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/*******************************************************************************
* Copyright (c) 2011, Daniel Murphy
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * 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
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the nor the
* names of its contributors may be used to endorse or promote products
* derived from this software 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 TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL DANIEL MURPHY BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
******************************************************************************/
package org.jbox2d.collision.broadphase;
import java.util.Stack;
import org.jbox2d.callbacks.DebugDraw;
import org.jbox2d.callbacks.TreeCallback;
import org.jbox2d.callbacks.TreeRayCastCallback;
import org.jbox2d.collision.AABB;
import org.jbox2d.collision.RayCastInput;
import org.jbox2d.common.Color3f;
import org.jbox2d.common.MathUtils;
import org.jbox2d.common.Settings;
import org.jbox2d.common.Vec2;
import org.jbox2d.pooling.IOrderedStack;
import org.jbox2d.pooling.OrderedStack;
// updated to rev 100
/**
* A dynamic tree arranges data in a binary tree to accelerate
* queries such as volume queries and ray casts. Leafs are proxies
* with an AABB. In the tree we expand the proxy AABB by b2_fatAABBFactor
* so that the proxy AABB is bigger than the client object. This allows the client
* object to move by small amounts without triggering a tree update.
*
* @author daniel
*/
public class DynamicTree {
public static final int MAX_STACK_SIZE = 128;
private DynamicTreeNode m_root;
private int m_nodeCount;
private DynamicTreeNode lastLeaf;
private int m_insertionCount;
private int m_path;
private final Stack nodeStack = new Stack();
private final Vec2[] drawVecs = new Vec2[4];
private int nodeCounter = 0;
public DynamicTree() {
m_root = null;
m_nodeCount = 0;
m_insertionCount = 0;
m_path = 0;
lastLeaf = null;
for (int i = 0; i < drawVecs.length; i++) {
drawVecs[i] = new Vec2();
}
}
/**
* Create a proxy. Provide a tight fitting AABB and a userData pointer.
*
* @param argAABB
* @param userData
* @return
*/
public final DynamicTreeNode createProxy(final AABB argAABB, Object argUserData) {
DynamicTreeNode proxy = allocateNode();
// Fatten the aabb
proxy.aabb.lowerBound.x = argAABB.lowerBound.x - Settings.aabbExtension;
proxy.aabb.lowerBound.y = argAABB.lowerBound.y - Settings.aabbExtension;
proxy.aabb.upperBound.x = argAABB.upperBound.x + Settings.aabbExtension;
proxy.aabb.upperBound.y = argAABB.upperBound.y + Settings.aabbExtension;
proxy.userData = argUserData;
insertLeaf(proxy);
int iterationCount = m_nodeCount >> 4;
int tryCount = 0;
int height = computeHeight();
while (height > 64 && tryCount < 10) {
rebalance(iterationCount);
height = computeHeight();
++tryCount;
}
return proxy;
}
/**
* Destroy a proxy
*
* @param argProxy
*/
public final void destroyProxy(DynamicTreeNode argProxy) {
assert (argProxy != null);
assert (argProxy.isLeaf());
removeLeaf(argProxy);
freeNode(argProxy);
}
// djm pooling
private final Vec2 d = new Vec2();
/**
* Move a proxy with a swepted AABB. If the proxy has moved outside of its fattened
* AABB,
* then the proxy is removed from the tree and re-inserted. Otherwise
* the function returns immediately.
*
* @return true if the proxy was re-inserted.
