/**
* Creates a spring between the two given nodes with the given strength. If the two nodes not
* directly connected by an edge already have a spring between them, it will be replaced by this
* one.
*
* @param node1 First of the two nodes to have a spring between them.
* @param node2 Second of the two nodes to have a spring between them.
* @param length The length of this spring (natural rest distance at which the two nodes would
* sit).
* @param strength The strength of this new spring.
* @return True if the viewer contains the two nodes and a spring between them has been created.
*/
public boolean addSpring(N node1, N node2, float length, float strength) {
Particle p1 = nodes.get(node1);
if (p1 == null) {
return false;
}
Particle p2 = nodes.get(node2);
if (p2 == null) {
return false;
}
// We may have to remove existing spring if it exists between these two nodes.
for (int i = 0; i < physics.getNumSprings(); i++) {
Spring spring = physics.getSpring(i);
if ((((spring.getOneEnd() == p1) && (spring.getTheOtherEnd() == p2))
|| ((spring.getOneEnd() == p2) && (spring.getTheOtherEnd() == p1)))
&& (spring.strength() != EDGE_STRENGTH)) {
physics.removeSpring(spring);
break;
}
}
// Add the new force.
physics.makeSpring(p1, p2, strength, DAMPING, length);
return false;
}
/**
* Adds the given edge to those to be displayed in the viewer. Note that the edge must connect
* nodes that have already been added to the viewer. This version will use the locations of the
* two nodes to calculate their distance of separation.
*
* @param edge Edge to add to the display.
* @return True if edge was added successfully. False if edge contains nodes that have not been
* added to the viewer.
*/
public boolean addEdge(E edge) {
Particle p1 = nodes.get(edge.getNode1());
if (p1 == null) {
System.err.println("Warning: Node1 not found when creating edge.");
return false;
}
Particle p2 = nodes.get(edge.getNode2());
if (p2 == null) {
System.err.println("Warning: Node2 not found when creating edge.");
return false;
}
// Only add edge if it does not already exist in the collection
if (!edges.containsKey(edge)) {
float x1 = p1.position().x();
float y1 = p1.position().y();
float x2 = p2.position().x();
float y2 = p2.position().y();
// Strength, damping, reset length
edges.put(
edge,
physics.makeSpring(
p1,
p2,
EDGE_STRENGTH,
DAMPING,
(float) Math.sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2))));
}
return true;
}
/**
* Creates a attractive or repulsive force between the two given nodes. If the two nodes already
* have a force between them, it will be replaced by this one.
*
* @param node1 First of the two nodes to have a force between them.
* @param node2 Second of the two nodes to have a force between them.
* @param force Force to create between the two nodes. If positive, the nodes will attract each
* other, if negative they will repulse. The larger the magnitude the stronger the force.
* @param minDistance Minimum distance within which no force is applied.
* @return True if the viewer contains the two nodes and a force between them has been created.
*/
public boolean addForce(N node1, N node2, float force, float minDistance) {
Particle p1 = nodes.get(node1);
if (p1 == null) {
return false;
}
Particle p2 = nodes.get(node2);
if (p2 == null) {
return false;
}
// We may have to remove existing force if it exists between these two nodes.
for (int i = 0; i < physics.getNumAttractions(); i++) {
Attraction a = physics.getAttraction(i);
if (((a.getOneEnd() == p1) && (a.getTheOtherEnd() == p2))
|| ((a.getOneEnd() == p2) && (a.getTheOtherEnd() == p1))) {
physics.removeAttraction(a);
break;
}
}
// Add the new force.
physics.makeAttraction(p1, p2, force, minDistance);
return false;
}
/** Centres the particle view on the currently visible nodes. */
private void updateCentroid() {
float xMax = Float.NEGATIVE_INFINITY,
xMin = Float.POSITIVE_INFINITY,
yMin = Float.POSITIVE_INFINITY,
yMax = Float.NEGATIVE_INFINITY;
for (int i = 0; i < physics.getNumParticles(); ++i) {
Particle p = physics.getParticle(i);
xMax = Math.max(xMax, p.position().x());
xMin = Math.min(xMin, p.position().x());
yMin = Math.min(yMin, p.position().y());
yMax = Math.max(yMax, p.position().y());
}
float xRange = xMax - xMin;
float yRange = yMax - yMin;
if ((xRange == 0) && (yRange == 0)) {
xRange = Math.max(1, xMax);
yRange = Math.max(1, yMax);
}
float zScale = (float) Math.min(height / (yRange * 1.2), width / (xRange * 1.2));
centroid.setTarget(xMin + 0.5f * xRange, yMin + 0.5f * yRange, zScale);
}
/**
* Tethers the given node to its location with the given strength.
