src/hd/sm_del.c

/* Copyright (c) 1998 Silicon Graphics, Inc. */

#ifndef lint
static char SCCSid[] = "$SunId$ SGI";
#endif

/*
 *  sm_del.c
 */
#include "standard.h"

#include "sm_list.h"
#include "sm_geom.h"
#include "sm.h"

static EDGE Edges[MAX_EDGES];
static int Ecnt=0;


smLocator_remove_tri(sm,t_id)
SM *sm;
int t_id;
{
  STREE *st;
  char found;
  TRI *t;
  FVECT p0,p1,p2;

  st = SM_LOCATOR(sm);

  t = SM_NTH_TRI(sm,t_id);

  smDir(sm,p0,T_NTH_V(t,0));
  smDir(sm,p1,T_NTH_V(t,1));
  smDir(sm,p2,T_NTH_V(t,2));

  found = stRemove_tri(st,t_id,p0,p1,p2);

  return(found);
}

smFree_tri(sm,id)
SM *sm;
int id;
{
  TRI *tri;

  tri = SM_NTH_TRI(sm,id);
  /* Add to the free_list */
  T_NEXT_FREE(tri) = SM_FREE_TRIS(sm);
  SM_FREE_TRIS(sm) = id;
  T_VALID_FLAG(tri) = -1;
}

/* Assumes mesh pointers have been cleaned up appropriately: just deletes from
   Point location and triangle data structure
*/
smDelete_tri(sm,t_id)
SM *sm;
int t_id;
{

    /* first remove from point location structure */
    smLocator_remove_tri(sm,t_id);

  /* NOTE: Assumes that a new triangle adjacent to each vertex
     has been added- before the deletion: replacing
     the old tri- and therefore dont need to dereference any pointers
     to id because the vertices can no longer
     point to tri id as being the first triangle pointer
  */
  if(!SM_IS_NTH_T_BASE(sm,t_id))
  {
    SM_NUM_TRIS(sm)--;
    if(SM_IS_NTH_T_NEW(sm,t_id))
      smNew_tri_cnt--;
  }
  smClear_tri_flags(sm,t_id);

  smFree_tri(sm,t_id);

}


LIST
*smVertex_star_polygon(sm,id)
SM *sm;
int id;
{
    TRI *tri,*t_next;
    LIST *elist,*end,*tlist;
    int t_id,v_next,t_next_id;
    int e;

    elist = end =  NULL;
    /* Get the first triangle adjacent to vertex id */
    t_id = SM_NTH_VERT(sm,id);
    tri = SM_NTH_TRI(sm,t_id);

    
    if((e = eNew_edge()) == SM_INVALID)
    {
#ifdef DEBUG
        eputs("smVertex_star_polygon():Too many edges\n");
#endif
        return(NULL);
    }
    elist = add_data_to_circular_list(elist,&end,e);
    v_next = (T_WHICH_V(tri,id)+1)%3;
    SET_E_NTH_VERT(e,0,T_NTH_V(tri,v_next));
    SET_E_NTH_TRI(e,0,SM_INVALID);
    SET_E_NTH_TRI(e,1,T_NTH_NBR(tri,v_next));
    v_next = (T_WHICH_V(tri,id)+2)%3;
    SET_E_NTH_VERT(e,1,T_NTH_V(tri,v_next));

    
    t_next_id = t_id;
    t_next = tri;

    tlist = push_data(NULL,t_id);

    while((t_next_id = smTri_next_ccw_nbr(sm,t_next,id)) != t_id)
    {   
        if((e = eNew_edge()) == SM_INVALID)
        {
#ifdef DEBUG
            eputs("smVertex_star_polygon():Too many edges\n");
#endif
            return(NULL);
        }
        elist = add_data_to_circular_list(elist,&end,e);
        t_next = SM_NTH_TRI(sm,t_next_id);
        v_next = (T_WHICH_V(t_next,id)+1)%3;
        SET_E_NTH_VERT(e,0,T_NTH_V(t_next,v_next));
        SET_E_NTH_TRI(e,0,SM_INVALID);
        SET_E_NTH_TRI(e,1,T_NTH_NBR(t_next,v_next));
        v_next = (T_WHICH_V(t_next,id)+2)%3;
        SET_E_NTH_VERT(e,1,T_NTH_V(t_next,v_next));
        tlist = push_data(tlist,t_next_id);
    }
    while(tlist)
    {
        t_id = (int)pop_list(&tlist);
        smDelete_tri(sm,t_id);
    }
    return(elist);
}

int
smEdge_intersect_polygon(sm,v0,v1,l)
SM *sm;
FVECT v0,v1;
LIST *l;
{
    FVECT e0,e1;
    int e,id_e0,id_e1;
    LIST *el,*eptr;
    
