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core/StelSphericalIndex.hpp

/*
 * Stellarium
 * Copyright (C) 2009 Fabien Chereau
 *
 * 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, Suite 500, Boston, MA  02110-1335, USA.
 */

#ifndef _STELSPHERICALINDEX_HPP_
#define _STELSPHERICALINDEX_HPP_

#include "StelRegionObject.hpp"

class StelSphericalIndex
{
public:
    StelSphericalIndex(int maxObjectsPerNode = 100, int maxLevel=7);
    virtual ~StelSphericalIndex();

    void insert(StelRegionObjectP obj);

    template<class FuncObject> void processIntersectingRegions(const SphericalRegionP& region, FuncObject& func) const
    {
        rootNode->processIntersectingRegions(region, func);
    }

    template<class FuncObject> void processBoundingCapIntersectingRegions(const SphericalCap& cap, FuncObject& func) const
    {
        rootNode->processBoundingCapIntersectingRegions(cap, func);
    }
    
    template<class FuncObject> void processContainedRegions(const SphericalRegionP& region, FuncObject& func) const
    {
        rootNode->processContainedRegions(region, func);
    }

    template<class FuncObject> void processAll(FuncObject& func) const
    {
        rootNode->processAll(func);
    }

    void clear()
    {
        rootNode->clear();
    }

    unsigned int count()
    {
        CountFunc func;
        processAll<CountFunc>(func);
        return func.nb;
    }

private:
    struct CountFunc
    {
        CountFunc() : nb(0) {;}
        void operator()(const StelRegionObjectP&)
        {
            ++nb;
        }
        unsigned int nb;
    };

    struct NodeElem
    {
        NodeElem() {;}
        NodeElem(StelRegionObjectP aobj) : obj(aobj), cap(obj->getRegion()->getBoundingCap()) {;}
        StelRegionObjectP obj;
        SphericalCap cap;
    };

    struct Node
    {
        virtual ~Node() {;}
        QVector<NodeElem> elements;
        QVector<Node> children;
        SphericalConvexPolygon triangle;
        virtual void split()
        {
            // Default implementation for HTM triangle more than level 0
            Q_ASSERT(children.empty());
            Q_ASSERT(triangle.getConvexContour().size() == 3);

            const Vec3d& c0 = triangle.getConvexContour().at(0);
            const Vec3d& c1 = triangle.getConvexContour().at(1);
            const Vec3d& c2 = triangle.getConvexContour().at(2);

            Q_ASSERT((c1^c0)*c2 >= 0.0);
            Vec3d e0(c1[0]+c2[0], c1[1]+c2[1], c1[2]+c2[2]);
            e0.normalize();
            Vec3d e1(c2[0]+c0[0], c2[1]+c0[1], c2[2]+c0[2]);
            e1.normalize();
            Vec3d e2(c0[0]+c1[0], c0[1]+c1[1], c0[2]+c1[2]);
            e2.normalize();

            children.resize(4);
            children[0].triangle = SphericalConvexPolygon(e1,c0,e2);
            Q_ASSERT(children[0].triangle.checkValid());
            children[1].triangle = SphericalConvexPolygon(e0,e2,c1);
            Q_ASSERT(children[1].triangle.checkValid());
            children[2].triangle = SphericalConvexPolygon(c2,e1,e0);
            Q_ASSERT(children[2].triangle.checkValid());
            children[3].triangle = SphericalConvexPolygon(e2,e0,e1);
            Q_ASSERT(children[3].triangle.checkValid());
        }

        void clear()
        {
            elements.clear();
            children.clear();
        }
    };

    class RootNode : public Node
    {
        public:
            RootNode(int amaxObjectsPerNode, int amaxLevel) : maxObjectsPerNode(amaxObjectsPerNode), maxLevel(amaxLevel)
            {
            }

            virtual void split()
            {
                static const Vec3d vertice[6] =
                {
                    Vec3d(0,0,1), Vec3d(1,0,0), Vec3d(0,1,0), Vec3d(-1,0,0), Vec3d(0,-1,0), Vec3d(0,0,-1)
                };

                static const int verticeIndice[8][3] =
                {
                    {0,2,1}, {0,1,4}, {0,4,3}, {0,3,2}, {5,1,2}, {5,4,1}, {5,3,4}, {5,2,3}
                };

