halfedge_handle h)
if (v == ignore_v0 || v == ignore_v1 || v == v_from)
continue;
+ // TODO: can be made faster by buffering these vertices
if (v_from.adjacent_vertices().contains(v))
return false;
}
diff --git a/src/polymesh/impl/impl_low_level_api_mutable.hh b/src/polymesh/impl/impl_low_level_api_mutable.hh
index bac58a5..7059f61 100644
--- a/src/polymesh/impl/impl_low_level_api_mutable.hh
+++ b/src/polymesh/impl/impl_low_level_api_mutable.hh
@@ -793,9 +793,6 @@ inline void low_level_api_mutable::halfedge_collapse(halfedge_index h) const
auto h0 = h;
auto h1 = opposite(h);
- POLYMESH_ASSERT(!is_boundary(h0) && "boundaries are not supported yet");
- POLYMESH_ASSERT(!is_boundary(h1) && "boundaries are not supported yet");
-
auto v_to = to_vertex_of(h);
auto v_from = from_vertex_of(h);
@@ -807,58 +804,171 @@ inline void low_level_api_mutable::halfedge_collapse(halfedge_index h) const
auto h1_prev = prev_halfedge_of(h1);
auto h1_next = next_halfedge_of(h1);
- // TODO: preserve adjacent non-triangles
- POLYMESH_ASSERT(prev_halfedge_of(h0_prev) == h0_next && "non-triangle adjacent faces not supported yet");
- POLYMESH_ASSERT(prev_halfedge_of(h1_prev) == h1_next && "non-triangle adjacent faces not supported yet");
+ auto is_to_wrapped = h0_next == h1;
+ auto is_from_wrapped = h1_next == h0;
- // fix faces
- auto h0_prev_opp = opposite(h0_prev);
- auto h1_next_opp = opposite(h1_next);
- auto fA = face_of(h0_prev_opp);
- auto fB = face_of(h1_next_opp);
- face_of(h0_next) = fA;
- face_of(h1_prev) = fB;
- if (halfedge_of(fA) == h0_prev_opp)
- halfedge_of(fA) = h0_next;
- if (halfedge_of(fB) == h1_next_opp)
- halfedge_of(fB) = h1_prev;
+ auto is_h0_boundary = is_boundary(h0);
+ auto is_h1_boundary = is_boundary(h1);
- // fix vertices
- auto hv = h1;
- do
+ auto is_h0_triangle = !is_h0_boundary && next_halfedge_of(h0_next) == h0_prev;
+ auto is_h1_triangle = !is_h1_boundary && next_halfedge_of(h1_next) == h1_prev;
+
+ auto is_valence_2_from = h0_prev == opposite(h1_next);
+
+ // special cases for self-connected edges
+ if (is_to_wrapped && is_from_wrapped) // complete wraparound
{
- // point to collapsed vertex
- POLYMESH_ASSERT(to_vertex_of(hv) == v_from);
- to_vertex_of(hv) = v_to;
+ POLYMESH_ASSERT(f0.is_invalid() && "self-connected cannot have face");
+ POLYMESH_ASSERT(f1.is_invalid() && "self-connected cannot have face");
- // advance
- hv = opposite(next_halfedge_of(hv));
- } while (hv != h1);
-
- if (outgoing_halfedge_of(v_to) == h1)
- outgoing_halfedge_of(v_to) = h0_next;
-
- auto vA = to_vertex_of(h0_next);
- auto vB = to_vertex_of(h1_next);
- if (outgoing_halfedge_of(vA) == h0_prev)
- outgoing_halfedge_of(vA) = next_halfedge_of(h0_prev_opp);
- if (outgoing_halfedge_of(vB) == h1_next_opp)
- outgoing_halfedge_of(vB) = h1_prev;
-
- // fix next-prev
- connect_prev_next(h1_prev, next_halfedge_of(h1_next_opp));
- connect_prev_next(prev_halfedge_of(h1_next_opp), h1_prev);
-
- connect_prev_next(h0_next, next_halfedge_of(h0_prev_opp));
- connect_prev_next(prev_halfedge_of(h0_prev_opp), h0_next);
-
- // mark for deletion
- set_removed(v_from);
- set_removed(f0);
- set_removed(f1);
- set_removed(edge_of(h));
- set_removed(edge_of(h0_prev));
- set_removed(edge_of(h1_next));
+ outgoing_halfedge_of(v_to) = halfedge_index::invalid;
+
+ set_removed(v_from);
+ set_removed(edge_of(h));
