vlookup.cpp

Go to the documentation of this file.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#pragma warning(disable:4786)

#include <vector>
#include <map>
#include <set>
// CodeSnippet provided by John W. Ratcliff
// on March 23, 2006.
//
// mailto: jratcliff@infiniplex.net
//
// Personal website: http://jratcliffscarab.blogspot.com
// Coding Website:   http://codesuppository.blogspot.com
// FundRaising Blog: http://amillionpixels.blogspot.com
// Fundraising site: http://www.amillionpixels.us
// New Temple Site:  http://newtemple.blogspot.com
//
// This snippet shows how to 'hide' the complexity of
// the STL by wrapping some useful piece of functionality
// around a handful of discrete API calls.
//
// This API allows you to create an indexed triangle list
// from a collection of raw input triangles.  Internally
// it uses an STL set to build the lookup table very rapidly.
//
// Here is how you would use it to build an indexed triangle
// list from a raw list of triangles.
//
// (1) create a 'VertexLookup' interface by calling
//
//     VertexLook vl = Vl_createVertexLookup();
//
// (2) For each vertice in each triangle call:
//
//     unsigned int i1 = Vl_getIndex(vl,p1);
//     unsigned int i2 = Vl_getIndex(vl,p2);
//     unsigned int i3 = Vl_getIndex(vl,p3);
//
//     save the 3 indices into your triangle list array.
//
// (3) Get the vertex array by calling:
//
//     const double *vertices = Vl_getVertices(vl);
//
// (4) Get the number of vertices so you can copy them into
//     your own buffer.
//     unsigned int vcount = Vl_getVcount(vl);
//
// (5) Release the VertexLookup interface when you are done with it.
//     Vl_releaseVertexLookup(vl);
//
// Teaches the following lessons:
//
//    How to wrap the complexity of STL and C++ classes around a
//    simple API interface.
//
//    How to use an STL set and custom comparator operator for
//    a complex data type.
//
//    How to create a template class.
//
//    How to achieve significant performance improvements by
//    taking advantage of built in STL containers in just
//    a few lines of code.
//
//    You could easily modify this code to support other vertex
//    formats with any number of interpolants.




#include "vlookup.h"

namespace ConvexDecomposition
{

class VertexPosition
{
public:
  VertexPosition(void) { };
  VertexPosition(const double *p)
  {
        mPos[0] = p[0];
        mPos[1] = p[1];
        mPos[2] = p[2];
  };

        void Set(int index,const double *pos)
        {
                const double * p = &pos[index*3];

                mPos[0]    = p[0];
                mPos[1]    = p[1];
                mPos[2]    = p[2];

        };

  double GetX(void) const { return mPos[0]; };
  double GetY(void) const { return mPos[1]; };
  double GetZ(void) const { return mPos[2]; };

        double mPos[3];
};


template <typename Type> class VertexLess
{
public:
        typedef std::vector< Type > VertexVector;

        bool operator()(int v1,int v2) const;

        static void SetSearch(const Type& match,VertexVector *list)
        {
                mFind = match;
                mList = list;
        };

private:
        const Type& Get(int index) const
        {
                if ( index == -1 ) return mFind;
                VertexVector &vlist = *mList;
                return vlist[index];
        }
        static Type mFind; // vertice to locate.
        static VertexVector  *mList;
};

template <typename Type> class VertexPool
{
public:
        typedef std::set<int, VertexLess<Type> > VertexSet;
        typedef std::vector< Type > VertexVector;

        int GetVertex(const Type& vtx)
        {
                VertexLess<Type>::SetSearch(vtx,&mVtxs);
                typename VertexSet::iterator found;
                found = mVertSet.find( -1 );
                if ( found != mVertSet.end() )
                {
                        return *found;
                }
                int idx = (int)mVtxs.size();
                mVtxs.push_back( vtx );
                mVertSet.insert( idx );
                return idx;
        };

        const double * GetPos(int idx) const
        {
                return mVtxs[idx].mPos;
        }

        const Type& Get(int idx) const
        {
                return mVtxs[idx];
        };

        unsigned int GetSize(void) const
        {
                return mVtxs.size();
        };

        void Clear(int reservesize)  // clear the vertice pool.
        {
                mVertSet.clear();
                mVtxs.clear();
                mVtxs.reserve(reservesize);
        };

        const VertexVector& GetVertexList(void) const { return mVtxs; };

        void Set(const Type& vtx)
        {
                mVtxs.push_back(vtx);
        }

        unsigned int GetVertexCount(void) const
        {
                return mVtxs.size();
        };


        Type * GetBuffer(void)
        {
                return &mVtxs[0];
        };

private:
        VertexSet      mVertSet; // ordered list.
        VertexVector   mVtxs;  // set of vertices.
};

double tmpp[3] = {0,0,0};
template<> VertexPosition VertexLess<VertexPosition>::mFind = tmpp;
template<> std::vector<VertexPosition > *VertexLess<VertexPosition>::mList =0;

enum RDIFF
{
  RD_EQUAL,
  RD_LESS,
  RD_GREATER
};

static RDIFF relativeDiff(const double *a,const double *b,double magnitude)
{
  RDIFF ret = RD_EQUAL;

  double m2 = magnitude*magnitude;
  double dx = a[0]-b[0];
  double dy = a[1]-b[1];
  double dz = a[2]-b[2];
  double d2 = (dx*dx)+(dy*dy)+(dz*dz);

  if ( d2 > m2 )
  {
         if ( a[0] < b[0] ) ret = RD_LESS;
    else if ( a[0] > b[0] ) ret = RD_GREATER;
    else if ( a[1] < b[1] ) ret = RD_LESS;
    else if ( a[1] > b[1] ) ret = RD_GREATER;
    else if ( a[2] < b[2] ) ret = RD_LESS;
    else if ( a[2] > b[2] ) ret = RD_GREATER;
  }
  return ret;
}


template<>
bool VertexLess<VertexPosition>::operator()(int v1,int v2) const
{
  bool ret = false;

        const VertexPosition& a = Get(v1);
        const VertexPosition& b = Get(v2);

  RDIFF d = relativeDiff(a.mPos,b.mPos,0.0001f);
  if ( d == RD_LESS ) ret = true;

  return ret;

};



VertexLookup Vl_createVertexLookup(void)
{
  VertexLookup ret = new VertexPool< VertexPosition >;
  return ret;
}

void          Vl_releaseVertexLookup(VertexLookup vlook)
{
  VertexPool< VertexPosition > *vp = (VertexPool< VertexPosition > *) vlook;
  delete vp;
}

unsigned int  Vl_getIndex(VertexLookup vlook,const double *pos)  // get index.
{
  VertexPool< VertexPosition > *vp = (VertexPool< VertexPosition > *) vlook;
  VertexPosition p(pos);
  return vp->GetVertex(p);
}

const double * Vl_getVertices(VertexLookup vlook)
{
  VertexPool< VertexPosition > *vp = (VertexPool< VertexPosition > *) vlook;
  return vp->GetPos(0);
}


unsigned int  Vl_getVcount(VertexLookup vlook)
{
  VertexPool< VertexPosition > *vp = (VertexPool< VertexPosition > *) vlook;
  return vp->GetVertexCount();
}

}; // end of namespace