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/*
* Copyright (c) 2023 jMonkeyEngine
* All rights reserved.
*
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*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
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*
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* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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package com.jme3.scene;
import java.util.Iterator;
import java.util.LinkedList;
/**
* Iterates over the scene graph with the depth-first traversal method.
*
* This method of scene traversal allows for more control of the iteration
* process than {@link Spatial#depthFirstTraversal(com.jme3.scene.SceneGraphVisitor)}
* because it implements {@link Iterator} (enabling it to be used in for-loops).
*
* @author codex
*/
public class SceneGraphIterator implements Iterable, Iterator {
private Spatial current;
private Spatial main;
private int depth = 0;
private final LinkedList path = new LinkedList<>();
/**
* Instantiates a new {@code SceneGraphIterator} instance that
* starts iterating at the given main spatial.
*
* @param main the main spatial to start iteration from
*/
public SceneGraphIterator(Spatial main) {
if (main instanceof Node) {
path.add(new PathNode((Node)main));
depth++;
}
this.main = main;
}
@Override
public Iterator iterator() {
return this;
}
@Override
public boolean hasNext() {
if (main != null) {
return true;
}
trim();
return !path.isEmpty();
}
@Override
public Spatial next() {
if (main != null) {
current = main;
main = null;
} else {
current = path.getLast().iterator.next();
if (current instanceof Node) {
Node n = (Node)current;
if (!n.getChildren().isEmpty()) {
path.addLast(new PathNode(n));
depth++;
}
}
}
return current;
}
/**
* Gets the spatial the iterator is currently on.
*
* @return current spatial
*/
public Spatial current() {
return current;
}
/**
* Makes this iterator ignore all children of the current spatial.
* The children of the current spatial will not be iterated through.
*/
public void ignoreChildren() {
if (current instanceof Node) {
path.removeLast();
depth--;
}
}
/**
* Gets the current depth of the iterator.
*
* The depth is how far away from the main spatial the
* current spatial is. So, the main spatial's depth is 0,
* all its children's depths is 1, and all their
* children's depths is 2, etc.
*
* @return current depth, or distance from the main spatial.
*/
public int getDepth() {
// The depth field is not an accurate indicator of depth.
// Whenever the current spatial is an iterable node, the depth
// value is exactly 1 greater than it should be.
return !path.isEmpty() && current == path.getLast().node ? depth-1 : depth;
}
/**
* Trims the path to the first unexhausted node.
*/
private void trim() {
if (!path.isEmpty() && !path.getLast().iterator.hasNext()) {
path.removeLast();
depth--;
trim();
}
}
private static class PathNode {
Node node;
Iterator iterator;
PathNode(Node node) {
this.node = node;
iterator = this.node.getChildren().iterator();
}
}
}