    /* Test the edges in l against v0v1 to see if v0v1 intersects
       any other edges
     */
    
    el = l;

    while(el)
    {
      e = (int)LIST_DATA(el);
      id_e0 = E_NTH_VERT(e,0);
      id_e1 = E_NTH_VERT(e,1);

      smDir(sm,e0,id_e0);
      smDir(sm,e1,id_e1);
      if(spherical_polygon_edge_intersect(v0,v1,e0,e1))
        return(TRUE);

      el = LIST_NEXT(el);
      if(el == l)
        break;
    }
    return(FALSE);
}

int
smFind_next_convex_vertex(sm,id0,id1,v0,v1,l)
   SM *sm;
   int id0,id1;
   FVECT v0,v1;
   LIST *l;
{
    int e,id;
    LIST *el;
    FVECT v;

    /* starting with the end of edge at head of l, search sequentially for
      vertex v such that v0v1v is a convex angle, and the edge v1v does
      not intersect any other edges
   */
    id = SM_INVALID;
    el = l;
    while(id != id0)
    {
        e = (int)LIST_DATA(el);
        id = E_NTH_VERT(e,1);

        smDir(sm,v,id); 

        if(convex_angle(v0,v1,v) && !smEdge_intersect_polygon(sm,v1,v,l))
           return(id);
              
        el = LIST_NEXT(el);
        if(el == l)
           break;
    }
    return(SM_INVALID);
}

int
split_edge_list(id0,id_new,l,lnew)
int id0,id_new;
LIST **l,**lnew;
{
    LIST *list,*lptr,*end;
    int e,e1,e2,new_e;

    e2 = SM_INVALID;
    list = lptr = *l;

    if((new_e = eNew_edge())==SM_INVALID)
     {
#ifdef DEBUG
            eputs("split_edge_list():Too many edges\n");
#endif
         return(FALSE);
     }
    SET_E_NTH_VERT(new_e,0,id0);
    SET_E_NTH_VERT(new_e,1,id_new);
    SET_E_NTH_TRI(new_e,0,SM_INVALID);
    SET_E_NTH_TRI(new_e,1,SM_INVALID);
    
    while(e2 != id_new)
    {
        lptr = LIST_NEXT(lptr);
        e = (int)LIST_DATA(lptr);
        e2 = E_NTH_VERT(e,1);
        if(lptr == list)
        {
#ifdef DEBUG        
          eputs("split_edge_list():cant find vertex\n");
#endif
          *lnew = NULL;
          return(FALSE);
        }

    }
    end = lptr;
    lptr =  LIST_NEXT(lptr);
    list = add_data_to_circular_list(list,&end,-new_e);
    *lnew = list;

    /* now follow other cycle */

    list = lptr;
    e2 = SM_INVALID;
    while(e2 != id0)
    {
        lptr = LIST_NEXT(lptr);
        e = (int)LIST_DATA(lptr);
        e2 = E_NTH_VERT(e,1);
        if(lptr == list)
        {
#ifdef DEBUG        
          eputs("split_edge_list():cant find intial vertex\n");
#endif
          *l = NULL;
          return(FALSE);
        }

    }
    end = lptr;
    list = add_data_to_circular_list(list,&end,new_e);
    *l = list;
    return(TRUE);
}


LIST
*smTriangulate_convex(sm,plist)
SM *sm;
LIST *plist;
{
    TRI *tri;
    int t_id,e_id0,e_id1,e_id2;
    int v_id0,v_id1,v_id2;
    LIST *lptr;
    int cnt;

    lptr = plist;
    e_id0 = (int)LIST_DATA(lptr);
    v_id0 = E_NTH_VERT(e_id0,0);
    lptr = LIST_NEXT(lptr);
    while(LIST_NEXT(lptr) != plist)
    {
        e_id1 = (int)LIST_DATA(lptr);
        v_id1 = E_NTH_VERT(e_id1,0);
        v_id2 = E_NTH_VERT(e_id1,1);
        /* form a triangle for each triple of with v0 as base of star */
        t_id = smAdd_tri(sm,v_id0,v_id1,v_id2,&tri);
        /* add which pointer?*/

        lptr = LIST_NEXT(lptr);

        if(LIST_NEXT(lptr) != plist)
        {
            e_id2 = eNew_edge();
            SET_E_NTH_VERT(e_id2,0,v_id2);
            SET_E_NTH_VERT(e_id2,1,v_id0);
        }
        else
           e_id2 = (int)LIST_DATA(lptr);
         