*
* @param node The node to be tethered.
* @param strength Strength of the tether.
* @return True if the viewer contains the given node and it was tethered successfully.
*/
public boolean tether(N node, float strength) {
Particle p1 = nodes.get(node);
if (p1 == null) {
return false;
}
// Grab the tethering stake if it has already been created, otherwise create a new one.
Particle stake = stakes.get(node);
if (stake == null) {
stake = physics.makeParticle(1, node.getLocation().x, node.getLocation().y, 0);
stake.makeFixed();
stakes.put(node, stake);
}
// Grab the tether if it has already been created, otherwise create a new one.
Spring tether = tethers.get(stake);
if (tether == null) {
tether = physics.makeSpring(stake, p1, strength, DAMPING, Float.MIN_VALUE);
tethers.put(stake, tether);
} else {
tether.setStrength(strength);
}
return true;
}
/**
* Adds the given edge to those to be displayed in the viewer. Note that the edge must connect
* nodes that have already been added to the viewer. This version will fix the distance of
* separation between nodes to the given value
*
* @param edge Edge to add to the display.
* @return True if edge was added successfully. False if edge contains nodes that have not been
* added to the viewer.
*/
public boolean addEdge(E edge, float distance) {
Particle p1 = nodes.get(edge.getNode1());
if (p1 == null) {
System.err.println("Warning: Node1 not found when creating edge.");
return false;
}
Particle p2 = nodes.get(edge.getNode2());
if (p2 == null) {
System.err.println("Warning: Node2 not found when creating edge.");
return false;
}
// Only add edge if it does not already exist in the collection
if (!edges.containsKey(edge)) {
// Strength, damping, reset length
edges.put(edge, physics.makeSpring(p1, p2, EDGE_STRENGTH, DAMPING, distance));
}
return true;
}
/**
* Attempts to space out non-connected nodes from one another. This is achieved by adding a strong
* repulsive force between non-connected nodes. Note that this produces n-squared forces so can be
* slow for large networks where many nodes are not connected to each other.
*/
public void spaceNodes() {
ArrayList<Particle> pList = new ArrayList<Particle>(nodes.values());
for (int i = 0; i < pList.size(); i++) {
for (int j = 0; j < pList.size(); j++) {
if (i > j) {
Particle p1 = pList.get(i);
Particle p2 = pList.get(j);
// See if we have a connection between nodes
for (Spring spring : edges.values()) {
if (((spring.getOneEnd() == p1) && (spring.getTheOtherEnd() == p2))
|| ((spring.getOneEnd() == p2) && (spring.getTheOtherEnd() == p1))) {
// Do nothing as we already have an edge connecting these two particles
} else {
// Add a small repulsive force
physics.makeAttraction(p1, p2, -1000, 0.1f);
}
}
}
}
}
}
/**
* Adds a node to those to be displayed in the viewer.
*
* @param node Node to add to the viewer.
*/
public void addNode(N node) {
Particle p = physics.makeParticle(1, node.getLocation().x, node.getLocation().y, 0);
nodes.put(node, p);
}
/**
* Sets the drag on all particles in the system. By default drag is set to 0.75 which is enough to
* allow particles to move smoothly.
*
* @param drag Drag effect (larger numbers slow down movement).
*/
public void setDrag(float drag) {
physics.setDrag(drag);
}
/**
* Updates the positions of nodes and edges in the viewer. This method does not normally need to
* be called as update happens every time draw() is called. Calling this method can be useful if
* you wish to speed up the movement of nodes and edges by updating their position more than once
* every draw cycle.
*/
public void updateParticles() {
physics.tick(0.3f); // Advance time in the physics engine.
}