public String getVertexString() {
String s = null;
HalfEdge he = he0;
do {
if (s == null) {
s = "" + he.head().index;
} else {
s += " " + he.head().index;
}
he = he.next;
} while (he != he0);
return s;
}
public void computeNormal(Vector3d normal, double minArea) {
computeNormal(normal);
if (area < minArea) {
System.out.println("area=" + area);
// make the normal more robust by removing
// components parallel to the longest edge
HalfEdge hedgeMax = null;
double lenSqrMax = 0;
HalfEdge hedge = he0;
do {
double lenSqr = hedge.lengthSquared();
if (lenSqr > lenSqrMax) {
hedgeMax = hedge;
lenSqrMax = lenSqr;
}
hedge = hedge.next;
} while (hedge != he0);
Point3d p2 = hedgeMax.head().pnt;
Point3d p1 = hedgeMax.tail().pnt;
double lenMax = Math.sqrt(lenSqrMax);
double ux = (p2.x - p1.x) / lenMax;
double uy = (p2.y - p1.y) / lenMax;
double uz = (p2.z - p1.z) / lenMax;
double dot = normal.x * ux + normal.y * uy + normal.z * uz;
normal.x -= dot * ux;
normal.y -= dot * uy;
normal.z -= dot * uz;
normal.normalize();
}
}
public void getVertexIndices(int[] idxs) {
HalfEdge he = he0;
int i = 0;
do {
idxs[i++] = he.head().index;
he = he.next;
} while (he != he0);
}
public void computeCentroid(Point3d centroid) {
centroid.setZero();
HalfEdge he = he0;
do {
centroid.add(he.head().pnt);
he = he.next;
} while (he != he0);
centroid.scale(1 / (double) numVerts);
}
/**
* Finds the half-edge within this face which has tail <code>vt</code> and head <code>vh</code>.
*
* @param vt tail point
* @param vh head point
* @return the half-edge, or null if none is found.
*/
public HalfEdge findEdge(Vertex vt, Vertex vh) {
HalfEdge he = he0;
do {
if (he.head() == vh && he.tail() == vt) {
return he;
}
he = he.next;
} while (he != he0);
return null;
}
public void triangulate(FaceList newFaces, double minArea) {
HalfEdge hedge;
if (numVertices() < 4) {
return;
}
Vertex v0 = he0.head();
Face prevFace = null;
hedge = he0.next;
HalfEdge oppPrev = hedge.opposite;
Face face0 = null;
for (hedge = hedge.next; hedge != he0.prev; hedge = hedge.next) {
Face face = createTriangle(v0, hedge.prev.head(), hedge.head(), minArea);
face.he0.next.setOpposite(oppPrev);
face.he0.prev.setOpposite(hedge.opposite);
oppPrev = face.he0;
newFaces.add(face);
if (face0 == null) {
face0 = face;
}
}
hedge = new HalfEdge(he0.prev.prev.head(), this);
hedge.setOpposite(oppPrev);
hedge.prev = he0;
hedge.prev.next = hedge;
hedge.next = he0.prev;
hedge.next.prev = hedge;
computeNormalAndCentroid(minArea);
checkConsistency();
for (Face face = face0; face != null; face = face.next) {
face.checkConsistency();
}
}
private double areaSquared(HalfEdge hedge0, HalfEdge hedge1) {
// return the squared area of the triangle defined
// by the half edge hedge0 and the point at the
// head of hedge1.
Point3d p0 = hedge0.tail().pnt;
Point3d p1 = hedge0.head().pnt;
Point3d p2 = hedge1.head().pnt;
double dx1 = p1.x - p0.x;
double dy1 = p1.y - p0.y;
double dz1 = p1.z - p0.z;
double dx2 = p2.x - p0.x;
double dy2 = p2.y - p0.y;
double dz2 = p2.z - p0.z;
double x = dy1 * dz2 - dz1 * dy2;
double y = dz1 * dx2 - dx1 * dz2;
double z = dx1 * dy2 - dy1 * dx2;
return x * x + y * y + z * z;
}
public void computeNormal(Vector3d normal) {
HalfEdge he1 = he0.next;
HalfEdge he2 = he1.next;
Point3d p0 = he0.head().pnt;
Point3d p2 = he1.head().pnt;
double d2x = p2.x - p0.x;
double d2y = p2.y - p0.y;
double d2z = p2.z - p0.z;
normal.setZero();
numVerts = 2;
while (he2 != he0) {
double d1x = d2x;
double d1y = d2y;
double d1z = d2z;
p2 = he2.head().pnt;
d2x = p2.x - p0.x;
d2y = p2.y - p0.y;
d2z = p2.z - p0.z;
normal.x += d1y * d2z - d1z * d2y;
normal.y += d1z * d2x - d1x * d2z;
normal.z += d1x * d2y - d1y * d2x;
he1 = he2;
he2 = he2.next;
numVerts++;
}
area = normal.norm();
normal.scale(1 / area);
}
void checkConsistency() {
// do a sanity check on the face
HalfEdge hedge = he0;
double maxd = 0;
int numv = 0;
if (numVerts < 3) {
throw new InternalErrorException("degenerate face: " + getVertexString());
}
do {
HalfEdge hedgeOpp = hedge.getOpposite();
if (hedgeOpp == null) {
throw new InternalErrorException(
"face "
+ getVertexString()
+ ": "
+ "unreflected half edge "
+ hedge.getVertexString());
} else if (hedgeOpp.getOpposite() != hedge) {
throw new InternalErrorException(
"face "
+ getVertexString()
+ ": "
+ "opposite half edge "
+ hedgeOpp.getVertexString()
+ " has opposite "
+ hedgeOpp.getOpposite().getVertexString());
}
if (hedgeOpp.head() != hedge.tail() || hedge.head() != hedgeOpp.tail()) {
throw new InternalErrorException(
"face "
+ getVertexString()
+ ": "
+ "half edge "
+ hedge.getVertexString()
+ " reflected by "
+ hedgeOpp.getVertexString());
}
Face oppFace = hedgeOpp.face;
if (oppFace == null) {
throw new InternalErrorException(
"face "
+ getVertexString()
+ ": "
+ "no face on half edge "
+ hedgeOpp.getVertexString());
} else if (oppFace.mark == DELETED) {
throw new InternalErrorException(
"face "
+ getVertexString()
+ ": "
+ "opposite face "
+ oppFace.getVertexString()
+ " not on hull");
}
double d = Math.abs(distanceToPlane(hedge.head().pnt));
if (d > maxd) {
maxd = d;
}
numv++;
hedge = hedge.next;
} while (hedge != he0);
if (numv != numVerts) {
throw new InternalErrorException(
"face " + getVertexString() + " numVerts=" + numVerts + " should be " + numv);
}
}