        /* set appropriate tri for each edge*/ 
        SET_E_NTH_TRI(e_id0,0,t_id);
        SET_E_NTH_TRI(e_id1,0,t_id);
        SET_E_NTH_TRI(e_id2,0,t_id);

        e_id0 = -e_id2;
    }
    free_list(plist);
}

smTriangulate_elist(sm,plist)
SM *sm;
LIST *plist;
{
    LIST *l,*el1;
    FVECT v0,v1,v2;
    int id0,id1,id2,e,id_next;
    char flipped;
    int debug = TRUE;

    l = plist;
    
    while(l)
    {
        /* get v0,v1,v2 */
      e = (int)LIST_DATA(l);
      id0 = E_NTH_VERT(e,0);
      id1 = E_NTH_VERT(e,1);
      l = LIST_NEXT(l);
      e = (int)LIST_DATA(l);
      id2 = E_NTH_VERT(e,1);

      smDir(sm,v0,id0);
      smDir(sm,v1,id1);
      smDir(sm,v2,id2);
      /* determine if convex (left turn), or concave(right turn) angle */
      if(convex_angle(v0,v1,v2))
      {
        if(l == plist)
          break;
        else
          continue;
      }
      /* if concave: add edge and recurse on two sub polygons */
      id_next = smFind_next_convex_vertex(sm,id0,id1,v0,v1,LIST_NEXT(l));
      if(id_next == SM_INVALID)
      {
#ifdef DEBUG
          eputs("smTriangulate_elist():Unable to find convex vertex\n");
#endif
          return;
      }
      /* add edge */
      el1 = NULL;
      /* Split edge list l into two lists: one from id1-id_next-id1,
         and the next from id2-id_next-id2
      */
      debug = split_edge_list(id1,id_next,&l,&el1);
      /* Recurse and triangulate the two edge lists */
      if(debug)
        debug = smTriangulate_elist(sm,l);
      if(debug)
        debug = smTriangulate_elist(sm,el1);

      return(debug);
    }
    smTriangulate_convex(sm,plist);
    return(TRUE);
}

int
smTriangulate_polygon(sm,plist)
SM *sm;
LIST *plist;
{
    int e,id_t0,id_t1,e0,e1;
    TRI *t0,*t1;
    int test;
    
    test = smTriangulate_elist(sm,plist,NULL);

    if(!test)
       return(test);
    FOR_ALL_EDGES(e)
    {
        id_t0 = E_NTH_TRI(e,0);
        id_t1 = E_NTH_TRI(e,1);
        if((id_t0==SM_INVALID) || (id_t1==SM_INVALID))
        {
#ifdef DEBUG
           eputs("smTriangulate_polygon(): Unassigned edge neighbor\n");
#endif
            continue;
        }
        t0 = SM_NTH_TRI(sm,id_t0);
        t1 = SM_NTH_TRI(sm,id_t1);
        
        e0 = T_WHICH_V(t0,E_NTH_VERT(e,0));
        T_NTH_NBR(t0,e0) = id_t1;

        e1 = T_WHICH_V(t1,E_NTH_VERT(e,1));
        T_NTH_NBR(t1,e1) = id_t0;
    }
    return(test);
}

eIn_tri(e,t)
int e;
TRI *t;
{

  if(T_NTH_V(t,0)==E_NTH_VERT(e,0)) 
    return(T_NTH_V(t,1)==E_NTH_VERT(e,1)||T_NTH_V(t,2)==E_NTH_VERT(e,1));
  else
    if(T_NTH_V(t,1)==E_NTH_VERT(e,0))
      return(T_NTH_V(t,0)==E_NTH_VERT(e,1)||T_NTH_V(t,2)==E_NTH_VERT(e,1));
    else if(T_NTH_V(t,2)==E_NTH_VERT(e,0))
      return(T_NTH_V(t,0)==E_NTH_VERT(e,1)||T_NTH_V(t,1)==E_NTH_VERT(e,1));
  return(FALSE);
}
smFix_edges(sm)
   SM *sm;
{
    int e,id_t0,id_t1,e_new,e0,e1,e0_next,e1_next;
    TRI *t0,*t1,*nt0,*nt1;
    int i,id_v0,id_v1,id_v2,id_p,nid_t0,nid_t1;
    FVECT v0,v1,v2,p,np,v;

