OpenSceneGraph/src/osgUtil/TriStrip_tri_stripper.h

// tri_stripper.h: interface for the tri_stripper class.
//
//////////////////////////////////////////////////////////////////////
//
//  Copyright (C) 2002 Tanguy Fautr<74>.
//
//  This software is provided 'as-is', without any express or implied
//  warranty.  In no event will the authors be held liable for any damages
//  arising from the use of this software.
//
//  Permission is granted to anyone to use this software for any purpose,
//  including commercial applications, and to alter it and redistribute it
//  freely, subject to the following restrictions:
//
//  1. The origin of this software must not be misrepresented; you must not
//     claim that you wrote the original software. If you use this software
//     in a product, an acknowledgment in the product documentation would be
//     appreciated but is not required.eap_array.h TriStrip_tri_stripper.cpp  TriStrip_tri_stripper.h

//  2. Altered source versions must be plainly marked as such, and must not be
//     misrepresented as being the original software.
//  3. This notice may not be removed or altered from any source distribution.
//
//  Tanguy Fautr<74>
//  softdev@pandora.be
//
//////////////////////////////////////////////////////////////////////
//
//                            Tri Stripper
//                            ************
//
// Current version: 1.00 BETA 5 (10/12/2002)
//
// Comment: Triangle stripper in O(n.log(n)).
//          
//          Currently there are no protection against crazy values
//          given via SetMinStripSize() and SetCacheSize().
//          So be careful. (Min. strip size should be equal or greater
//          than 2, cache size should be about 10 for GeForce 256/2
//          and about 16-18 for GeForce 3/4.) 
//          
// History: - 1.00 BETA 5 (10/12/2002) - Fixed a bug in Stripify() that could sometimes
//                                       cause it to go into an infinite loop.
//                                       (thanks to Remy for the bug report)
//          - 1.00 BETA 4 (18/11/2002) - Removed the dependency on OpenGL:
//                                       modified gl_primitives to primitives,
//                                       and gl_primitives_vector to primitives_vector;
//                                       and added primitive_type.
//                                       (thanks to Patrik for noticing this useless dependency)
//          - 1.00 BETA 3 (18/11/2002) - Fixed a bug in LinkNeightboursTri() that could cause a crash
//                                       (thanks to Nicolas for finding it)
//          - 1.00 BETA 2 (16/11/2002) - Improved portability
//          - 1.00 BETA 1 (27/10/2002) - First public release
//
//////////////////////////////////////////////////////////////////////

#ifndef TRISTRIP_TRI_STRIPPER_H
#define TRISTRIP_TRI_STRIPPER_H

// include this to supress daft VisualStudio warnings.
#include <osg/Export>

#include <algorithm>
#include <deque>
#include <list>
#include <map>
#include <string>

#include <vector>

// namespace triangle_stripper
namespace triangle_stripper {



#include "TriStrip_graph_array.h"
#include "TriStrip_heap_array.h"

typedef unsigned int indice;

class triangle
{
public:
    triangle();
    triangle(const indice A, const indice B, const indice C);

    void SetStripID(const size_t StripID);

    indice A() const;
    indice B() const;
    indice C() const;
    size_t StripID() const;

private:
    indice m_A;
    indice m_B;
    indice m_C;
    size_t m_StripID;
};


class triangle_edge
{
public:
    triangle_edge(const indice A, const indice B, const size_t TriPos);

    indice A() const;
    indice B() const;
    size_t TriPos() const;

private:
    indice m_A;
    indice m_B;
    size_t m_TriPos;
};


class triangle_degree
{
public:
    triangle_degree();
    triangle_degree(const size_t TriPos, const size_t Degree);

    size_t Degree() const;
    size_t TriPos() const;

    void SetDegree(const size_t Degree);

private:
    size_t m_TriPos;
    size_t m_Degree;
};


class triangle_strip
{
public:
    enum start_order { ABC = 0, BCA = 1, CAB = 2 };

    triangle_strip();
    triangle_strip(size_t StartTriPos, start_order StartOrder, size_t Size);

    size_t StartTriPos() const;
    start_order StartOrder() const;
    size_t Size() const;

private:
    size_t        m_StartTriPos;
    start_order    m_StartOrder;
    size_t        m_Size;
};


struct _cmp_tri_interface_lt
{
    bool operator() (const triangle_edge & a, const triangle_edge & b) const;
};


struct _cmp_tri_degree_gt
{
    bool operator () (const triangle_degree & a, const triangle_degree & b) const;
};

class tri_stripper
{
public:

    // New Public types
    typedef std::vector<indice> indices;

    enum primitive_type {
        PT_Triangles        = 0x0004,    // = GL_TRIANGLES
        PT_Triangle_Strip    = 0x0005    // = GL_TRIANGLE_STRIP
    };

    struct primitives
    {
        indices            m_Indices;
        primitive_type    m_Type;
    };

    typedef std::vector<primitives> primitives_vector;

    struct triangles_indices_error { };


    // constructor/initializer
    inline tri_stripper(const indices & TriIndices);
    
