core/vgl/internals/gpc.h

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/*
===========================================================================

Project:   Generic Polygon Clipper

           A new algorithm for calculating the difference, intersection,
           exclusive-or or union of arbitrary polygon sets.

File:      gpc.h
Author:    Alan Murta (email: gpc@cs.man.ac.uk)
Version:   2.32
Date:      17th December 2004

Copyright: (C) 1997-2004, Advanced Interfaces Group,
           University of Manchester.

           This software is free for non-commercial use. It may be copied,
           modified, and redistributed provided that this copyright notice
           is preserved on all copies. The intellectual property rights of
           the algorithms used reside with the University of Manchester
           Advanced Interfaces Group.

           You may not use this software, in whole or in part, in support
           of any commercial product without the express consent of the
           author.

           There is no warranty or other guarantee of fitness of this
           software for any purpose. It is provided solely "as is".

===========================================================================
*/

#ifndef gpc_h_
#define gpc_h_

#include <stdio.h>


/*
===========================================================================
                               Constants
===========================================================================
*/

/* Increase GPC_EPSILON to encourage merging of near coincident edges    */
/*                                                                       */
/* For example: #define GPC_EPSILON (DBL_EPSILON*1000000000)             */
#define GPC_EPSILON (DBL_EPSILON)

#define GPC_VERSION "2.32"


/*
===========================================================================
                           Public Data Types
===========================================================================
*/
#ifdef __cplusplus
extern "C" {
#endif

typedef enum                        /* Set operation type                */
{
  GPC_DIFF,                         /* Difference                        */
  GPC_INT,                          /* Intersection                      */
  GPC_XOR,                          /* Exclusive or                      */
  GPC_UNION                         /* Union                             */
} gpc_op;

typedef struct                      /* Polygon vertex structure          */
{
  double              x;            /* Vertex x component                */
  double              y;            /* vertex y component                */
} gpc_vertex;

typedef struct                      /* Vertex list structure             */
{
  int                 num_vertices; /* Number of vertices in list        */
  gpc_vertex         *vertex;       /* Vertex array pointer              */
} gpc_vertex_list;

typedef struct                      /* Polygon set structure             */
{
  int                 num_contours; /* Number of contours in polygon     */
  int                *hole;         /* Hole / external contour flags     */
  gpc_vertex_list    *contour;      /* Contour array pointer             */
} gpc_polygon;

typedef struct                      /* Tristrip set structure            */
{
  int                 num_strips;   /* Number of tristrips               */
  gpc_vertex_list    *strip;        /* Tristrip array pointer            */
} gpc_tristrip;


/*
===========================================================================
                       Public Function Prototypes
===========================================================================
*/

int  gpc_polygon_clip        (gpc_op           set_operation,
                              gpc_polygon     *subject_polygon,
                              gpc_polygon     *clip_polygon,
                              gpc_polygon     *result_polygon);

void gpc_free_polygon        (gpc_polygon     *polygon);

#if 0 /* These functions are not used in vgl_clip */ 

void gpc_read_polygon        (FILE            *infile_ptr, 
                              int              read_hole_flags,
                              gpc_polygon     *polygon);

void gpc_write_polygon       (FILE            *outfile_ptr,
                              int              write_hole_flags,
                              gpc_polygon     *polygon);

void gpc_add_contour         (gpc_polygon     *polygon,
                              gpc_vertex_list *contour,
                              int              hole);

void gpc_tristrip_clip       (gpc_op           set_operation,
                              gpc_polygon     *subject_polygon,
                              gpc_polygon     *clip_polygon,
                              gpc_tristrip    *result_tristrip);

void gpc_polygon_to_tristrip (gpc_polygon     *polygon,
                              gpc_tristrip    *tristrip);

void gpc_free_tristrip       (gpc_tristrip    *tristrip);

#endif /* 0 */

#ifdef __cplusplus
}
#endif

#endif /* gpc_h_ */

/*
===========================================================================
                           End of file: gpc.h
===========================================================================
*/