    FOR_ALL_EDGES(e)
    {
        id_t0 = E_NTH_TRI(e,0);
        id_t1 = E_NTH_TRI(e,1);
        if((id_t0==SM_INVALID) || (id_t1==SM_INVALID))
        {
#ifdef DEBUG
            eputs("smFix_edges: Unassigned edge nbr\n");
#endif
            continue;
        }
        t0 = SM_NTH_TRI(sm,id_t0);
        t1 = SM_NTH_TRI(sm,id_t1);
        
        e0 = T_WHICH_V(t0,E_NTH_VERT(e,0));
        e1 = T_WHICH_V(t1,E_NTH_VERT(-e,0));
        e0_next = (e0+2)%3;
        e1_next = (e1+2)%3;
        id_v0 = E_NTH_VERT(e,0);
        id_v1 = E_NTH_VERT(e,1);
        id_v2 = T_NTH_V(t0,e0_next);
        id_p = T_NTH_V(t1,e1_next);

        smDir(sm,v0,id_v0);
        smDir(sm,v1,id_v1);
        smDir(sm,v2,id_v2);
        
        VCOPY(p,SM_NTH_WV(sm,id_p));    
        VSUB(p,p,SM_VIEW_CENTER(sm));
        if(point_in_cone(p,v0,v1,v2))
        {
            smTris_swap_edge(sm,id_t0,id_t1,e0,e1,&nid_t0,&nid_t1);
            
            nt0 = SM_NTH_TRI(sm,nid_t0);
            nt1 = SM_NTH_TRI(sm,nid_t1);
            FOR_ALL_EDGES_FROM(e,i)
            {
              if(E_NTH_TRI(i,0)==id_t0 || E_NTH_TRI(i,0)==id_t1)
              {
                if(eIn_tri(i,nt0))
                  SET_E_NTH_TRI(i,0,nid_t0);
                else
                  SET_E_NTH_TRI(i,0,nid_t1);
              }

              if(E_NTH_TRI(i,1)==id_t0 || E_NTH_TRI(i,1)==id_t1)
              {
                if(eIn_tri(i,nt0))
                  SET_E_NTH_TRI(i,1,nid_t0);
                else
                  SET_E_NTH_TRI(i,1,nid_t1);
              }
            }
            id_t0 = nid_t0;
            id_t1 = nid_t1;
            e_new = eNew_edge();
            SET_E_NTH_VERT(e_new,0,id_p);
            SET_E_NTH_VERT(e_new,1,id_v2);
            SET_E_NTH_TRI(e_new,0,id_t0);
            SET_E_NTH_TRI(e_new,1,id_t1);
        }
    }

}

int
smMesh_remove_vertex(sm,id)
   SM *sm;
   int id;
{
    int tri;
    LIST *elist;
    int cnt,debug;
    /* generate list of vertices that form the boundary of the
       star polygon formed by vertex id and all of its adjacent
       triangles
     */
    eClear_edges();
    elist = smVertex_star_polygon(sm,id);
    if(!elist)
       return(FALSE);

    /* Triangulate spherical polygon */
    debug = smTriangulate_polygon(sm,elist);


    /* Fix up new triangles to be Delaunay */
    if(debug)
       smFix_edges(sm);

    return(TRUE);
}
   
/* Remove point from samples, and from mesh. Delete any triangles
   adjacent to the point and re-triangulate the hole
   Return TRUE is point found , FALSE otherwise
*/
int
smDelete_point(sm,id)
SM *sm;
int id;
{

    /* Remove the corresponding vertex from the mesh */
    smMesh_remove_vertex(sm,id);
    /* Free the sample point */
    smDelete_sample(sm,id);
    return(TRUE);
}


