OpenSceneGraph/include/osgUtil/IntersectionVisitor

/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield 
 *
 * This library is open source and may be redistributed and/or modified under  
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 * 
 * This library 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 
 * OpenSceneGraph Public License for more details.
*/

#ifndef OSGUTIL_INTERSECTIONVISITOR
#define OSGUTIL_INTERSECTIONVISITOR 1

#include <osg/NodeVisitor>
#include <osgUtil/Export>

#include <list>

namespace osgUtil
{

// forward declare to allow Intersector to reference it.
class IntersectionVisitor;

/** Pure virtual base class for implementating custom intersection technique.
  * To implement a specific intersection technique on must override all
  * the pure virtue methods, concrete examples of how to do this can be seen in
  * the LineSegmentIntersector. */
class Intersector : public osg::Referenced
{
    public:
    
        virtual Intersector* clone(osgUtil::IntersectionVisitor& iv) = 0;
        
        virtual void merge(Intersector* intersector) = 0;

        virtual bool enter(const osg::Node& node) = 0;
        
        virtual void leave() = 0;
        
        virtual void intersect(osgUtil::IntersectionVisitor& iv, osg::Drawable* drawable) = 0;
        
        virtual void reset() = 0;
        
        virtual bool containsIntersections() = 0;

};

/** Concrent class for implementing line intersections with the scene graph.
  * To be used in conjunction with IntersectionVisitor. */
class LineSegmentIntersector : public Intersector
{
    public:
    
        LineSegmentIntersector(const osg::Vec3d& start, const osg::Vec3d& end);
    
        struct Intersection
        {
            bool operator < (const Intersection& rhs) const { return ratio < rhs.ratio; }

            typedef std::vector<unsigned int> IndexList;

            double                          ratio;
            osg::NodePath                   nodePath;
            osg::ref_ptr<osg::Drawable>     drawable;
            osg::ref_ptr<osg::RefMatrix>    matrix;
            osg::Vec3d                      localIntersectionPoint;
            osg::Vec3                       localIntersectionNormal;
            IndexList                       indexList;
            unsigned int                    primitiveIndex;
        };
        
        typedef std::multiset<Intersection> Intersections;
        
        Intersections& getIntersections() { return _intersections; }

    public:

        virtual Intersector* clone(osgUtil::IntersectionVisitor& iv);
        
        virtual void merge(Intersector* intersector);

        virtual bool enter(const osg::Node& node);
        
        virtual void leave();
        
        virtual void intersect(osgUtil::IntersectionVisitor& iv, osg::Drawable* drawable);
        
        virtual void reset();

        virtual bool containsIntersections() { return !_intersections.empty(); }

    protected:
    
        bool intersects(const osg::BoundingSphere& bs);
        bool intersectAndClip(osg::Vec3d& s, osg::Vec3d& e,const osg::BoundingBox& bb);

        osg::Vec3d  _start;
        osg::Vec3d  _end;
        
        Intersections _intersections;
    
};

/** InteresectionVisitor is used to testing for intersections with the scene, traversing the scene using generic osgUtil::Intersector's to test against the scene.
  * To implement different types of intersection techniques, one implements custom versions of the osgUtil::Intersector, and then
  * pass the constructed intersector to the IntersectionVisitor.*/
class OSGUTIL_EXPORT IntersectionVisitor : public osg::NodeVisitor
{
    public:

        /** Callback used to implement the reading of external files, allowing support for paged databases to be
          * intergrated with IntersectionVisitor.  A concrete implementation can be found in osgDB.
          * Note, this loose coupling approach is required as osgUtil is independent from osgDB where the file reading
          * is implemented, and osgDB itself is dependent upon osgUtil so a circular dependency would result from
          * tighter integration.*/
        struct ReadCallback : public osg::Referenced
        {
            virtual osg::Node* readNodeFile(const std::string& filename) = 0;
        };


        IntersectionVisitor(Intersector* intersector=0, ReadCallback* readCallback=0);
        
        virtual void reset();

        /** Set the intersector that will be used to intersect with the scene, and to store any hits that occur.*/
        void setIntersector(Intersector* intersector);
        
        /** Get the intersector that will be used to intersect with the scene, and to store any hits that occur.*/
        Intersector* getIntersector() { return _intersectorStack.empty() ? 0 : _intersectorStack.front().get(); }

        /** Get the const intersector that will be used to intersect with the scene, and to store any hits that occur.*/
        const Intersector* getIntersector() const { return _intersectorStack.empty() ? 0 : _intersectorStack.front().get(); }


        /** Set the read callback.*/
        void setReadCallback(ReadCallback* rc) { _readCallback = rc; }

        /** Get the read callback.*/
        ReadCallback* getReadCallback() { return _readCallback.get(); }

        /** Get the const read callback.*/
        const ReadCallback* getReadCallback() const { return _readCallback.get(); }

        osg::RefMatrix* getWindowMatrix() { return _windowStack.empty() ? 0 :  _windowStack.back().get(); }
        osg::RefMatrix* getProjectionMatrix() { return _projectionStack.empty() ? 0 :  _projectionStack.back().get(); }
        osg::RefMatrix* getViewMatrix() { return _viewStack.empty() ? 0 :  _viewStack.back().get(); }
        osg::RefMatrix* getModelMatrix() { return _modelStack.empty() ? 0 :  _modelStack.back().get(); }


    public:

        virtual void apply(osg::Node& node);
        virtual void apply(osg::Geode& geode);
        virtual void apply(osg::Billboard& geode);
        virtual void apply(osg::Group& group);
        virtual void apply(osg::LOD& lod);
        virtual void apply(osg::PagedLOD& lod);
        virtual void apply(osg::Transform& transform);
        virtual void apply(osg::Projection& projection);
        virtual void apply(osg::CameraNode& camera);
    
    protected:
    
        inline bool enter(const osg::Node& node) { return _intersectorStack.empty() ? false : _intersectorStack.back()->enter(node); }
        inline void leave() { _intersectorStack.back()->leave(); }
        inline void intersect(osg::Drawable* drawable) { _intersectorStack.back()->intersect(*this, drawable); }
        inline void push_clone() { _intersectorStack.push_back ( _intersectorStack.front()->clone(*this) ); }
        inline void pop_clone() { if (_intersectorStack.size()>=2) { _intersectorStack.front()->merge(_intersectorStack.back().get()); _intersectorStack.pop_back(); } }

        typedef std::list< osg::ref_ptr<Intersector> > IntersectorStack;
        IntersectorStack _intersectorStack;
        
        osg::ref_ptr<ReadCallback> _readCallback;
        
        typedef std::list< osg::ref_ptr<osg::RefMatrix> > MatrixStack;
        MatrixStack _windowStack;
        MatrixStack _projectionStack;
        MatrixStack _viewStack;
        MatrixStack _modelStack;

};

}

#endif