+ }
+ else if (is_from_wrapped) // from is self-connected
+ {
+ POLYMESH_ASSERT(f0 == f1 && "how can they have different faces?");
+
+ connect_prev_next(h1_prev, h0_next);
+ auto& oh = outgoing_halfedge_of(v_to);
+ if (oh == h1)
+ oh = h0_next;
+
+ if (f0.is_valid())
+ {
+ auto& fh = halfedge_of(f0);
+ if (fh == h0 || fh == h1)
+ fh = h0_next;
+ }
+
+ set_removed(v_from);
+ set_removed(edge_of(h));
+ }
+ else if (is_to_wrapped) // to is self-connected
+ {
+ POLYMESH_ASSERT(f0 == f1 && "how can they have different faces?");
+
+ connect_prev_next(h0_prev, h1_next);
+ outgoing_halfedge_of(v_to) = h1_next;
+
+ auto h = opposite(h1_next);
+ while (h != h1)
+ {
+ to_vertex_of(h) = v_to;
+ h = opposite(next_halfedge_of(h));
+ }
+
+ if (f0.is_valid())
+ {
+ auto& fh = halfedge_of(f0);
+ if (fh == h0 || fh == h1)
+ fh = h0_next;
+ }
+
+ fix_boundary_state_of(v_to);
+
+ set_removed(v_from);
+ set_removed(edge_of(h));
+ }
+ else
+ {
+ auto h0_prev_opp = opposite(h0_prev);
+ auto h1_next_opp = opposite(h1_next);
+
+ // fix faces (only if triangle because then the triangle is removed)
+ if (is_h0_triangle)
+ {
+ auto fA = face_of(h0_prev_opp);
+
+ face_of(h0_next) = fA;
+
+ if (fA.is_valid() && halfedge_of(fA) == h0_prev_opp)
+ halfedge_of(fA) = h0_next;
+ }
+ if (is_h1_triangle)
+ {
+ auto fB = face_of(h1_next_opp);
+
+ face_of(h1_prev) = fB;
+
+ if (fB.is_valid() && halfedge_of(fB) == h1_next_opp)
+ halfedge_of(fB) = h1_prev;
+ }
+
+ // fix vertices
+ auto hv = h1;
+ do
+ {
+ // point to collapsed vertex
+ POLYMESH_ASSERT(to_vertex_of(hv) == v_from);
+ to_vertex_of(hv) = v_to;
+
+ // advance
+ hv = opposite(next_halfedge_of(hv));
+ } while (hv != h1);
+
+ // fix outgoing of v_to
+ if (outgoing_halfedge_of(v_to) == h1)
+ outgoing_halfedge_of(v_to) = h0_next;
+
+ // fix outgoing of opposite of h0/h1 (if triangle) and prev/next
+ if (is_h0_triangle)
+ {
+ auto vA = to_vertex_of(h0_next);
+ if (outgoing_halfedge_of(vA) == h0_prev)
+ outgoing_halfedge_of(vA) = next_halfedge_of(h0_prev_opp);
+
+ // fix next-prev
+ connect_prev_next(h0_next, next_halfedge_of(h0_prev_opp));
+ if (is_valence_2_from)
+ connect_prev_next(prev_halfedge_of(prev_halfedge_of(h0_prev_opp)), h0_next);
+ else
+ connect_prev_next(prev_halfedge_of(h0_prev_opp), h0_next);
+ }
+ else
+ {
+ if (!is_valence_2_from)
+ connect_prev_next(h0_prev, h0_next);
+ }
+ if (is_h1_triangle)
+ {
+ auto vB = to_vertex_of(h1_next);
+ if (outgoing_halfedge_of(vB) == h1_next_opp)
+ outgoing_halfedge_of(vB) = h1_prev;
+
+ // fix next-prev
+ if (is_valence_2_from)
+ connect_prev_next(h1_prev, next_halfedge_of(next_halfedge_of(h1_next_opp)));
+ else
+ connect_prev_next(h1_prev, next_halfedge_of(h1_next_opp));
+ connect_prev_next(prev_halfedge_of(h1_next_opp), h1_prev);
+ }
+ else
+ {
+ if (is_valence_2_from)
+ connect_prev_next(h1_prev, h0_next);
+ else
+ connect_prev_next(h1_prev, h1_next);
+ }
+
+ // vertex might be boundary now
+ fix_boundary_state_of(v_to);
+
+ // mark for deletion
+ set_removed(v_from);
+ set_removed(edge_of(h));
+ if (is_h0_triangle)
+ {
+ set_removed(f0);
+ set_removed(edge_of(h0_prev));
+ }
+ if (is_h1_triangle)
+ {
+ set_removed(f1);
+ set_removed(edge_of(h1_next));
+ }
+ }
}
inline void low_level_api_mutable::edge_rotate_next(edge_index e) const
--
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