public int mergeAdjacentFace(HalfEdge hedgeAdj, Face[] discarded) {
Face oppFace = hedgeAdj.oppositeFace();
int numDiscarded = 0;
discarded[numDiscarded++] = oppFace;
oppFace.mark = DELETED;
HalfEdge hedgeOpp = hedgeAdj.getOpposite();
HalfEdge hedgeAdjPrev = hedgeAdj.prev;
HalfEdge hedgeAdjNext = hedgeAdj.next;
HalfEdge hedgeOppPrev = hedgeOpp.prev;
HalfEdge hedgeOppNext = hedgeOpp.next;
while (hedgeAdjPrev.oppositeFace() == oppFace) {
hedgeAdjPrev = hedgeAdjPrev.prev;
hedgeOppNext = hedgeOppNext.next;
}
while (hedgeAdjNext.oppositeFace() == oppFace) {
hedgeOppPrev = hedgeOppPrev.prev;
hedgeAdjNext = hedgeAdjNext.next;
}
HalfEdge hedge;
for (hedge = hedgeOppNext; hedge != hedgeOppPrev.next; hedge = hedge.next) {
hedge.face = this;
}
if (hedgeAdj == he0) {
he0 = hedgeAdjNext;
}
// handle the half edges at the head
Face discardedFace;
discardedFace = connectHalfEdges(hedgeOppPrev, hedgeAdjNext);
if (discardedFace != null) {
discarded[numDiscarded++] = discardedFace;
}
// handle the half edges at the tail
discardedFace = connectHalfEdges(hedgeAdjPrev, hedgeOppNext);
if (discardedFace != null) {
discarded[numDiscarded++] = discardedFace;
}
computeNormalAndCentroid();
checkConsistency();
return numDiscarded;
}
private Face connectHalfEdges(HalfEdge hedgePrev, HalfEdge hedge) {
Face discardedFace = null;
if (hedgePrev.oppositeFace()
== hedge.oppositeFace()) { // then there is a redundant edge that we can get rid off
Face oppFace = hedge.oppositeFace();
HalfEdge hedgeOpp;
if (hedgePrev == he0) {
he0 = hedge;
}
if (oppFace.numVertices() == 3) { // then we can get rid of the opposite face altogether
hedgeOpp = hedge.getOpposite().prev.getOpposite();
oppFace.mark = DELETED;
discardedFace = oppFace;
} else {
hedgeOpp = hedge.getOpposite().next;
if (oppFace.he0 == hedgeOpp.prev) {
oppFace.he0 = hedgeOpp;
}
hedgeOpp.prev = hedgeOpp.prev.prev;
hedgeOpp.prev.next = hedgeOpp;
}
hedge.prev = hedgePrev.prev;
hedge.prev.next = hedge;
hedge.opposite = hedgeOpp;
hedgeOpp.opposite = hedge;
// oppFace was modified, so need to recompute
oppFace.computeNormalAndCentroid();
} else {
hedgePrev.next = hedge;
hedge.prev = hedgePrev;
}
return discardedFace;
}