/*****************************************************************************
*   "Irit" - the 3d polygonal solid modeller.				     *
*									     *
* Written by:  Gershon Elber				Ver 0.2, Mar. 1990   *
******************************************************************************
*   Definitions, local to module, of the polygon convexity handler.	     *
*****************************************************************************/

#ifndef CONVEX_LH
#define CONVEX_LH

/* Used to hold edges (V | V -> Pnext) that intersect with level y = Ylevel. */
typedef struct InterYVrtxList {
    ByteType InterYType;
    struct VertexStruct *V;
    struct InterYVrtxList *Pnext;
} InterYVrtxList;

#define	INTER_Y_NONE	0		       /* Y level intersection type. */
#define	INTER_Y_START	1
#define	INTER_Y_MIDDLE	2

#define LOOP_ABOVE_Y	0      /* Type of open loops extracted from polygon. */
#define LOOP_BELOW_Y	1

/* Used to sort and combine the polygons above Ylevel together if possible.  */
typedef struct SortPolysInX {
    struct VertexStruct *VMinX, *VMaxX;
    int Reverse; 	 /* If TRUE than VMinX vertex is AFTER VMaxX vertex. */
} SortPolysInX;

/* The following are temporary flags used to mark vertices that were visited */
/* by the loop tracing, at list once. As each vertex may be visited two at   */
/* the most (as starting & as end point of open loop), this is enough.	     */
/* INTER_TAG is used to mark vertices that created brand new with intersected*/
/* with the line y = Ylevel. Those are used to detect INTERNAL edges - if    */
/* at list one end of it is INTER_TAG, that edge is INTERNAL (see Irit.h).   */
#define INTER_TAG   0x40
#define VISITED_TAG 0x80

#define	IS_INTER_VRTX(Vrtx)	((Vrtx)->Tags & INTER_TAG)
#define	SET_INTER_VRTX(Vrtx)	((Vrtx)->Tags |= INTER_TAG)
#define	RST_INTER_VRTX(Vrtx)	((Vrtx)->Tags &= ~INTER_TAG)

#define	IS_VISITED_VRTX(Vrtx)	((Vrtx)->Tags & VISITED_TAG)
#define	SET_VISITED_VRTX(Vrtx)	((Vrtx)->Tags |= VISITED_TAG)
#define	RST_VISITED_VRTX(Vrtx)	((Vrtx)->Tags &= ~VISITED_TAG)


#endif /* CONVEX_LH */