private static Shape makeLine(Vector2D base, Vector2D disp) {
double x1 = base.getX();
double y1 = base.getY();
double x2 = x1 + disp.getX();
double y2 = y1 + disp.getY();
return new Line2D.Double(x1, y1, x2, y2);
}
/**
* Get the bounding rectangle
*
* @return minimum bounding rectangle
*/
public BoundingRectangle2D getBounds() {
if (boundsChanged == true) {
boolean first = true;
double minX = 0;
double maxX = 0;
double minY = 0;
double maxY = 0;
for (Enumeration e = vertices.elements(); e.hasMoreElements(); ) {
Vector2D vertex = (Vector2D) e.nextElement();
if (first) {
minX = vertex.getX();
maxX = vertex.getX();
minY = vertex.getY();
maxY = vertex.getY();
first = false;
} else {
minX = Math.min(minX, vertex.getX());
maxX = Math.max(maxX, vertex.getX());
minY = Math.min(minY, vertex.getY());
maxY = Math.max(maxY, vertex.getY());
}
}
bounds.set(minX, minY, Math.abs(maxX - minX), Math.abs(maxY - minY));
boundsChanged = false;
}
return bounds;
}
/**
* Rotate the polygon clockwise about a point by an arbritray angle.
*
* @param x X ordinate of point to rotate about
* @param y Y ordinate of point to rotate about
* @param angle Angle in radians
*/
public void rotate(double x, double y, double angle) {
double theta = -angle;
for (Enumeration e = vertices(); e.hasMoreElements(); ) {
Vector2D vertex = (Vector2D) e.nextElement();
// translate to origin
double tmpX = vertex.getX() - x;
double tmpY = vertex.getY() - y;
// rotate
double sin = Math.sin(theta);
double cos = Math.cos(theta);
double newX = tmpX * cos - tmpY * sin;
double newY = tmpX * sin + tmpY * cos;
// translate back to old location
newX += x;
newY += y;
// set teh point to be where we calculated it should be
vertex.setXY(newX, newY);
}
flagModified();
}
/** Generate the edges of this polygon */
private void generateEdges() {
if (haveEdgesChanged == true) {
edges.removeAllElements();
Vector2D first = null;
Vector2D lastChecked = null;
double x = 0;
double y = 0;
for (Enumeration e = vertices.elements(); e.hasMoreElements(); ) {
Vector2D vertex = (Vector2D) e.nextElement();
x += vertex.getX();
y += vertex.getY();
if (lastChecked == null) {
first = vertex;
lastChecked = first;
} else {
edges.addElement(new Line2D(lastChecked, vertex));
lastChecked = vertex;
}
}
if (first != null) {
edges.addElement(new Line2D(lastChecked, first));
}
}
haveEdgesChanged = false;
}
/**
* Check if a point is contained within this polygon
*
* @param point
* @return true if contained, false otherwise
*/
public boolean contains(Vector2D point) {
if (!getBounds().contains(point)) {
System.out.println("AAA: " + point);
return false;
}
Line2D verticalRay = new Line2D(point, new Vector2D(point.getX(), Double.POSITIVE_INFINITY));
int intersectionCount = 0;
boolean contains = false;
generateEdges();
for (Enumeration e = edges.elements(); e.hasMoreElements(); ) {
Line2D testLine = (Line2D) e.nextElement();
double minY = Math.min(testLine.getStart().getY(), testLine.getEnd().getY());
double maxY = Math.max(testLine.getStart().getY(), testLine.getEnd().getY());
if (testLine.getGradient() == Double.POSITIVE_INFINITY) {
if (point.getX() == testLine.getStart().getX()
&& point.getY() >= minY
&& point.getY() <= maxY) {
contains = true;
}
} else {
if (verticalRay.intersects(testLine)) {
intersectionCount++;
}
}
}
return (contains || (intersectionCount % 2 == 1));
}
/**
* Translate the polygon by a vector offset
*
* @param offset
*/
public void translate(Vector2D offset) {
Enumeration e = vertices();
while (e.hasMoreElements()) {
Vector2D v = (Vector2D) e.nextElement();
v.add(offset);
}
flagModified();
}
/**
* Compute the (inward) normal of each node by taking a weighted average of the (inward) surface
* normals of the edges connected to it. Longer edges are given more weight.
