/**
* Report neighbor opposite the given vertex of triangle.
*
* @param site a vertex of triangle
* @param triangle we want the neighbor of this triangle
* @return the neighbor opposite site in triangle; null if none
* @throws IllegalArgumentException if site is not in this triangle
*/
public Triangle neighborOpposite(Pnt site, Triangle triangle) {
if (!triangle.contains(site))
throw new IllegalArgumentException("Bad vertex; not in triangle");
for (Triangle neighbor : triGraph.neighbors(triangle)) {
if (!neighbor.contains(site)) return neighbor;
}
return null;
}
/**
* Place a new site into the DT. Nothing happens if the site matches an existing DT vertex.
*
* @param site the new Pnt
* @throws IllegalArgumentException if site does not lie in any triangle
*/
public void delaunayPlace(Pnt site) {
// Uses straightforward scheme rather than best
// asymptotic time
// Locate containing triangle
Triangle triangle = locate(site);
// Give up if no containing triangle or if site is
// already in DT
if (triangle == null) throw new IllegalArgumentException("No containing triangle");
if (triangle.contains(site)) return;
// Determine the cavity and update the triangulation
Set<Triangle> cavity = getCavity(site, triangle);
lastCavity = cavity;
mostRecent = update(site, cavity);
}
/**
* Report triangles surrounding site in order (cw or ccw).
*
* @param site we want the surrounding triangles for this site
* @param triangle a "starting" triangle that has site as a vertex
* @return all triangles surrounding site in order (cw or ccw)
* @throws IllegalArgumentException if site is not in triangle
*/
public List<Triangle> surroundingTriangles(Pnt site, Triangle triangle) {
if (!triangle.contains(site)) throw new IllegalArgumentException("Site not in triangle");
List<Triangle> list = new ArrayList<Triangle>();
Triangle start = triangle;
Pnt guide = triangle.getVertexButNot(site); // Affects
// cw or
// ccw
while (true) {
list.add(triangle);
Triangle previous = triangle;
; // System.out.println(" site :" + site + " " + guide + " " + triangle);
if (triangle == null) break;
triangle = this.neighborOpposite(guide, triangle); // Next
// triangle
guide = previous.getVertexButNot(site, guide); // Update
// guide
if (triangle == start) break;
}
return list;
}
/**
* True iff triangles are neighbors. Two triangles are neighbors if they share a facet.
*
* @param triangle the other Triangle
* @return true iff this Triangle is a neighbor of triangle
*/
public boolean isNeighbor(Triangle triangle) {
int count = 0;
for (Pnt vertex : this) if (!triangle.contains(vertex)) count++;
return count == 1;
}
