SG_Tree.cpp

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/*
 * ***** 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);
}