Revision:	3.1
Committed:	Wed Aug 19 17:45:24 1998 UTC (25 years, 8 months ago) by gwlarson
Content type:	text/plain
Branch:	MAIN
Log Message:	Initial revision
#	User	Rev	Content
1	gwlarson	3.1	/* Copyright (c) 1998 Silicon Graphics, Inc. */
2
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ SGI";
5			#endif
6
7			/*
8			* sm_del.c
9			*/
10			#include "standard.h"
11
12			#include "sm_list.h"
13			#include "sm_geom.h"
14			#include "sm.h"
15
16			static EDGE Edges[MAX_EDGES];
17			static int Ecnt=0;
18
19
20			smLocator_remove_tri(sm,t_id)
21			SM *sm;
22			int t_id;
23			{
24			STREE *st;
25			char found;
26			TRI *t;
27			FVECT p0,p1,p2;
28
29			st = SM_LOCATOR(sm);
30
31			t = SM_NTH_TRI(sm,t_id);
32
33			smDir(sm,p0,T_NTH_V(t,0));
34			smDir(sm,p1,T_NTH_V(t,1));
35			smDir(sm,p2,T_NTH_V(t,2));
36
37			found = stRemove_tri(st,t_id,p0,p1,p2);
38
39			return(found);
40			}
41
42			smFree_tri(sm,id)
43			SM *sm;
44			int id;
45			{
46			TRI *tri;
47
48			tri = SM_NTH_TRI(sm,id);
49			/* Add to the free_list */
50			T_NEXT_FREE(tri) = SM_FREE_TRIS(sm);
51			SM_FREE_TRIS(sm) = id;
52			T_VALID_FLAG(tri) = -1;
53			}
54
55			/* Assumes mesh pointers have been cleaned up appropriately: just deletes from
56			Point location and triangle data structure
57			*/
58			smDelete_tri(sm,t_id)
59			SM *sm;
60			int t_id;
61			{
62
63			/* first remove from point location structure */
64			smLocator_remove_tri(sm,t_id);
65
66			/* NOTE: Assumes that a new triangle adjacent to each vertex
67			has been added- before the deletion: replacing
68			the old tri- and therefore dont need to dereference any pointers
69			to id because the vertices can no longer
70			point to tri id as being the first triangle pointer
71			*/
72			if(!SM_IS_NTH_T_BASE(sm,t_id))
73			{
74			SM_NUM_TRIS(sm)--;
75			if(SM_IS_NTH_T_NEW(sm,t_id))
76			smNew_tri_cnt--;
77			}
78			smClear_tri_flags(sm,t_id);
79
80			smFree_tri(sm,t_id);
81
82			}
83
84
85
86			LIST
87			*smVertex_star_polygon(sm,id)
88			SM *sm;
89			int id;
90			{
91			TRI tri,t_next;
92			LIST elist,end,*tlist;
93			int t_id,v_next,t_next_id;
94			int e;
95
96			elist = end = NULL;
97			/* Get the first triangle adjacent to vertex id */
98			t_id = SM_NTH_VERT(sm,id);
99			tri = SM_NTH_TRI(sm,t_id);
100
101
102			if((e = eNew_edge()) == SM_INVALID)
103			{
104			#ifdef DEBUG
105			eputs("smVertex_star_polygon():Too many edges\n");
106			#endif
107			return(NULL);
108			}
109			elist = add_data_to_circular_list(elist,&end,e);
110			v_next = (T_WHICH_V(tri,id)+1)%3;
111			SET_E_NTH_VERT(e,0,T_NTH_V(tri,v_next));
112			SET_E_NTH_TRI(e,0,SM_INVALID);
113			SET_E_NTH_TRI(e,1,T_NTH_NBR(tri,v_next));
114			v_next = (T_WHICH_V(tri,id)+2)%3;
115			SET_E_NTH_VERT(e,1,T_NTH_V(tri,v_next));
116
117
118			t_next_id = t_id;
119			t_next = tri;
120
121			tlist = push_data(NULL,t_id);
122
123			while((t_next_id = smTri_next_ccw_nbr(sm,t_next,id)) != t_id)
124			{
125			if((e = eNew_edge()) == SM_INVALID)
126			{
127			#ifdef DEBUG
128			eputs("smVertex_star_polygon():Too many edges\n");
129			#endif
130			return(NULL);
131			}
132			elist = add_data_to_circular_list(elist,&end,e);
133			t_next = SM_NTH_TRI(sm,t_next_id);
134			v_next = (T_WHICH_V(t_next,id)+1)%3;
135			SET_E_NTH_VERT(e,0,T_NTH_V(t_next,v_next));
136			SET_E_NTH_TRI(e,0,SM_INVALID);