*/
public final boolean moveProxy(DynamicTreeNode argProxy, final AABB argAABB, Vec2 displacement) {
assert (argProxy != null);
assert (argProxy.isLeaf());
if (argProxy.aabb.contains(argAABB)) {
return false;
}
removeLeaf(argProxy);
// Extend AABB
argAABB.lowerBound.x -= Settings.aabbExtension;
argAABB.lowerBound.y -= Settings.aabbExtension;
argAABB.upperBound.x += Settings.aabbExtension;
argAABB.upperBound.y += Settings.aabbExtension;
// Predict AABB displacement.
d.set(displacement).mulLocal(Settings.aabbMultiplier);
if (d.x < 0.0f) {
argAABB.lowerBound.x += d.x;
}
else {
argAABB.upperBound.x += d.x;
}
if (d.y < 0.0f) {
argAABB.lowerBound.y += d.y;
}
else {
argAABB.upperBound.y += d.y;
}
argProxy.aabb.set(argAABB);
insertLeaf(argProxy);
return true;
}
/**
* Rebalances the tree for the given iterations. Goes through
* the tree by child1-child2 order (then back to root). If given enough
* iterations it will hit all the nodes. It starts off at the last leaf
* that it reinserted.
*
* @param argIterations
*/
public final void rebalance(int argIterations) {
if (m_root == null) {
return;
}
DynamicTreeNode currNode;
for (int i = 0; i < argIterations; i++) {
currNode = m_root;
int bit = 0;
while (currNode.isLeaf() == false) {
int goLeft = (m_path >> bit) & 1;
if (goLeft == 0) {
currNode = currNode.child1;
}
else {
currNode = currNode.child2;
}
bit = (bit + 1) & 31;
}
++m_path;
removeLeaf(currNode);
insertLeaf(currNode);
}
}
/**
* Query an AABB for overlapping proxies. The callback class
* is called for each proxy that overlaps the supplied AABB.
*
* @param argCallback
* @param argAABB
*/
public final void query(TreeCallback argCallback, AABB argAABB) {
query(argCallback, argAABB, m_root, 1);
}
// recursive query
// returns if to proceed
private final boolean query(TreeCallback argCallback, AABB argAABB, DynamicTreeNode argNode, int count) {
if (argNode == null) {
return true;
}
if (AABB.testOverlap(argAABB, argNode.aabb)) {
if (argNode.isLeaf()) {
boolean proceed = argCallback.treeCallback(argNode);
if (!proceed) {
return false;
}
}
else {
if (count < MAX_STACK_SIZE) {
boolean proceed = query(argCallback, argAABB, argNode.child1, ++count);
if (!proceed) {
return false;
}
}
if (count < MAX_STACK_SIZE) {
boolean proceed = query(argCallback, argAABB, argNode.child2, ++count);
if (!proceed) {
return false;
}
}
}
}
return true;
}
// stacks because it's recursive
private final IOrderedStack vec2s = new OrderedStack(Vec2.class, MAX_STACK_SIZE * 3 + 4, 10);
private final AABB aabb = new AABB();
private final RayCastInput subInput = new RayCastInput();
/**
* Ray-cast against the proxies in the tree. This relies on the callback
* to perform a exact ray-cast in the case were the proxy contains a shape.
* The callback also performs the any collision filtering. This has performance
* roughly equal to k * log(n), where k is the number of collisions and n is the
* number of proxies in the tree.
*
* @param argInput
* the ray-cast input data. The ray extends from p1 to p1 + maxFraction *
* (p2 - p1).
* @param argCallback
* a callback class that is called for each proxy that is hit by the ray.
*/
public void raycast(TreeRayCastCallback argCallback, RayCastInput argInput) {
final Vec2 r = vec2s.pop();
final Vec2 v = vec2s.pop();
final Vec2 absV = vec2s.pop();
Vec2 p1 = argInput.p1;
Vec2 p2 = argInput.p2;
r.set(p2).subLocal(p1);
assert (r.lengthSquared() > 0f);
r.normalize();
// v is perpendicular to the segment.
Vec2.crossToOut(1f, r, v);
absV.set(v).absLocal();
// Separating axis for segment (Gino, p80).
