added add_or_get with edges

Readme.md

@@ -18,7 +18,7 @@ Best used with glm and glow.
 * smart ranges: filter, map
 * vector, set, map -> range
 * opposite edges (from vertex)
-* cotangens weights etc.
+* cotangents weights etc.
 * smoothing
 * make handle.<primitives>() contain only valid ones and provide an all_<primitives>() version
 * _copy versions of topological operations that copy attributes
@@ -28,4 +28,5 @@ Best used with glm and glow.
 * attribute iterator
 * primitive sort functions, better remap function, cache optimization
 * structure of arrays instead of AOS
-* lowlevel API that allows direct half-edge manipulation and does not fix boundaries (but also mirrors high level one)
\ No newline at end of file
+* lowlevel API that allows direct half-edge manipulation and does not fix boundaries (but also mirrors high level one)
+* primitive collection sort and sort_by functions
\ No newline at end of file

src/polymesh/Mesh.hh

@@ -161,9 +161,20 @@ private:
     /// Adds an edge between two existing, distinct vertices
     /// if edge already exists, returns it
     edge_index add_or_get_edge(vertex_index v_from, vertex_index v_to);
+    /// Adds an edge between to existing, distinct vertices that are pointed to by two given halfedges
+    /// if edge already exists, returns it
+    edge_index add_or_get_edge(halfedge_index h_from, halfedge_index h_to);
 
     /// same as add_or_get_edge but returns the apattrriate half-edge
+    /// Assures:
+    ///     return_value.from_vertex == v_from
+    ///     return_value.to_vertex == v_to
     halfedge_index add_or_get_halfedge(vertex_index v_from, vertex_index v_to);
+    /// same as add_or_get_edge but returns the apattrriate half-edge
+    /// Assures:
+    ///     return_value.from_vertex == h_from.to_vertex
+    ///     return_value.to_vertex == h_to.to_vertex
+    halfedge_index add_or_get_halfedge(halfedge_index h_from, halfedge_index h_to);
 
     /// connect two half-edges in a prev-next relation
     void connect_prev_next(halfedge_index prev, halfedge_index next);

src/polymesh/impl/impl_mesh.hh

@@ -213,6 +213,84 @@ inline halfedge_index Mesh::add_or_get_halfedge(vertex_index v_from, vertex_inde
     return halfedge(h0).to_vertex == v_to ? h0 : h1;
 }
 
