void ExtremalQuery3BSP<Real>::SortVertexAdjacents (BasicMesh& mesh)
{
// The typecast is to allow modifying the vertices. As long as the
// sorting algorithm is correct, this is a safe thing to do.
int numVertices = mesh.GetNumVertices();
BasicMesh::Vertex* vertices = (BasicMesh::Vertex*)mesh.GetVertices();
const BasicMesh::Triangle* triangles = mesh.GetTriangles();
for (int i = 0; i < numVertices; ++i)
{
// This copy circumvents the constness of the mesh vertices, which
// allows the sorting of the mesh triangles shared by a mesh vertex.
BasicMesh::Vertex& vertex = vertices[i];
// This is a consequence of the mesh being a polyhedron.
assertion(vertex.NumVertices == vertex.NumTriangles,
"Unexpected condition\n");
// Once we have the first vertex to sort and an initial triangle
// sharing it, we can walk around the vertex following triangle
// adjacency links. It is safe to overwrite the vertex data.
int t = vertex.T[0];
const BasicMesh::Triangle* tri = &triangles[t];
for (int adj = 0; adj < vertex.NumVertices; ++adj)
{
int prev, curr;
for (prev = 2, curr = 0; curr < 3; prev = curr++)
{
if (tri->V[curr] == i)
{
vertex.V[adj] = tri->V[prev];
vertex.E[adj] = tri->E[prev];
vertex.T[adj] = t;
// The next triangle to visit.
t = tri->T[prev];
tri = &triangles[t];
break;
}
}
assertion(curr < 3, "Unexpected condition\n");
}
}
}
void ExtremalQuery3BSP<Real>::CreateSphericalArcs (BasicMesh& mesh,
std::multiset<SphericalArc>& arcs)
{
int numEdges = mesh.GetNumEdges();
const BasicMesh::Edge* edges = mesh.GetEdges();
const BasicMesh::Triangle* triangles = mesh.GetTriangles();
const int prev[3] = { 2, 0, 1 };
const int next[3] = { 1, 2, 0 };
for (int i = 0; i < numEdges; ++i)
{
const BasicMesh::Edge& edge = edges[i];
SphericalArc arc;
arc.NIndex[0] = edge.T[0];
arc.NIndex[1] = edge.T[1];
arc.Separation = 1;
arc.Normal = mFaceNormals[arc.NIndex[0]].Cross(
mFaceNormals[arc.NIndex[1]]);
const BasicMesh::Triangle& adj = triangles[edge.T[0]];
int j;
for (j = 0; j < 3; ++j)
{
if (adj.V[j] != edge.V[0]
&& adj.V[j] != edge.V[1])
{
arc.PosVertex = adj.V[prev[j]];
arc.NegVertex = adj.V[next[j]];
break;
}
}
assertion(j < 3, "Unexpected condition\n");
arcs.insert(arc);
}
CreateSphericalBisectors(mesh, arcs);
}