package org.jbox2d.particle;
import org.jbox2d.common.MathUtils;
import org.jbox2d.common.Vec2;
import org.jbox2d.pooling.normal.MutableStack;
public class VoronoiDiagram {
public static class Generator {
final Vec2 center = new Vec2();
int tag;
}
public static class VoronoiDiagramTask {
int m_x, m_y, m_i;
Generator m_generator;
public VoronoiDiagramTask() {}
public VoronoiDiagramTask(int x, int y, int i, Generator g) {
m_x = x;
m_y = y;
m_i = i;
m_generator = g;
}
public VoronoiDiagramTask set(int x, int y, int i, Generator g) {
m_x = x;
m_y = y;
m_i = i;
m_generator = g;
return this;
}
}
public static interface VoronoiDiagramCallback {
void callback(int aTag, int bTag, int cTag);
}
private Generator[] m_generatorBuffer;
private int m_generatorCount;
private int m_countX, m_countY;
// The diagram is an array of "pointers".
private Generator[] m_diagram;
public VoronoiDiagram(int generatorCapacity) {
m_generatorBuffer = new Generator[generatorCapacity];
for (int i = 0; i < generatorCapacity; i++) {
m_generatorBuffer[i] = new Generator();
}
m_generatorCount = 0;
m_countX = 0;
m_countY = 0;
m_diagram = null;
}
public void getNodes(VoronoiDiagramCallback callback) {
for (int y = 0; y < m_countY - 1; y++) {
for (int x = 0; x < m_countX - 1; x++) {
int i = x + y * m_countX;
Generator a = m_diagram[i];
Generator b = m_diagram[i + 1];
Generator c = m_diagram[i + m_countX];
Generator d = m_diagram[i + 1 + m_countX];
if (b != c) {
if (a != b && a != c) {
callback.callback(a.tag, b.tag, c.tag);
}
if (d != b && d != c) {
callback.callback(b.tag, d.tag, c.tag);
}
}
}
}
}
public void addGenerator(Vec2 center, int tag) {
Generator g = m_generatorBuffer[m_generatorCount++];
g.center.x = center.x;
g.center.y = center.y;
g.tag = tag;
}
private final Vec2 lower = new Vec2();
private final Vec2 upper = new Vec2();
private MutableStack<VoronoiDiagramTask> taskPool =
new MutableStack<VoronoiDiagram.VoronoiDiagramTask>(50) {
@Override
protected VoronoiDiagramTask newInstance() {
return new VoronoiDiagramTask();
}
@Override
protected VoronoiDiagramTask[] newArray(int size) {
return new VoronoiDiagramTask[size];
}
};
private final StackQueue<VoronoiDiagramTask> queue = new StackQueue<VoronoiDiagramTask>();
public void generate(float radius) {
assert (m_diagram == null);
float inverseRadius = 1 / radius;
lower.x = Float.MAX_VALUE;
lower.y = Float.MAX_VALUE;
upper.x = -Float.MAX_VALUE;
upper.y = -Float.MAX_VALUE;
for (int k = 0; k < m_generatorCount; k++) {
Generator g = m_generatorBuffer[k];
Vec2.minToOut(lower, g.center, lower);
Vec2.maxToOut(upper, g.center, upper);
}
m_countX = 1 + (int) (inverseRadius * (upper.x - lower.x));
m_countY = 1 + (int) (inverseRadius * (upper.y - lower.y));
m_diagram = new Generator[m_countX * m_countY];
queue.reset(new VoronoiDiagramTask[4 * m_countX * m_countX]);
for (int k = 0; k < m_generatorCount; k++) {
Generator g = m_generatorBuffer[k];
g.center.x = inverseRadius * (g.center.x - lower.x);
g.center.y = inverseRadius * (g.center.y - lower.y);
int x = MathUtils.max(0, MathUtils.min((int) g.center.x, m_countX - 1));
int y = MathUtils.max(0, MathUtils.min((int) g.center.y, m_countY - 1));
queue.push(taskPool.pop().set(x, y, x + y * m_countX, g));
}
while (!queue.empty()) {
VoronoiDiagramTask front = queue.pop();
int x = front.m_x;
int y = front.m_y;
int i = front.m_i;
Generator g = front.m_generator;
if (m_diagram[i] == null) {
m_diagram[i] = g;
if (x > 0) {
queue.push(taskPool.pop().set(x - 1, y, i - 1, g));
}
if (y > 0) {
queue.push(taskPool.pop().set(x, y - 1, i - m_countX, g));
}
if (x < m_countX - 1) {
queue.push(taskPool.pop().set(x + 1, y, i + 1, g));
}
if (y < m_countY - 1) {
queue.push(taskPool.pop().set(x, y + 1, i + m_countX, g));
}
}
taskPool.push(front);
}
int maxIteration = m_countX + m_countY;
for (int iteration = 0; iteration < maxIteration; iteration++) {
for (int y = 0; y < m_countY; y++) {
for (int x = 0; x < m_countX - 1; x++) {
int i = x + y * m_countX;
Generator a = m_diagram[i];
Generator b = m_diagram[i + 1];
if (a != b) {
queue.push(taskPool.pop().set(x, y, i, b));
queue.push(taskPool.pop().set(x + 1, y, i + 1, a));
}
}
}
for (int y = 0; y < m_countY - 1; y++) {
for (int x = 0; x < m_countX; x++) {
int i = x + y * m_countX;
Generator a = m_diagram[i];
Generator b = m_diagram[i + m_countX];
if (a != b) {
queue.push(taskPool.pop().set(x, y, i, b));
queue.push(taskPool.pop().set(x, y + 1, i + m_countX, a));
}
}
}
boolean updated = false;
while (!queue.empty()) {
VoronoiDiagramTask front = queue.pop();
int x = front.m_x;
int y = front.m_y;
int i = front.m_i;
Generator k = front.m_generator;
Generator a = m_diagram[i];
Generator b = k;
if (a != b) {
float ax = a.center.x - x;
float ay = a.center.y - y;
float bx = b.center.x - x;
float by = b.center.y - y;
float a2 = ax * ax + ay * ay;
float b2 = bx * bx + by * by;
if (a2 > b2) {
m_diagram[i] = b;
if (x > 0) {
queue.push(taskPool.pop().set(x - 1, y, i - 1, b));
}
if (y > 0) {
queue.push(taskPool.pop().set(x, y - 1, i - m_countX, b));
}
if (x < m_countX - 1) {
queue.push(taskPool.pop().set(x + 1, y, i + 1, b));
}
if (y < m_countY - 1) {
queue.push(taskPool.pop().set(x, y + 1, i + m_countX, b));
}
updated = true;
}
}
taskPool.push(front);
}
if (!updated) {
break;
}
}
}
}