// |dot(v, p1 - c)| > dot(|v|, h)
float[] maxFraction = new float[1];
maxFraction[0] = argInput.maxFraction;
// Build a bounding box for the segment.
final AABB segAABB = aabb;
// b2Vec2 t = p1 + maxFraction * (p2 - p1);
final Vec2 temp = vec2s.pop();
temp.set(p2).subLocal(p1).mulLocal(maxFraction[0]).addLocal(p1);
Vec2.minToOut(p1, temp, segAABB.lowerBound);
Vec2.maxToOut(p1, temp, segAABB.upperBound);
raycast(m_root, argInput, 0, segAABB, v, p1, p2, absV, maxFraction, argCallback);
vec2s.push(4);
}
public boolean raycast(DynamicTreeNode argNode, RayCastInput argInput, int argCount, AABB argSegAABB, Vec2 argV,
Vec2 argP1, Vec2 argP2, Vec2 argAbs_v, float[] argMaxFraction, TreeRayCastCallback argCallback) {
// start part from c++ code that's in the while loop
if (argNode == null) {
return false;
}
if (AABB.testOverlap(argNode.aabb, argSegAABB) == false) {
return false;
}
final Vec2 temp = vec2s.pop();
final Vec2 c = vec2s.pop();
final Vec2 h = vec2s.pop();
argNode.aabb.getCenterToOut(c);
argNode.aabb.getExtentsToOut(h);
temp.set(argP1).subLocal(c);
float separation = MathUtils.abs(Vec2.dot(argV, temp)) - Vec2.dot(argAbs_v, h);
if (separation > 0f) {
vec2s.push(3);
return false;
}
if (argNode.isLeaf()) {
subInput.p1.set(argInput.p1);
subInput.p2.set(argInput.p2);
subInput.maxFraction = argMaxFraction[0];
float value = argCallback.raycastCallback(subInput, argNode);
if (value == 0f) {
vec2s.push(3);
// The client has terminated the ray cast.
return true;
}
if (value > 0f) {
// Update segment bounding box
argMaxFraction[0] = value;
temp.set(argP2).subLocal(argP1).mulLocal(value).addLocal(argP1);
Vec2.minToOut(argP1, temp, argSegAABB.lowerBound);
Vec2.maxToOut(argP1, temp, argSegAABB.upperBound);
}
}
else {
if (argCount < MAX_STACK_SIZE) {
if (raycast(argNode.child1, argInput, ++argCount, argSegAABB, argV, argP1, argP2, argAbs_v,
argMaxFraction, argCallback)) {
vec2s.push(3);
return true; // to stop whole raycast
}
}
if (argCount < MAX_STACK_SIZE) {
if (raycast(argNode.child2, argInput, ++argCount, argSegAABB, argV, argP1, argP2, argAbs_v,
argMaxFraction, argCallback)) {
vec2s.push(3);
return true; // to stop whole raycast
}
}
}
vec2s.push(3);
return false;
}
/**
* Compute the height of the tree.
*/
public final int computeHeight() {
return computeHeight(m_root);
}
private final int computeHeight(DynamicTreeNode argNode) {
if (argNode == null) {
return 0;
}
assert (argNode != null);
int height1 = computeHeight(argNode.child1);
int height2 = computeHeight(argNode.child2);
return 1 + MathUtils.max(height1, height2);
}
private final DynamicTreeNode allocateNode() {
if (nodeStack.isEmpty()) {
nodeStack.push(new DynamicTreeNode());
nodeStack.push(new DynamicTreeNode());
nodeStack.push(new DynamicTreeNode());
nodeStack.push(new DynamicTreeNode());
nodeStack.push(new DynamicTreeNode());
nodeStack.push(new DynamicTreeNode());
}
DynamicTreeNode node = nodeStack.pop();
node.parent = null;
node.child1 = null;
node.child2 = null;
node.userData = null;
node.key = nodeCounter++;
m_nodeCount++;
return node;
}
/**
* returns a node to the pool
*
* @param argNode
*/
private final void freeNode(DynamicTreeNode argNode) {
assert (argNode != null);
assert (0 < m_nodeCount);
nodeStack.push(argNode);
m_nodeCount--;
}
private final Vec2 center = new Vec2();
private final Vec2 delta1 = new Vec2();
private final Vec2 delta2 = new Vec2();
private final void insertLeaf(DynamicTreeNode argNode) {
m_insertionCount++;
if (m_root == null) {
m_root = argNode;
argNode.parent = null;
return;
}
// find the best sibling
argNode.aabb.getCenterToOut(center);
DynamicTreeNode sibling = m_root;
DynamicTreeNode child1, child2;
if (sibling.isLeaf() == false) {
do {
child1 = sibling.child1;
child2 = sibling.child2;
child1.aabb.getCenterToOut(delta1);
child2.aabb.getCenterToOut(delta2);
delta1.subLocal(center).absLocal();
delta2.subLocal(center).absLocal();
float norm1 = delta1.x + delta1.y;
float norm2 = delta2.x + delta2.y;
if (norm1 < norm2) {
sibling = child1;
}
else {
sibling = child2;
}
}
while (sibling.isLeaf() == false);
}
// Create a parent for the siblings
DynamicTreeNode node1 = sibling.parent;
DynamicTreeNode node2 = allocateNode();
node2.parent = node1;
node2.userData = null;
node2.aabb.combine(argNode.aabb, sibling.aabb);
// was that the head node?