137			SET_E_NTH_TRI(e,1,T_NTH_NBR(t_next,v_next));
138			v_next = (T_WHICH_V(t_next,id)+2)%3;
139			SET_E_NTH_VERT(e,1,T_NTH_V(t_next,v_next));
140			tlist = push_data(tlist,t_next_id);
141			}
142			while(tlist)
143			{
144			t_id = (int)pop_list(&tlist);
145			smDelete_tri(sm,t_id);
146			}
147			return(elist);
148			}
149
150			int
151			smEdge_intersect_polygon(sm,v0,v1,l)
152			SM *sm;
153			FVECT v0,v1;
154			LIST *l;
155			{
156			FVECT e0,e1;
157			int e,id_e0,id_e1;
158			LIST el,eptr;
159
160			/* Test the edges in l against v0v1 to see if v0v1 intersects
161			any other edges
162			*/
163
164			el = l;
165
166			while(el)
167			{
168			e = (int)LIST_DATA(el);
169			id_e0 = E_NTH_VERT(e,0);
170			id_e1 = E_NTH_VERT(e,1);
171
172			smDir(sm,e0,id_e0);
173			smDir(sm,e1,id_e1);
174			if(spherical_polygon_edge_intersect(v0,v1,e0,e1))
175			return(TRUE);
176
177			el = LIST_NEXT(el);
178			if(el == l)
179			break;
180			}
181			return(FALSE);
182			}
183
184			int
185			smFind_next_convex_vertex(sm,id0,id1,v0,v1,l)
186			SM *sm;
187			int id0,id1;
188			FVECT v0,v1;
189			LIST *l;
190			{
191			int e,id;
192			LIST *el;
193			FVECT v;
194
195			/* starting with the end of edge at head of l, search sequentially for
196			vertex v such that v0v1v is a convex angle, and the edge v1v does
197			not intersect any other edges
198			*/
199			id = SM_INVALID;
200			el = l;
201			while(id != id0)
202			{
203			e = (int)LIST_DATA(el);
204			id = E_NTH_VERT(e,1);
205
206			smDir(sm,v,id);
207
208			if(convex_angle(v0,v1,v) && !smEdge_intersect_polygon(sm,v1,v,l))
209			return(id);
210
211			el = LIST_NEXT(el);
212			if(el == l)
213			break;
214			}
215			return(SM_INVALID);
216			}
217
218			int
219			split_edge_list(id0,id_new,l,lnew)
220			int id0,id_new;
221			LIST l,lnew;
222			{
223			LIST list,lptr,*end;
224			int e,e1,e2,new_e;
225
226			e2 = SM_INVALID;
227			list = lptr = *l;
228
229			if((new_e = eNew_edge())==SM_INVALID)
230			{
231			#ifdef DEBUG
232			eputs("split_edge_list():Too many edges\n");
233			#endif
234			return(FALSE);
235			}
236			SET_E_NTH_VERT(new_e,0,id0);
237			SET_E_NTH_VERT(new_e,1,id_new);
238			SET_E_NTH_TRI(new_e,0,SM_INVALID);
239			SET_E_NTH_TRI(new_e,1,SM_INVALID);
240
241			while(e2 != id_new)
242			{
243			lptr = LIST_NEXT(lptr);
244			e = (int)LIST_DATA(lptr);
245			e2 = E_NTH_VERT(e,1);
246			if(lptr == list)
247			{
248			#ifdef DEBUG
249			eputs("split_edge_list():cant find vertex\n");
250			#endif
251			*lnew = NULL;
252			return(FALSE);
253			}
254
255			}
256			end = lptr;
257			lptr = LIST_NEXT(lptr);
258			list = add_data_to_circular_list(list,&end,-new_e);
259			*lnew = list;
260
261			/* now follow other cycle */
262
263			list = lptr;
264			e2 = SM_INVALID;
265			while(e2 != id0)
266			{
267			lptr = LIST_NEXT(lptr);
268			e = (int)LIST_DATA(lptr);
269			e2 = E_NTH_VERT(e,1);
270			if(lptr == list)
271			{
272			#ifdef DEBUG
273			eputs("split_edge_list():cant find intial vertex\n");
274			#endif
275			*l = NULL;
276			return(FALSE);
277			}
278
279			}
280			end = lptr;
281			list = add_data_to_circular_list(list,&end,new_e);
282			*l = list;
283			return(TRUE);
284			}
285
286
287
288			LIST
289			*smTriangulate_convex(sm,plist)
290			SM *sm;
291			LIST *plist;
292			{
293			TRI *tri;
