/**
* Computes the 3D area of a triangle based on the same approach of JTS
*
* @return
*/
public final double getArea3D() {
DPoint p1, p2, pptNb;
p1 = edges[0].getStartPoint();
p2 = edges[0].getEndPoint();
pptNb = edges[1].getStartPoint();
if ((pptNb.equals(p1)) || (pptNb.equals(p2))) {
pptNb = edges[1].getEndPoint();
}
/**
* Uses the formula 1/2 * | u x v | where u,v are the side vectors of the triangle x is the
* vector cross-product
*/
// side vectors u and v
double ux = p2.getX() - p1.getX();
double uy = p2.getY() - p1.getY();
double uz = p2.getZ() - p1.getZ();
double vx = pptNb.getX() - p1.getX();
double vy = pptNb.getY() - p1.getY();
double vz = pptNb.getZ() - p1.getZ();
// cross-product = u x v
double crossx = uy * vz - uz * vy;
double crossy = uz * vx - ux * vz;
double crossz = ux * vy - uy * vx;
// tri area = 1/2 * | u x v |
double absSq = crossx * crossx + crossy * crossy + crossz * crossz;
return Math.sqrt(absSq) / 2;
}
/**
* Get Z value of a specific point in the triangle
*
* @param aPoint
* @return ZValue
*/
public final double interpolateZ(DPoint aPoint) {
double zValue = 0;
DPoint p1, p2, p3;
p1 = edges[0].getStartPoint();
p2 = edges[0].getEndPoint();
p3 = edges[1].getStartPoint();
if ((p3.equals(p1)) || (p3.equals(p2))) {
p3 = edges[1].getEndPoint();
}
double ux = p2.getX() - p1.getX();
double uy = p2.getY() - p1.getY();
double uz = p2.getZ() - p1.getZ();
double vx = p3.getX() - p1.getX();
double vy = p3.getY() - p1.getY();
double vz = p3.getZ() - p1.getZ();
double a = uy * vz - uz * vy;
double b = uz * vx - ux * vz;
double c = ux * vy - uy * vx;
double d = -a * p1.getX() - b * p1.getY() - c * p1.getZ();
if (Math.abs(c) > Tools.EPSILON) {
// Non vertical triangle
zValue = (-a * aPoint.getX() - b * aPoint.getY() - d) / c;
}
return zValue;
}
/**
* Get the point of the triangle that is not one of the 2 points given in argument. If one of
* these argument is not part of this triangle, this method will return null.
*
* @param p1
* @param p2
* @return alterPoint
*/
public final DPoint getAlterPoint(DPoint p1, DPoint p2) {
DPoint t1 = getPoint(0);
DPoint t2 = getPoint(1);
DPoint t3 = getPoint(2);
if (p1.equals(t1)) {
if (p2.equals(t2)) {
return t3;
} else if (p2.equals(t3)) {
return t2;
}
} else if (p1.equals(t2)) {
if (p2.equals(t1)) {
return t3;
} else if (p2.equals(t3)) {
return t1;
}
} else if (p1.equals(t3)) {
if (p2.equals(t1)) {
return t2;
} else if (p2.equals(t2)) {
return t1;
}
}
return null;
}
/**
* Get the ith point. i must be equal to 0, 1 or 2.
*
* <p>This method is consistent with getPoints, ie getPoints().get(i)==getPoint(i).
*
* @param i
* @return aPoint On of the apex if i = 0, 1 or 2, null otherwise.
*/
public final DPoint getPoint(int i) {
DPoint p = null;
if (i == 0) {
p = edges[0].getStartPoint();
} else if (i == 1) {
p = edges[0].getEndPoint();
} else if (i == 2) {
p = edges[1].getStartPoint();
if ((p.equals(edges[0].getStartPoint())) || (p.equals(edges[0].getEndPoint()))) {
p = edges[1].getEndPoint();
}
}
return p;
}
/**
* Compute triangle area
*
* @return area
*/
public final double getArea() {
DPoint p1, p2, pptNb;
p1 = edges[0].getStartPoint();
p2 = edges[0].getEndPoint();
pptNb = edges[1].getStartPoint();
if ((pptNb.equals(p1)) || (pptNb.equals(p2))) {
pptNb = edges[1].getEndPoint();
}
double area =
((pptNb.getX() - p1.getX()) * (p2.getY() - p1.getY())
- (p2.getX() - p1.getX()) * (pptNb.getY() - p1.getY()))
/ 2;
return area < 0 ? -area : area;
}
@Override
public final BoundaryBox getBoundingBox() throws DelaunayError {
BoundaryBox aBox = new BoundaryBox();
DPoint p1, p2, pptNb;
p1 = edges[0].getStartPoint();
p2 = edges[0].getEndPoint();
pptNb = edges[1].getStartPoint();
if ((pptNb.equals(p1)) || (pptNb.equals(p2))) {
pptNb = edges[1].getEndPoint();
}
aBox.alterBox(p1);
aBox.alterBox(p2);
aBox.alterBox(pptNb);
return aBox;
}
/**
* Recompute the center of the circle that joins the ptNb points : the CircumCenter
*
* @throws DelaunayError
*/
public final void computeCenter() throws DelaunayError {
DPoint p1, p2, pptNb;
p1 = edges[0].getStartPoint();
p2 = edges[0].getEndPoint();
pptNb = edges[1].getStartPoint();
if ((pptNb.equals(p1)) || (pptNb.equals(p2))) {
pptNb = edges[1].getEndPoint();
}
double p1Sq = p1.getX() * p1.getX() + p1.getY() * p1.getY();
double p2Sq = p2.getX() * p2.getX() + p2.getY() * p2.getY();
double pptNbSq = pptNb.getX() * pptNb.getX() + pptNb.getY() * pptNb.getY();
double ux = p2.getX() - p1.getX();
double uy = p2.getY() - p1.getY();
double vx = pptNb.getX() - p1.getX();
double vy = pptNb.getY() - p1.getY();
double cp = ux * vy - uy * vx;
double cx, cy;
if (cp != 0) {
cx =
(p1Sq * (p2.getY() - pptNb.getY())
+ p2Sq * (pptNb.getY() - p1.getY())
+ pptNbSq * (p1.getY() - p2.getY()))
/ (2.0 * cp);
cy =
(p1Sq * (pptNb.getX() - p2.getX())
+ p2Sq * (p1.getX() - pptNb.getX())
+ pptNbSq * (p2.getX() - p1.getX()))
/ (2.0 * cp);
xCenter = cx;
yCenter = cy;
zCenter = interpolateZ(new DPoint(cx, cy, 0));
radius = p1.squareDistance2D(xCenter, yCenter);
} else {
xCenter = 0.0;
yCenter = 0.0;
radius = -1;
}
}
/**
* Get the edge of the triangle that includes the two point
*
* @param p1
* @param p2
* @return alterEdge
*/
protected final DEdge getEdgeFromPoints(DPoint p1, DPoint p2) {
DEdge alterEdge = null;
DPoint test1, test2;
int i = 0;
while (i < PT_NB && alterEdge == null) {
DEdge testEdge = edges[i];
test1 = testEdge.getStartPoint();
test2 = testEdge.getEndPoint();
if ((test1.equals(p1)) && (test2.equals(p2))) {
alterEdge = testEdge;
} else if ((test1.equals(p2)) && (test2.equals(p1))) {
alterEdge = testEdge;
} else {
i++;
}
}
return alterEdge;
}