+inline edge_index Mesh::add_or_get_edge(halfedge_index h_from, halfedge_index h_to)
+{
+    assert(h_from != h_to);
+    auto &hd_from = halfedge(h_from);
+    auto &hd_to = halfedge(h_to);
+
+    auto v_from = hd_from.to_vertex;
+    auto v_to = hd_to.to_vertex;
+
+    auto ex_he = find_halfedge(v_from, v_to);
+    if (ex_he.is_valid())
+    {
+        auto &existing_hed = halfedge(ex_he);
+        auto &ex_opp_hed = halfedge(opposite(ex_he));
+        assert(existing_hed.prev_halfedge == h_from && ex_opp_hed.prev_halfedge == h_to);
+        (void)existing_hed;
+        (void)ex_opp_hed;
+        // TODO: Maybe try rewriting an existing halfedge that does NOT yet have the right connection.
+        return edge_of(ex_he);
+    }
+
+    assert(hd_from.face.is_invalid() && hd_to.face.is_invalid() && "Cannot insert into a face");
+
+    // allocate new
+    auto he_size = (int)mHalfedges.size();
+    auto h_from_to_idx = halfedge_index(he_size + 0);
+    auto h_to_from_idx = halfedge_index(he_size + 1);
+    auto eidx = edge_index(he_size >> 1);
+    halfedge_info h_from_to;
+    halfedge_info h_to_from;
+
+    // setup data (self-connected edge)
+    h_from_to.to_vertex = v_to;
+    h_to_from.to_vertex = v_from;
+
+    // Link from side
+    auto h_from_next_idx = hd_from.next_halfedge;
+    auto &h_from_next = halfedge(h_from_next_idx);
+
+    hd_from.next_halfedge = h_from_to_idx;
+    h_from_to.prev_halfedge = h_from;
+
+    h_from_next.prev_halfedge = h_to_from_idx;
+    h_to_from.next_halfedge = h_from_next_idx;
+
+    // Link to side
+    auto h_to_next_idx = hd_to.next_halfedge;
+    auto &h_to_next = halfedge(h_to_next_idx);
+
+    hd_to.next_halfedge = h_to_from_idx;
+    h_to_from.prev_halfedge = h_to;
+
+    h_to_next.prev_halfedge = h_from_to_idx;
+    h_from_to.next_halfedge = h_to_next_idx;
+
+    // finalize
+    mHalfedges.push_back(h_from_to);
+    mHalfedges.push_back(h_to_from);
+
+    // notify attributes
+    auto hCnt = (int)mHalfedges.size();
+    auto eCnt = hCnt >> 1;
+    for (auto p = mHalfedgeAttrs; p; p = p->mNextAttribute)
+        p->resize(hCnt, false);
+    for (auto p = mEdgeAttrs; p; p = p->mNextAttribute)
+        p->resize(eCnt, false);
+
+    return eidx;
+}
+
+inline halfedge_index Mesh::add_or_get_halfedge(halfedge_index h_from, halfedge_index h_to)
+{
+    auto e = add_or_get_edge(h_from, h_to);
+    auto h0 = halfedge_of(e, 0);
+    auto h1 = halfedge_of(e, 1);
+    return halfedge(h_from).next_halfedge == h0 ? h0 : h1;
+}
+
 inline void Mesh::make_adjacent(halfedge_index he_in, halfedge_index he_out)
 {
     // see http://kaba.hilvi.org/homepage/blog/halfedge/halfedge.htm ::makeAdjacent

src/polymesh/impl/impl_ranges.hh

@@ -687,6 +687,18 @@ halfedge_handle halfedge_collection<iterator>::add_or_get(vertex_handle v_from,
     return this->mesh->handle_of(this->mesh->add_or_get_halfedge(v_from.idx, v_to.idx));
 }
 
+template <class iterator>
+edge_handle edge_collection<iterator>::add_or_get(halfedge_handle h_from, halfedge_handle h_to) const
+{
+    return this->mesh->handle_of(this->mesh->add_or_get_edge(h_from.idx, h_to.idx));
+}
+
+template <class iterator>
+halfedge_handle halfedge_collection<iterator>::add_or_get(halfedge_handle h_from, halfedge_handle h_to) const
+{
+    return this->mesh->handle_of(this->mesh->add_or_get_halfedge(h_from.idx, h_to.idx));
+}
+
 template <class iterator>
 edge_handle edge_collection<iterator>::find(vertex_handle v_from, vertex_handle v_to) const
 {

src/polymesh/ranges.hh

@@ -253,6 +253,9 @@ struct edge_collection : smart_collection<Mesh*, edge_tag, iterator>
     /// Adds an edge between two existing, distinct vertices
     /// if edge already exists, returns it
     edge_handle add_or_get(vertex_handle v_from, vertex_handle v_to) const;
+    /// Adds an edge between two existing, distict halfedges
+    /// if edge already exists, returns it
+    edge_handle add_or_get(halfedge_handle h_from, halfedge_handle h_to) const;
 
     /// Returns the edge handle between two vertices (invalid if not found)
     /// O(valence) computation
@@ -291,6 +294,10 @@ struct halfedge_collection : smart_collection<Mesh*, halfedge_tag, iterator>
     /// if half-edge already exists, returns it
     /// (always adds opposite half-edge as well)
     halfedge_handle add_or_get(vertex_handle v_from, vertex_handle v_to) const;
+    /// Adds an half-edge between two existing, distinct hafledges
+    /// if half-edge already exists, returns it
+    /// (always adds opposite half-edge as well)
+    halfedge_handle add_or_get(halfedge_handle h_from, halfedge_handle h_to) const;
 
     /// Returns the half-edge handle between two vertices (invalid if not found)
     /// O(valence) computation