294			int t_id,e_id0,e_id1,e_id2;
295			int v_id0,v_id1,v_id2;
296			LIST *lptr;
297			int cnt;
298
299			lptr = plist;
300			e_id0 = (int)LIST_DATA(lptr);
301			v_id0 = E_NTH_VERT(e_id0,0);
302			lptr = LIST_NEXT(lptr);
303			while(LIST_NEXT(lptr) != plist)
304			{
305			e_id1 = (int)LIST_DATA(lptr);
306			v_id1 = E_NTH_VERT(e_id1,0);
307			v_id2 = E_NTH_VERT(e_id1,1);
308			/* form a triangle for each triple of with v0 as base of star */
309			t_id = smAdd_tri(sm,v_id0,v_id1,v_id2,&tri);
310			/* add which pointer?*/
311
312			lptr = LIST_NEXT(lptr);
313
314			if(LIST_NEXT(lptr) != plist)
315			{
316			e_id2 = eNew_edge();
317			SET_E_NTH_VERT(e_id2,0,v_id2);
318			SET_E_NTH_VERT(e_id2,1,v_id0);
319			}
320			else
321			e_id2 = (int)LIST_DATA(lptr);
322
323			/* set appropriate tri for each edge*/
324			SET_E_NTH_TRI(e_id0,0,t_id);
325			SET_E_NTH_TRI(e_id1,0,t_id);
326			SET_E_NTH_TRI(e_id2,0,t_id);
327
328			e_id0 = -e_id2;
329			}
330			free_list(plist);
331			}
332
333			smTriangulate_elist(sm,plist)
334			SM *sm;
335			LIST *plist;
336			{
337			LIST l,el1;
338			FVECT v0,v1,v2;
339			int id0,id1,id2,e,id_next;
340			char flipped;
341			int debug = TRUE;
342
343			l = plist;
344
345			while(l)
346			{
347			/* get v0,v1,v2 */
348			e = (int)LIST_DATA(l);
349			id0 = E_NTH_VERT(e,0);
350			id1 = E_NTH_VERT(e,1);
351			l = LIST_NEXT(l);
352			e = (int)LIST_DATA(l);
353			id2 = E_NTH_VERT(e,1);
354
355			smDir(sm,v0,id0);
356			smDir(sm,v1,id1);
357			smDir(sm,v2,id2);
358			/* determine if convex (left turn), or concave(right turn) angle */
359			if(convex_angle(v0,v1,v2))
360			{
361			if(l == plist)
362			break;
363			else
364			continue;
365			}
366			/* if concave: add edge and recurse on two sub polygons */
367			id_next = smFind_next_convex_vertex(sm,id0,id1,v0,v1,LIST_NEXT(l));
368			if(id_next == SM_INVALID)
369			{
370			#ifdef DEBUG
371			eputs("smTriangulate_elist():Unable to find convex vertex\n");
372			#endif
373			return;
374			}
375			/* add edge */
376			el1 = NULL;
377			/* Split edge list l into two lists: one from id1-id_next-id1,
378			and the next from id2-id_next-id2
379			*/
380			debug = split_edge_list(id1,id_next,&l,&el1);
381			/* Recurse and triangulate the two edge lists */
382			if(debug)
383			debug = smTriangulate_elist(sm,l);
384			if(debug)
385			debug = smTriangulate_elist(sm,el1);
386
387			return(debug);
388			}
389			smTriangulate_convex(sm,plist);
390			return(TRUE);
391			}
392
393			int
394			smTriangulate_polygon(sm,plist)
395			SM *sm;
396			LIST *plist;
397			{
398			int e,id_t0,id_t1,e0,e1;
399			TRI t0,t1;
400			int test;
401
402			test = smTriangulate_elist(sm,plist,NULL);
403
404			if(!test)
405			return(test);
406			FOR_ALL_EDGES(e)
407			{
408			id_t0 = E_NTH_TRI(e,0);
409			id_t1 = E_NTH_TRI(e,1);
410			if((id_t0==SM_INVALID) \|\| (id_t1==SM_INVALID))
411			{
412			#ifdef DEBUG
413			eputs("smTriangulate_polygon(): Unassigned edge neighbor\n");
414			#endif
415			continue;
416			}
417			t0 = SM_NTH_TRI(sm,id_t0);
418			t1 = SM_NTH_TRI(sm,id_t1);
419
420			e0 = T_WHICH_V(t0,E_NTH_VERT(e,0));
421			T_NTH_NBR(t0,e0) = id_t1;
422
423			e1 = T_WHICH_V(t1,E_NTH_VERT(e,1));
424			T_NTH_NBR(t1,e1) = id_t0;
425			}
426			return(test);
427			}
428
429			eIn_tri(e,t)
430			int e;
431			TRI *t;
432			{
433
