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tri_stripper.h

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// tri_stripper.h: interface for the tri_stripper class.
//
//////////////////////////////////////////////////////////////////////
//
//  Copyright (C) 2002 Tanguy Fautré.
//
//  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.
//  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 Fautré
//  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 TRI_STRIPPER_H
#define TRI_STRIPPER_H

#include <vector>

#include "graph_array.h"
#include "heap_array.h"


// namespace triangle_stripper
namespace triangle_stripper {


class tri_stripper
{
public:

    // New Public types
    typedef unsigned short indice;
    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
    tri_stripper(const indices & TriIndices);
    
    // Settings functions
    void SetCacheSize(const size_t CacheSize = 16);         // = 0 will disable the cache optimizer
    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;


    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;
    };


    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 tri_stripper::triangle::triangle() { }


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


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


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


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


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


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


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


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


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


inline tri_stripper::triangle_degree::triangle_degree() { }


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


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


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


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


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


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


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


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


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

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


inline bool tri_stripper::_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

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