SG_Tree.cpp

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/*
 * $Id: SG_Tree.cpp 35175 2011-02-25 13:39:04Z jesterking $
 *
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): none yet.
 *
 * ***** END GPL LICENSE BLOCK *****
 * Bounding Box
 */

#include <math.h>
 
#include "SG_BBox.h"
#include "SG_Tree.h"
#include "SG_Node.h"

SG_Tree::SG_Tree()
{
}

SG_Tree::SG_Tree(SG_Tree* left, SG_Tree* right) :
                m_left(left),
                m_right(right),
                m_client_object(NULL)
{
        if (m_left)
        {
                m_bbox = m_left->m_bbox;
                m_left->m_parent = this;
        }
        if (m_right)
        {
                m_bbox += m_right->m_bbox;
                m_right->m_parent = this;
        }
        m_center = (m_bbox.m_min + m_bbox.m_max)/2.0;
        m_radius = (m_bbox.m_max - m_bbox.m_min).length();
}
        
SG_Tree::SG_Tree(SG_Node* client) :
                m_left(NULL),
                m_right(NULL),
                m_client_object(client)
{
        m_bbox = SG_BBox(client->BBox(), client->GetWorldTransform());
        m_center = (m_bbox.m_min + m_bbox.m_max)/2.0;
        m_radius = (m_bbox.m_max - m_bbox.m_min).length();
}

SG_Tree::~SG_Tree() 
{
}
        
MT_Scalar SG_Tree::volume() const
{
        return m_bbox.volume();
}
        
void SG_Tree::dump() const
{
        if (m_left)
                m_left->dump();
        if (m_client_object)
                std::cout << m_client_object << std::endl;
        else
                std::cout << this << " ";
        if (m_right)
                m_right->dump();
}

SG_Tree* SG_Tree::Left() const
{
        return m_left;
}

SG_Tree* SG_Tree::Right() const
{
        return m_right;
}

SG_Node* SG_Tree::Client() const
{
        return m_client_object;
}

SG_Tree* SG_Tree::Find(SG_Node *node)
{
        if (m_client_object == node)
                return this;
        
        SG_Tree *left = m_left, *right = m_right;
        
        if (left && right)
        {
                if (right->m_bbox.intersects(node->BBox()))
                        std::swap(left, right);
        }
                
        if (left)
        {
                SG_Tree* ret = left->Find(node);
                if (ret) return ret;
        }
        
        if (right)
        {
                SG_Tree* ret = right->Find(node);
                if (ret) return ret;
        }
        
        return NULL;
}

void SG_Tree::get(MT_Point3 *box) const
{
        MT_Transform identity;
        identity.setIdentity();
        m_bbox.get(box, identity);
}

bool SG_Tree::inside(const MT_Point3 &point) const
{
        return m_bbox.inside(point);
}

const SG_BBox& SG_Tree::BBox() const
{
        return m_bbox;
}

void SG_Tree::SetLeft(SG_Tree *left)
{
        m_left = left;
        m_bbox += left->m_bbox;
        m_center = (m_bbox.m_min + m_bbox.m_max)/2.0;
        m_radius = (m_bbox.m_max - m_bbox.m_min).length();
}

void SG_Tree::SetRight(SG_Tree *right)
{
        m_right = right;
        m_bbox += right->m_bbox;
        m_center = (m_bbox.m_min + m_bbox.m_max)/2.0;
        m_radius = (m_bbox.m_max - m_bbox.m_min).length();
}

template<typename T>
class HalfArray
{
        std::vector<std::vector<T> > m_array;
public:
        HalfArray() {}
        ~HalfArray() {}
        
        void resize(unsigned int size)
        {
                m_array.resize(size);
                for( unsigned int i = 0; i < size; i++)
                {
                        m_array[i].resize(size - i);
                }
        }
        
        T& operator() (unsigned int x, unsigned int y)
        {
                assert(x >= y);
                return m_array[y][x - y];
        }
        
        void erase_column (unsigned int x)
        {
                for (unsigned int y = 0; y <= x; y++)
                        m_array[y].erase(m_array[y].begin() + x - y);
        }

        void delete_column (unsigned int x)
        {
                for (unsigned int y = 0; y < x; y++)
                {
                        delete m_array[y][x - y];
                        m_array[y].erase(m_array[y].begin() + x - y);
                }
        }
        
        void erase_row (unsigned int y)
        {
                m_array.erase(m_array.begin() + y);
        }
};

SG_TreeFactory::SG_TreeFactory()
{
}

SG_TreeFactory::~SG_TreeFactory()
{
}
        
void SG_TreeFactory::Add(SG_Node* client)
{
        if (client)
                m_objects.insert(new SG_Tree(client));
}

void SG_TreeFactory::Add(SG_Tree* tree)
{
        m_objects.insert(tree);
}

SG_Tree* SG_TreeFactory::MakeTreeDown(SG_BBox &bbox)
{
        if (m_objects.size() == 0)
                return NULL;
        if (m_objects.size() == 1)
                return *m_objects.begin();
                
