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/**********************************************************************

polygonizer.h

This is Jules Bloomenthal's implicit surface polygonizer from GRAPHICS 
GEMS IV. Bloomenthal's polygonizer is still used and the present code
is simply the original code morphed into C++.

J. Andreas Bærentzen 2003.

**********************************************************************/

#ifndef POLYGONIZER_H
#define POLYGONIZER_H

#include <vector>

namespace Geometry
{

        enum ToTetraHedralize
                {
                        TET = 0,  // use tetrahedral decomposition 
                        NOTET = 1  // no tetrahedral decomposition  */
                };

        /** \brief Implicit function.

        The implicit function class represents the implicit function we wish 
                        to polygonize. Derive a class from this one and implement your 
                        implicit primitive in the eval function. Eval takes x,y,z coordinates and
                        returns a value. We assume that the surface is the zero level set 
                        and that the negative values are outside. This an arbitrary choice
                        which does not make the code less general. */
        class ImplicitFunction
                {
                public:
                        virtual float eval(float,float,float) = 0;
                };

        struct POINT { float x, y, z;   };

        typedef POINT VERTEX;
        typedef POINT NORMAL;

        /** TRIANGLE struct contains the indices of the vertices comprising 
                        the triangle */
        struct TRIANGLE
        {
                int v0,v1,v2;
        };

        /** \brief Polygonizer is the class used to perform polygonization.*/
        class Polygonizer
                {
                        std::vector<NORMAL> gnormals;  
                        std::vector<VERTEX> gvertices;  
                        std::vector<TRIANGLE> gtriangles;
  
                        ImplicitFunction* func;
                        float size;
                        int bounds;
                        
                        bool use_tetra;
                        bool use_normals;

                public: 
        
                        /** Constructor of Polygonizer. The first argument is the 
                                        ImplicitFunction that we wish to polygonize. The second
                                        argument is the size of the polygonizing cell. 
                                        The third arg. is the limit to how far away we will
                                        look for components of the implicit surface. 
                                        the fourth argument indicates whether the polygonizing cell
                                        is a tetrahedron (true) or cube (false). The final argument
                                        indicates whether normals should be computed.
                        */
                        Polygonizer(ImplicitFunction* _func, float _size, int _bounds,
                                                                        bool _use_tetra=false,
                                                                        bool _use_normals=false):
                                func(_func), size(_size), bounds(_bounds),
                                use_tetra(_use_tetra),
                                use_normals(_use_normals) {}

                        /** March erases the triangles gathered so far and builds a new 
                                        polygonization.  The  x,y,z 
                                        arguments indicate a point near the surface. */
                        void march(float x, float y, float z);

                        /** Return number of triangles generated after the polygonization.
                                        Call this function only when march has been called. */
                        int no_triangles() const
                                {
                                        return gtriangles.size();
                                }

                        /** Return number of vertices generated after the polygonization.
                                        Call this function only when march has been called. */
                        int no_vertices() const
                                {
                                        return gvertices.size();
                                }
        
                        /** Return number of normals generated after the polygonization.
                                        Of course the result of calling this function is the same as
                                        no_vertices.
                                        Call this function only when march has been called. */
                        int no_normals() const
                                {
                                        return gnormals.size();
                                }
        
                        /// Return triangle with index i. 
                                TRIANGLE& get_triangle(int i) 
                                        {
                                                return gtriangles[i];
                                        }

                                /// Return vertex with index i. 
                                        VERTEX& get_vertex(int i) 
                                                {
                                                        return gvertices[i];
                                                }
        
        
                                        /// Return normal with index i. 
                                                NORMAL& get_normal(int i) 
                                                        {
                                                                return gnormals[i];
                                                        }


                };
}

#endif