Commit 5ee0b30d authored by Philip Trettner's avatar Philip Trettner
Browse files

generic edge split

parent a50e12bf
#pragma once
#include <queue>
#include <polymesh/Mesh.hh>
#include <polymesh/algorithms/properties.hh>
namespace polymesh
// PriorityF: (edge_handle) -> optional<T>
// (nullopt means edge should not be split, higher priorities are split first)
// SplitF: (vertex_handle v, halfedge_handle h, vertex_handle v_from, vertex_handle v_to, auto&& emit_edge) -> void
// (h is a new halfedge pointing to the new vertex v, but can be used to access the old attribute data as well)
// (emit_edge is edge_index -> void and must be called for any newly user-created edge.
// the two guaranteed new edges from the split are already added)
// NOTE: if mesh was compact before it is compact afterwards
template <class PriorityF, class SplitF>
void split_edges(Mesh& m, PriorityF&& priorityF, SplitF&& splitF)
using PrioT = std::decay_t<decltype(priorityF(pm::edge_handle{}).value())>;
struct entry
PrioT priority;
pm::edge_index edge;
bool operator<(entry const& rhs) const { return priority < rhs.priority; }
std::priority_queue<entry> queue;
auto const emit_edge = [&](edge_index new_e) {
if (auto p = priorityF(m[new_e]); p.has_value())
queue.push({p.value(), new_e});
// fill initial queue
for (auto e : m.edges())
// perform splits
while (!queue.empty())
edge_handle e = m[];
POLYMESH_ASSERT(e.is_valid() && !e.is_removed());
auto h = e.halfedgeA();
auto v_from = h.vertex_from();
auto v_to = h.vertex_to();
auto new_v = m.halfedges().split(h);
auto e0 = h.edge();
auto e1 =;
// split callback
splitF(new_v, h, v_from, v_to, emit_edge);
// same as split_edges but splitF has no emit_edge and triangle splits are performed
// the topology must not be altered in splitF
template <class PriorityF, class SplitF>
void split_edges_trimesh(Mesh& m, PriorityF&& priorityF, SplitF&& splitF)
split_edges(m, priorityF, [&](vertex_handle v_new, halfedge_handle h, vertex_handle v_from, vertex_handle v_to, auto&& emit_edge) {
auto ll = low_level_api(m);
edge_index new_edge_a;
edge_index new_edge_b;
if (v_new.is_boundary())
auto const f_new = m[ll.alloc_face()];
auto const e_new = m[ll.alloc_edge()];
auto const h0_new = e_new.halfedgeA();
auto const h1_new = e_new.halfedgeB();
auto const h_old = h.is_boundary() ? : h;
auto const f_old = h_old.face();
auto const v_opp = h_old.prev().vertex_from();
auto const h_f_new =;
// fix topo
ll.to_vertex_of(h0_new) = v_opp;
ll.to_vertex_of(h1_new) = v_new;
ll.halfedge_of(f_old) = h_old;
ll.halfedge_of(f_new) = h_f_new;
ll.face_of(h0_new) = f_old;
ll.face_of(h1_new) = f_new;
ll.face_of(h_f_new) = f_new;
ll.face_of( = f_new;
ll.connect_prev_next(h_old, h0_new);
ll.connect_prev_next(h1_new, h_f_new);
ll.connect_prev_next(h0_new, h_old.prev());
ll.connect_prev_next(, h1_new);
new_edge_a = e_new;
auto const f_0_new = m[ll.alloc_face()];
auto const f_1_new = m[ll.alloc_face()];
auto const e_0_new = m[ll.alloc_edge()];
auto const e_1_new = m[ll.alloc_edge()];
auto const h00 = e_0_new.halfedgeA();
auto const h01 = e_0_new.halfedgeB();
auto const h10 = e_1_new.halfedgeA();
auto const h11 = e_1_new.halfedgeB();
auto const f_0_old = h.face();
auto const f_1_old = h.opposite().face();
auto const v0 = h.prev().vertex_from();
auto const v1 = h.opposite().next().vertex_to();
auto const h_prev = h.prev();
auto const h_next =;
auto const h_next_opp = h_next.opposite();
auto const h_opp_next = h.opposite().next();
auto const h_next_next =;
auto const h_opp_next_next =;
// fix topo
ll.to_vertex_of(h00) = v0;
ll.to_vertex_of(h01) = v_new;
ll.to_vertex_of(h10) = v_new;
ll.to_vertex_of(h11) = v1;
ll.halfedge_of(f_0_old) = h_prev;
ll.halfedge_of(f_0_new) = h_next_next;
ll.halfedge_of(f_1_old) = h_opp_next;
ll.halfedge_of(f_1_new) = h_opp_next_next;
ll.face_of(h00) = f_0_old;
ll.face_of(h01) = f_0_new;
ll.face_of(h10) = f_1_old;
ll.face_of(h11) = f_1_new;
ll.face_of(h_next) = f_0_new;
ll.face_of(h_next_next) = f_0_new;
ll.face_of(h_next_opp) = f_1_new;
ll.face_of(h_opp_next_next) = f_1_new;
ll.connect_prev_next(h, h00);
ll.connect_prev_next(h00, h_prev);
ll.connect_prev_next(h_next_next, h01);
ll.connect_prev_next(h01, h_next);
ll.connect_prev_next(h_opp_next, h10);
ll.connect_prev_next(h10, h.opposite());
ll.connect_prev_next(h_next_opp, h11);
ll.connect_prev_next(h11, h_opp_next_next);
new_edge_a = e_0_new;
new_edge_b = e_1_new;
// user callback
splitF(v_new, h, v_from, v_to);
// emit edges
if (new_edge_a.is_valid())
if (new_edge_b.is_valid())
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