                // Create the 8 base triangles
                Node node;
                for (int i=0;i<8;++i)
                {
                    node.triangle = SphericalConvexPolygon(vertice[verticeIndice[i][0]], vertice[verticeIndice[i][1]], vertice[verticeIndice[i][2]]);
                    Q_ASSERT(node.triangle.checkValid());
                    children.append(node);
                }
            }

            void insert(const NodeElem& el, int level)
            {
                insert(*this, el, level);
            }

            template<class FuncObject> void processIntersectingRegions(const SphericalRegionP& region, FuncObject& func) const
            {
                processIntersectingRegions(*this, region, func);
            }
            
            template<class FuncObject> void processBoundingCapIntersectingRegions(const SphericalCap& cap, FuncObject& func) const
            {
                processBoundingCapIntersectingRegions(*this, cap, func);
            }

            template<class FuncObject> void processContainedRegions(const SphericalRegionP& region, FuncObject& func) const
            {
                processContainedRegions(*this, region, func);
            }

            template<class FuncObject> void processAll(FuncObject& func) const
            {
                processAll(*this, func);
            }

        private:
            void insert(Node& node, const NodeElem& el, int level)
            {
                if (node.children.isEmpty())
                {
                    node.elements.append(el);
                    // If we have too many objects in the node, we split it.
                    if (level<maxLevel && node.elements.size() > maxObjectsPerNode)
                    {
                        node.split();
                        const QVector<NodeElem> nodeElems = node.elements;
                        node.elements.clear();
                        // Re-insert the elements
                        for (QVector<NodeElem>::ConstIterator iter = nodeElems.constBegin();iter != nodeElems.constEnd(); ++iter)
                        {
                            insert(node, *iter, level);
                        }
                    }
                    return;
                }

                // If we have children and one of them contains the element, store it in a sub-level
                for (QVector<Node>::iterator iter = node.children.begin(); iter!=node.children.end(); ++iter)
                {
                    if (((SphericalRegion*)&(iter->triangle))->contains(el.obj->getRegion().data()))
                    {
                        insert(*iter, el, level+1);
                        return;
                    }
                }
                // Else store it here
                node.elements.append(el);
            }

            template<class FuncObject> void processIntersectingRegions(const Node& node, const SphericalRegionP& region, FuncObject& func) const
            {
                foreach (const NodeElem& el, node.elements)
                {
                    if (region->intersects(el.obj->getRegion().data()))
                        func(el.obj);
                }
                foreach (const Node& child, node.children)
                {
                    if (region->contains(child.triangle))
                        processAll(child, func);
                    else if (region->intersects(child.triangle))
                        processIntersectingRegions(child, region, func);
                }
            }
            
            template<class FuncObject> void processBoundingCapIntersectingRegions(const Node& node, const SphericalCap& cap, FuncObject& func) const
            {
                foreach (const NodeElem& el, node.elements)
                {
                    if (cap.intersects(el.cap))
                        func(el.obj);
                }
                foreach (const Node& child, node.children)
                {
                    if (cap.contains(child.triangle))
                        processAll(child, func);
                    else if (cap.intersects(child.triangle))
                        processBoundingCapIntersectingRegions(child, cap, func);
                }
            }

            template<class FuncObject> void processContainedRegions(const Node& node, const SphericalRegionP& region, FuncObject& func) const
            {
                foreach (const NodeElem& el, node.elements)
                {
                    if (region->contains(el.obj->getRegion().data()))
                        func(el.obj);
                }
                foreach (const Node& child, node.children)
                {
                    if (region->contains(child.triangle))
                        processAll(child, func);
                    else if (region->intersects(child.triangle))
                        processContainedRegions(child, region, func);
                }
            }

            template<class FuncObject> void processAll(const Node& node, FuncObject& func) const
            {
                foreach (const NodeElem& el, node.elements)
                    func(el.obj);
                foreach (const Node& child, node.children)
                    processAll(child, func);
            }

            int maxObjectsPerNode;
            int maxLevel;
    };

    int maxObjectsPerNode;

    RootNode* rootNode;
};

#endif // _STELSPHERICALINDEX_HPP_

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