434			if(T_NTH_V(t,0)==E_NTH_VERT(e,0))
435			return(T_NTH_V(t,1)==E_NTH_VERT(e,1)\|\|T_NTH_V(t,2)==E_NTH_VERT(e,1));
436			else
437			if(T_NTH_V(t,1)==E_NTH_VERT(e,0))
438			return(T_NTH_V(t,0)==E_NTH_VERT(e,1)\|\|T_NTH_V(t,2)==E_NTH_VERT(e,1));
439			else if(T_NTH_V(t,2)==E_NTH_VERT(e,0))
440			return(T_NTH_V(t,0)==E_NTH_VERT(e,1)\|\|T_NTH_V(t,1)==E_NTH_VERT(e,1));
441			return(FALSE);
442			}
443			smFix_edges(sm)
444			SM *sm;
445			{
446			int e,id_t0,id_t1,e_new,e0,e1,e0_next,e1_next;
447			TRI t0,t1,nt0,nt1;
448			int i,id_v0,id_v1,id_v2,id_p,nid_t0,nid_t1;
449			FVECT v0,v1,v2,p,np,v;
450
451			FOR_ALL_EDGES(e)
452			{
453			id_t0 = E_NTH_TRI(e,0);
454			id_t1 = E_NTH_TRI(e,1);
455			if((id_t0==SM_INVALID) \|\| (id_t1==SM_INVALID))
456			{
457			#ifdef DEBUG
458			eputs("smFix_edges: Unassigned edge nbr\n");
459			#endif
460			continue;
461			}
462			t0 = SM_NTH_TRI(sm,id_t0);
463			t1 = SM_NTH_TRI(sm,id_t1);
464
465			e0 = T_WHICH_V(t0,E_NTH_VERT(e,0));
466			e1 = T_WHICH_V(t1,E_NTH_VERT(-e,0));
467			e0_next = (e0+2)%3;
468			e1_next = (e1+2)%3;
469			id_v0 = E_NTH_VERT(e,0);
470			id_v1 = E_NTH_VERT(e,1);
471			id_v2 = T_NTH_V(t0,e0_next);
472			id_p = T_NTH_V(t1,e1_next);
473
474			smDir(sm,v0,id_v0);
475			smDir(sm,v1,id_v1);
476			smDir(sm,v2,id_v2);
477
478			VCOPY(p,SM_NTH_WV(sm,id_p));
479			VSUB(p,p,SM_VIEW_CENTER(sm));
480			if(point_in_cone(p,v0,v1,v2))
481			{
482			smTris_swap_edge(sm,id_t0,id_t1,e0,e1,&nid_t0,&nid_t1);
483
484			nt0 = SM_NTH_TRI(sm,nid_t0);
485			nt1 = SM_NTH_TRI(sm,nid_t1);
486			FOR_ALL_EDGES_FROM(e,i)
487			{
488			if(E_NTH_TRI(i,0)==id_t0 \|\| E_NTH_TRI(i,0)==id_t1)
489			{
490			if(eIn_tri(i,nt0))
491			SET_E_NTH_TRI(i,0,nid_t0);
492			else
493			SET_E_NTH_TRI(i,0,nid_t1);
494			}
495
496			if(E_NTH_TRI(i,1)==id_t0 \|\| E_NTH_TRI(i,1)==id_t1)
497			{
498			if(eIn_tri(i,nt0))
499			SET_E_NTH_TRI(i,1,nid_t0);
500			else
501			SET_E_NTH_TRI(i,1,nid_t1);
502			}
503			}
504			id_t0 = nid_t0;
505			id_t1 = nid_t1;
506			e_new = eNew_edge();
507			SET_E_NTH_VERT(e_new,0,id_p);
508			SET_E_NTH_VERT(e_new,1,id_v2);
509			SET_E_NTH_TRI(e_new,0,id_t0);
510			SET_E_NTH_TRI(e_new,1,id_t1);
511			}
512			}
513
514			}
515
516			int
517			smMesh_remove_vertex(sm,id)
518			SM *sm;
519			int id;
520			{
521			int tri;
522			LIST *elist;
523			int cnt,debug;
524			/* generate list of vertices that form the boundary of the
525			star polygon formed by vertex id and all of its adjacent
526			triangles
527			*/
528			eClear_edges();
529			elist = smVertex_star_polygon(sm,id);
530			if(!elist)
531			return(FALSE);
532
533			/* Triangulate spherical polygon */
534			debug = smTriangulate_polygon(sm,elist);
535
536
537			/* Fix up new triangles to be Delaunay */
538			if(debug)
539			smFix_edges(sm);
540
541			return(TRUE);
542			}
543
544			/* Remove point from samples, and from mesh. Delete any triangles
545			adjacent to the point and re-triangulate the hole
546			Return TRUE is point found , FALSE otherwise
547			*/
548			int
549			smDelete_point(sm,id)
550			SM *sm;
551			int id;
552			{
553
554			/* Remove the corresponding vertex from the mesh */
555			smMesh_remove_vertex(sm,id);
556			/* Free the sample point */
557			smDelete_sample(sm,id);
558			return(TRUE);
559			}
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