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/*
* KdTree.cpp
* RVO2-3D Library
*
* Copyright 2008 University of North Carolina at Chapel Hill
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Please send all bug reports to <geom@cs.unc.edu>.
*
* The authors may be contacted via:
*
* Jur van den Berg, Stephen J. Guy, Jamie Snape, Ming C. Lin, Dinesh Manocha
* Dept. of Computer Science
* 201 S. Columbia St.
* Frederick P. Brooks, Jr. Computer Science Bldg.
* Chapel Hill, N.C. 27599-3175
* United States of America
*
* <http://gamma.cs.unc.edu/RVO2/>
*/
#include "KdTree.h"
#include <algorithm>
#include "Agent.h"
#include "Definitions.h"
namespace RVO {
const size_t RVO_MAX_LEAF_SIZE = 10;
KdTree::KdTree() { }
void KdTree::buildAgentTree(std::vector<Agent *> agents)
{
agents_.swap(agents);
if (!agents_.empty()) {
agentTree_.resize(2 * agents_.size() - 1);
buildAgentTreeRecursive(0, agents_.size(), 0);
}
}
void KdTree::buildAgentTreeRecursive(size_t begin, size_t end, size_t node)
{
agentTree_[node].begin = begin;
agentTree_[node].end = end;
agentTree_[node].minCoord = agents_[begin]->position_;
agentTree_[node].maxCoord = agents_[begin]->position_;
for (size_t i = begin + 1; i < end; ++i) {
agentTree_[node].maxCoord[0] = std::max(agentTree_[node].maxCoord[0], agents_[i]->position_.x());
agentTree_[node].minCoord[0] = std::min(agentTree_[node].minCoord[0], agents_[i]->position_.x());
agentTree_[node].maxCoord[1] = std::max(agentTree_[node].maxCoord[1], agents_[i]->position_.y());
agentTree_[node].minCoord[1] = std::min(agentTree_[node].minCoord[1], agents_[i]->position_.y());
agentTree_[node].maxCoord[2] = std::max(agentTree_[node].maxCoord[2], agents_[i]->position_.z());
agentTree_[node].minCoord[2] = std::min(agentTree_[node].minCoord[2], agents_[i]->position_.z());
}
if (end - begin > RVO_MAX_LEAF_SIZE) {
/* No leaf node. */
size_t coord;
if (agentTree_[node].maxCoord[0] - agentTree_[node].minCoord[0] > agentTree_[node].maxCoord[1] - agentTree_[node].minCoord[1] && agentTree_[node].maxCoord[0] - agentTree_[node].minCoord[0] > agentTree_[node].maxCoord[2] - agentTree_[node].minCoord[2]) {
coord = 0;
}
else if (agentTree_[node].maxCoord[1] - agentTree_[node].minCoord[1] > agentTree_[node].maxCoord[2] - agentTree_[node].minCoord[2]) {
coord = 1;
}
else {
coord = 2;
}
const float splitValue = 0.5f * (agentTree_[node].maxCoord[coord] + agentTree_[node].minCoord[coord]);
size_t left = begin;
size_t right = end;
while (left < right) {
while (left < right && agents_[left]->position_[coord] < splitValue) {
++left;
}
while (right > left && agents_[right - 1]->position_[coord] >= splitValue) {
--right;
}
if (left < right) {
std::swap(agents_[left], agents_[right - 1]);
++left;
--right;
}
}
size_t leftSize = left - begin;
if (leftSize == 0) {
++leftSize;
++left;
++right;
}
agentTree_[node].left = node + 1;
agentTree_[node].right = node + 2 * leftSize;
buildAgentTreeRecursive(begin, left, agentTree_[node].left);
buildAgentTreeRecursive(left, end, agentTree_[node].right);
}
}
void KdTree::computeAgentNeighbors(Agent *agent, float rangeSq) const
{
queryAgentTreeRecursive(agent, rangeSq, 0);
}
void KdTree::queryAgentTreeRecursive(Agent *agent, float &rangeSq, size_t node) const
{
if (agentTree_[node].end - agentTree_[node].begin <= RVO_MAX_LEAF_SIZE) {
for (size_t i = agentTree_[node].begin; i < agentTree_[node].end; ++i) {
agent->insertAgentNeighbor(agents_[i], rangeSq);
}
}
else {
const float distSqLeft = sqr(std::max(0.0f, agentTree_[agentTree_[node].left].minCoord[0] - agent->position_.x())) + sqr(std::max(0.0f, agent->position_.x() - agentTree_[agentTree_[node].left].maxCoord[0])) + sqr(std::max(0.0f, agentTree_[agentTree_[node].left].minCoord[1] - agent->position_.y())) + sqr(std::max(0.0f, agent->position_.y() - agentTree_[agentTree_[node].left].maxCoord[1])) + sqr(std::max(0.0f, agentTree_[agentTree_[node].left].minCoord[2] - agent->position_.z())) + sqr(std::max(0.0f, agent->position_.z() - agentTree_[agentTree_[node].left].maxCoord[2]));
const float distSqRight = sqr(std::max(0.0f, agentTree_[agentTree_[node].right].minCoord[0] - agent->position_.x())) + sqr(std::max(0.0f, agent->position_.x() - agentTree_[agentTree_[node].right].maxCoord[0])) + sqr(std::max(0.0f, agentTree_[agentTree_[node].right].minCoord[1] - agent->position_.y())) + sqr(std::max(0.0f, agent->position_.y() - agentTree_[agentTree_[node].right].maxCoord[1])) + sqr(std::max(0.0f, agentTree_[agentTree_[node].right].minCoord[2] - agent->position_.z())) + sqr(std::max(0.0f, agent->position_.z() - agentTree_[agentTree_[node].right].maxCoord[2]));
if (distSqLeft < distSqRight) {
if (distSqLeft < rangeSq) {
queryAgentTreeRecursive(agent, rangeSq, agentTree_[node].left);
if (distSqRight < rangeSq) {
queryAgentTreeRecursive(agent, rangeSq, agentTree_[node].right);
}
}
}
else {
if (distSqRight < rangeSq) {
queryAgentTreeRecursive(agent, rangeSq, agentTree_[node].right);
if (distSqLeft < rangeSq) {
queryAgentTreeRecursive(agent, rangeSq, agentTree_[node].left);
}
}
}
}
}
}
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