        TreeSet::iterator it = m_objects.begin();
        SG_Tree *root = *it;
        if (m_objects.size() == 2)
        {
                root->SetRight(*(++it));
                return root;
        }
                
        if (m_objects.size() == 3)
        {
                root->SetLeft(*(++it));
                root->SetRight(*(++it));
                return root;
        }

        if (bbox.volume() < 1.0)
                return MakeTreeUp();
                
        SG_TreeFactory lefttree;
        SG_TreeFactory righttree;
        
        SG_BBox left, right;
        int hasleft = 0, hasright = 0;
        bbox.split(left, right);
        
        if (left.test(root->BBox()) == SG_BBox::INSIDE)
        {
                lefttree.Add(root);
                root = NULL;
        }
        
        if (root && right.test(root->BBox()) == SG_BBox::INSIDE)
        {
                righttree.Add(root);
                root = NULL;
        }
        
        for (++it; it != m_objects.end(); ++it)
        {
                switch (left.test((*it)->BBox()))
                {
                        case SG_BBox::INSIDE:
                                // Object is inside left tree;
                                lefttree.Add(*it);
                                hasleft++;
                                break;
                        case SG_BBox::OUTSIDE:
                                righttree.Add(*it);
                                hasright++;
                                break;
                        case SG_BBox::INTERSECT:
                                if (left.inside((*it)->Client()->GetWorldPosition()))
                                {
                                        lefttree.Add(*it);
                                        hasleft++;
                                } else {
                                        righttree.Add(*it);
                                        hasright++;
                                }
                                break;
                }
        }
        std::cout << "Left: " << hasleft << " Right: " << hasright << " Count: " << m_objects.size() << std::endl;
        
        SG_Tree *leftnode = NULL;
        if (hasleft)
                leftnode = lefttree.MakeTreeDown(left);
        
        SG_Tree *rightnode = NULL;
        if (hasright)
                rightnode = righttree.MakeTreeDown(right);
                
        if (!root)
                root = new SG_Tree(leftnode, rightnode);
        else
        {
                if (leftnode)
                        root->SetLeft(leftnode);
                if (rightnode)
                        root->SetRight(rightnode);
        }

        return root;
}

SG_Tree* SG_TreeFactory::MakeTree()
{
        if (m_objects.size() < 8)
                return MakeTreeUp();

        TreeSet::iterator it = m_objects.begin();
        SG_BBox bbox((*it)->BBox());
        for (++it; it != m_objects.end(); ++it)
                bbox += (*it)->BBox();
        
        return MakeTreeDown(bbox);
}

SG_Tree* SG_TreeFactory::MakeTreeUp()
{
        unsigned int num_objects = m_objects.size();
        
        if (num_objects < 1)
                return NULL;
        if (num_objects < 2)
                return *m_objects.begin();

        HalfArray<SG_Tree*> sizes;
        sizes.resize(num_objects);
        
        unsigned int x, y;
        TreeSet::iterator xit, yit;
        for( y = 0, yit = m_objects.begin(); y < num_objects; y++, ++yit)
        {
                sizes(y, y) = *yit;
                xit = yit;
                for( x = y+1, ++xit; x < num_objects; x++, ++xit)
                {
                        sizes(x, y) = new SG_Tree(*xit, *yit);
                        
                }
        }
        while (num_objects > 2)
        {
                /* Find the pair of bboxes that produce the smallest combined bbox. */
                unsigned int minx = UINT_MAX, miny = UINT_MAX;
                MT_Scalar min_volume = FLT_MAX;
                SG_Tree *min = NULL;
                //char temp[16];
                for( y = 0; y < num_objects; y++)
                {
                        for( x = y+1; x < num_objects; x++)
                        {
                                if (sizes(x, y)->volume() < min_volume)
                                {
                                        min = sizes(x, y);
                                        minx = x;
                                        miny = y;
                                        min_volume = sizes(x, y)->volume();
                                }
                        }
                }
                
                /* Remove other bboxes that contain the two bboxes */
                sizes.delete_column(miny);
                
                for( x = miny + 1; x < num_objects; x++)
                {
                        if (x == minx)
                                continue;
                        delete sizes(x, miny);
                }
                sizes.erase_row(miny);
                
                num_objects--;
                minx--;
                sizes(minx, minx) = min;
                for( x = minx + 1; x < num_objects; x++)
                {
                        delete sizes(x, minx);
                        sizes(x, minx) = new SG_Tree(min, sizes(x, x));
                }
                for( y = 0; y < minx; y++)
                {
                        delete sizes(minx, y);
                        sizes(minx, y) = new SG_Tree(sizes(y, y), min);
                }
        }
        return sizes(1, 0);
}