Hello JGO community,
I followed this tutorial when creating a QuadTree class and made a few modifications based on the feedback on the tutorial. Everything works as expected until I start clearing and inserting entities, as indicated in the tutorial, each frame. Before clearing and inserting, there are multiple quadrants and only 7 entities are marked for collision detection. However, after clearing and inserting, there is only one quadrant and all 33 entities are marked for collision detection. I would post a video, but it seems redundant as all I said is happening in the video.
Here is the QuadTree code:
public class QuadTree {
private static final int MAX_OBJECTS = 1;
private static final int MAX_LEVELS = 3;
private int level;
private Rectangle bounds;
private Array<Entity> entities;
private QuadTree[] nodes;
public QuadTree(int level, Rectangle bounds) {
this.level = level;
this.bounds = bounds;
this.entities = new Array<Entity>();
this.nodes = new QuadTree[4];
}
public void draw(ShapeRenderer shapes) {
shapes.setColor(Color.MAGENTA);
shapes.rect(bounds.x, bounds.y, bounds.width, bounds.height);
for (int i = 0; i < nodes.length; i++) {
QuadTree node = nodes[i];
if (node != null) {
node.draw(shapes);
}
}
}
public void clear() {
entities.clear();
for (int i = 0; i < nodes.length; i++) {
if (nodes[i] != null) {
nodes[i].clear();
nodes[i] = null;
}
}
}
private void split() {
final float x = bounds.x;
final float y = bounds.y;
final float w = bounds.width / 2f;
final float h = bounds.height / 2f;
final int level = this.level++;
nodes[0] = new QuadTree(level, new Rectangle(x + w, y, w, h));
nodes[1] = new QuadTree(level, new Rectangle(x, y, w, h));
nodes[2] = new QuadTree(level, new Rectangle(x, y + h, w, h));
nodes[3] = new QuadTree(level, new Rectangle(x + w, y + h, w, h));
}
private int getIndex(Rectangle r) {
int index = -1;
float verticalMidpoint = bounds.getX() + (bounds.getWidth() / 2f);
float horizontalMidpoint = bounds.getY() + (bounds.getHeight() / 2f);
boolean topQuadrant = r.getY() < horizontalMidpoint && r.getY() + r.getHeight() < horizontalMidpoint;
boolean bottomQuadrant = r.getY() > horizontalMidpoint;
if (r.getX() < verticalMidpoint && r.getX() + r.getWidth() < verticalMidpoint) {
if (topQuadrant) {
index = 1;
} else if (bottomQuadrant) {
index = 2;
}
} else if (r.getX() > verticalMidpoint) {
if (topQuadrant) {
index = 0;
} else if (bottomQuadrant) {
index = 3;
}
}
return index;
}
public void insert(Entity entity) {
if (nodes[0] != null) {
final int index = getIndex(entity.getComponent(BoundsComp.class));
if (index != -1) {
nodes[index].insert(entity);
return;
}
}
entities.add(entity);
if (entities.size > MAX_OBJECTS && level < MAX_LEVELS) {
if (nodes[0] == null) {
split();
}
int i = 0;
while (i < entities.size) {
final int index = getIndex(entity.getComponent(BoundsComp.class));
if (index != -1) {
nodes[index].insert(entities.removeIndex(i));
} else {
i++;
}
}
}
}
public void retrieve(Array<Entity> entities, Rectangle r) {
if (nodes[0] != null) {
final int index = getIndex(r);
if (index != -1) {
nodes[index].retrieve(entities, r);
} else {
for (int i = 0; i < nodes.length; i++) {
nodes[i].retrieve(entities, r);
}
}
}
entities.addAll(this.entities);
}
}
Here is the clearing and inserting code:
quadTree.clear();
ImmutableArray<Entity> entities = getEntities();
for (int i = 0; i < entities.size(); i++) {
quadTree.insert(entities.get(i));
}
I have no idea what I’m doing wrong. Thanks in advance!