if (node1 != null) {
if (sibling.parent.child1 == sibling) {
node1.child1 = node2;
}
else {
node1.child2 = node2;
}
node2.child1 = sibling;
node2.child2 = argNode;
sibling.parent = node2;
argNode.parent = node2;
// build the aabb's up in case we expanded them out
do {
if (node1.aabb.contains(node2.aabb)) {
break;
}
node1.aabb.combine(node1.child1.aabb, node1.child2.aabb);
node2 = node1;
node1 = node1.parent;
}
while (node1 != null);
}
else {
node2.child1 = sibling;
node2.child2 = argNode;
sibling.parent = node2;
argNode.parent = node2;
m_root = node2;
}
}
private final AABB oldAABB = new AABB();
private final void removeLeaf(DynamicTreeNode argNode) {
if (argNode == m_root) {
m_root = null;
if (lastLeaf == argNode) {
lastLeaf = null;
}
return;
}
DynamicTreeNode node2 = argNode.parent;
DynamicTreeNode node1 = node2.parent;
DynamicTreeNode sibling;
if (node2.child1 == argNode) {
sibling = node2.child2;
}
else {
sibling = node2.child1;
}
if (node1 != null) {
// Destroy node2 and connect node1 to sibling.
if (node1.child1 == node2) {
node1.child1 = sibling;
}
else {
node1.child2 = sibling;
}
sibling.parent = node1;
freeNode(node2);
// Adjust ancestor bounds. if the old one was larger, we just keep it
while (node1 != null) {
oldAABB.set(node1.aabb);
node1.aabb.combine(node1.child1.aabb, node1.child2.aabb);
if (oldAABB.contains(node1.aabb)) {
break;
}
node1 = node1.parent;
}
}
else {
m_root = sibling;
sibling.parent = null;
freeNode(node2);
}
// in case we just removed our last leaf
// (this is for rebalancing)
if (lastLeaf == argNode) {
lastLeaf = m_root;
}
}
public void drawTree(DebugDraw argDraw) {
if (m_root == null) {
return;
}
int height = computeHeight();
drawTree(argDraw, m_root, 0, height);
}
private final Color3f color = new Color3f();
private final Vec2 textVec = new Vec2();
public void drawTree(DebugDraw argDraw, DynamicTreeNode argNode, int spot, int height) {
argNode.aabb.getVertices(drawVecs);
color.set(1, (height - spot) * 1f / height, (height - spot) * 1f / height);
argDraw.drawPolygon(drawVecs, 4, color);
argDraw.getViewportTranform().getWorldToScreen(argNode.aabb.upperBound, textVec);
argDraw.drawString(textVec.x, textVec.y, (spot + 1) + "/" + height, color);
if (argNode.child1 != null) {
drawTree(argDraw, argNode.child1, spot + 1, height);
}
if (argNode.child2 != null) {
drawTree(argDraw, argNode.child2, spot + 1, height);
}
}
}
