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/**

    @file 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++.

 */

#ifndef __GEOMETRY_POLYGONIZER_H

#define __GEOMETRY_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 int(gtriangles.size());

				}

			/** Ret urn number of vertices generated after the polygonization.

					Call this function only when march has been called. */

			int no_vertices() const

				{

					return int(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 int(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