*/
private void computeWeightedNormals() {
for (int i = 0, n = nodeList.size(); i < n; i++) {
Node prevNode = nodeList.get(i);
Node curNode = nodeList.get((i + 1) % n);
Node nextNode = nodeList.get((i + 2) % n);
Vector2D prevVector = curNode.getPosition().subtract(prevNode.getPosition()).rotate270();
Vector2D nextVector = nextNode.getPosition().subtract(curNode.getPosition()).rotate270();
normals.put(curNode, prevVector.add(nextVector).normalize());
}
}
private final void computeArea() {
// The area of a quadrilateral is 0.5*p*q*sin(theta)
// Where p and q are the length of the 2 diagonals and theta is the angle between them
// If we rotate P in the right direction, then area = 0.5*p*q*cos(theta) where theta is
// the angle between Q and the rotated P, but this is simply 0.5 * dot product of P' and Q
// Note, it is possible because of the cos to get a negative area, when this happens, it means
// that the quadrilateral has flipped and that the normally inward pointing normals are
// now pointing outward, so if we get a negative area, we should flip the force vectors...
Vector2D P = tv.getPosition().subtract(d.getPosition());
Vector2D Q = dt.getPosition().subtract(v.getPosition());
area = 0.5 * P.rotate90().dot(Q);
if (Math.signum(area) != Math.signum(desiredArea) && desiredArea != 0) {
System.err.println(
"Compartment:" + this.toString() + " has flipped inside out. Area:" + area);
}
}
/**
* Compute the (inward) normal at each node by averaging the unit direction vectors of the two
* edges connected to it.
*/
private void computeNormals() {
for (int i = 0, n = nodeList.size(); i < n; i++) {
Node prevNode = nodeList.get(i);
Node curNode = nodeList.get((i + 1) % n);
Node nextNode = nodeList.get((i + 2) % n);
Vector2D prevEdge = curNode.getPosition().subtract(prevNode.getPosition());
Vector2D nextEdge = nextNode.getPosition().subtract(curNode.getPosition());
double crossProd = prevEdge.crossMag(nextEdge);
Vector2D normal =
prevEdge.normalize().subtract(nextEdge.normalize()).scaleTo(Math.signum(crossProd));
normals.put(curNode, normal);
}
}
public void update() {
// See Compute Area for reason of the absolute value and signum of area...
double pressureForce =
Constants.get().getPressure() * (Math.abs(area) - Math.abs(desiredArea));
pressureForce =
Math.signum(area) * Math.signum(pressureForce) * Math.sqrt(Math.abs(pressureForce));
// The pressure is applied on every segment proportionally to its area.
for (int i = 0, n = nodeList.size(); i < n; i++) {
Node prevNode = nodeList.get(i);
Node curNode = nodeList.get((i + 1) % n);
Node nextNode = nodeList.get((i + 2) % n);
Vector2D prevVector = curNode.getPosition().subtract(prevNode.getPosition()).rotate270();
Vector2D nextVector = nextNode.getPosition().subtract(curNode.getPosition()).rotate270();
forces.put(curNode, prevVector.scale(pressureForce).add(nextVector.scale(pressureForce)));
}
}
/**
* Get the midpoint of this polygon
*
* @return Midpoint
*/
public Vector2D midPoint() {
if (isMidPointChanged == true) {
double x = 0;
double y = 0;
for (Enumeration e = vertices.elements(); e.hasMoreElements(); ) {
Vector2D vertex = (Vector2D) e.nextElement();
x += vertex.getX();
y += vertex.getY();
}
midPoint = new Vector2D(x / vertices.size(), y / vertices.size());
isMidPointChanged = false;
return midPoint;
} else {
return midPoint;
}
}
public void update() {
Vector2D prevVector = main.getPosition().subtract(previous.getPosition());
Vector2D nextVector = next.getPosition().subtract(main.getPosition());
double angleRad =
Math.acos(prevVector.dot(nextVector) / (prevVector.norm() * nextVector.norm()));
double angle = Math.toDegrees(angleRad);
if (prevVector.crossMag(nextVector) > 0) {
angle = 360.0 - angle;
}
double forceMag = ANGLE_CONSTANT * (angle - 90.0);
forces.put(previous, prevVector.rotate270().scaleTo(NEIGHBOR_ANGLE_SCALE * forceMag));
forces.put(main, normals.get(main).scaleTo(forceMag));
forces.put(next, nextVector.rotate270().scaleTo(NEIGHBOR_ANGLE_SCALE * forceMag));
}
/**
* Rotate the polygon clockwise about a point by an arbritray angle.
*
* @param v Point vector to rotate about
* @param angle Angle in radians
*/
public void rotate(Vector2D v, double angle) {
rotate(v.getX(), v.getY(), angle);
}