    // Settings functions
    inline void SetCacheSize(const size_t CacheSize = 16);            // = 0 will disable the cache optimizer
    inline void SetMinStripSize(const size_t MinStripSize = 2);

    // Stripper
    void Strip(primitives_vector * out_pPrimitivesVector);    // throw triangles_indices_error();

private:

    friend struct _cmp_tri_interface_lt;





    typedef common_structures::graph_array<triangle, char> triangles_graph;
    typedef common_structures::heap_array<triangle_degree, _cmp_tri_degree_gt> triangles_heap;
    typedef std::vector<triangle_edge> triangle_edges;
    typedef std::vector<size_t> triangle_indices;
    typedef std::deque<indice> indices_cache; 


    void InitCache();
    void InitTriGraph();
    void InitTriHeap();
    void Stripify();
    void AddLeftTriangles();

    void LinkNeighboursTri(const triangle_edges & TriInterface, const triangle_edge Edge);
    void MarkTriAsTaken(const size_t i);

    triangle_edge GetLatestEdge(const triangle & Triangle, const triangle_strip::start_order Order) const;

    triangle_strip FindBestStrip();
    triangle_strip ExtendTriToStrip(const size_t StartTriPos, const triangle_strip::start_order StartOrder);
    void BuildStrip(const triangle_strip TriStrip);
    void AddIndice(const indice i);
    void AddIndiceToCache(const indice i, bool CacheHitCount = false);
    void AddTriToCache(const triangle & Tri, const triangle_strip::start_order Order);
    void AddTriToIndices(const triangle & Tri, const triangle_strip::start_order Order);

    const indices &        m_TriIndices;

    size_t                m_MinStripSize;
    size_t                m_CacheSize;

    primitives_vector    m_PrimitivesVector;
    triangles_graph        m_Triangles;
    triangles_heap        m_TriHeap;
    triangle_indices    m_NextCandidates;
    indices_cache        m_IndicesCache;
    size_t                m_StripID;
    size_t                m_CacheHits;
};




//////////////////////////////////////////////////////////////////////////
// tri_stripper Inline functions
//////////////////////////////////////////////////////////////////////////

inline tri_stripper::tri_stripper(const indices & TriIndices) : m_TriIndices(TriIndices) {
    SetCacheSize();
    SetMinStripSize();
}


inline void tri_stripper::SetCacheSize(const size_t CacheSize) {
    m_CacheSize = CacheSize;
}


inline void tri_stripper::SetMinStripSize(const size_t MinStripSize) {
    m_MinStripSize = MinStripSize;
}


inline triangle::triangle() { }


inline triangle::triangle(const indice A, const indice B, const indice C) : m_A(A), m_B(B), m_C(C), m_StripID(0) { }


inline void triangle::SetStripID(const size_t StripID) {
    m_StripID = StripID;
}


inline indice triangle::A() const {
    return m_A;
}


inline indice triangle::B() const {
    return m_B;
}


inline indice triangle::C() const {
    return m_C;
}


inline size_t triangle::StripID() const {
    return m_StripID;
}


inline triangle_edge::triangle_edge(const indice A, const indice B, const size_t TriPos) : m_A(A), m_B(B), m_TriPos(TriPos) { }


inline indice triangle_edge::A() const {
    return m_A;
}


inline indice triangle_edge::B() const {
    return m_B;
}


inline size_t triangle_edge::TriPos() const {
    return m_TriPos;
}


inline triangle_degree::triangle_degree() { }


inline triangle_degree::triangle_degree(const size_t TriPos, const size_t Degree) : m_TriPos(TriPos), m_Degree(Degree) { }


inline size_t triangle_degree::Degree() const {
    return m_Degree;
}


inline size_t triangle_degree::TriPos() const {
    return m_TriPos;
}


inline void triangle_degree::SetDegree(const size_t Degree) {
    m_Degree = Degree;
}


inline triangle_strip::triangle_strip() : m_StartTriPos(0), m_StartOrder(ABC), m_Size(0) { }


inline triangle_strip::triangle_strip(const size_t StartTriPos, const start_order StartOrder, const size_t Size)
    : m_StartTriPos(StartTriPos), m_StartOrder(StartOrder), m_Size(Size) { }


inline size_t triangle_strip::StartTriPos() const {
    return m_StartTriPos;
}


inline triangle_strip::start_order triangle_strip::StartOrder() const {
    return m_StartOrder;
}


inline size_t triangle_strip::Size() const {
    return m_Size;
}


inline bool _cmp_tri_interface_lt::operator() (const triangle_edge & a, const triangle_edge & b) const {
    const indice A1 = a.A();
    const indice B1 = a.B();
    const indice A2 = b.A();
    const indice B2 = b.B();

    if ((A1 < A2) || ((A1 == A2) && (B1 < B2)))
        return true;
    else
        return false;
}


inline bool _cmp_tri_degree_gt::operator () (const triangle_degree & a, const triangle_degree & b) const {
    // the triangle with a smaller degree has more priority 
    return a.Degree() > b.Degree();
}




} // namespace triangle_stripper

#endif