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;

int
remove_tri(qtptr,fptr,t_id)
   QUADTREE *qtptr;
   int *fptr;
   int t_id;
{
    OBJECT tset[QT_MAXSET+1];   
    int n;

   if(QT_IS_EMPTY(*qtptr))
     return(FALSE);
   /* remove id from set */
      else
      {
         if(!qtinset(*qtptr,t_id))
           return(FALSE);
         n = QT_SET_CNT(qtqueryset(*qtptr))-1;
         *qtptr = qtdelelem(*qtptr,t_id);
          if(n  == 0)
             (*fptr) |= QT_COMPRESS;
        if(!QT_FLAG_FILL_TRI(*fptr))
          (*fptr)++;
      }
    return(TRUE);
}

int
remove_tri_compress(qtptr,q0,q1,q2,t0,t1,t2,n,arg,t_id)
QUADTREE *qtptr;
FVECT q0,q1,q2;
FVECT t0,t1,t2;
int n;
int *arg;
int t_id;
{
    int f = 0;
    /* NOTE compress */
    return(remove_tri(qtptr,&f,t_id));
}


int
stDelete_tri(st,t_id,t0,t1,t2)
   STREE *st;
   int t_id;
   FVECT t0,t1,t2;
{
    int f;
    FVECT dir;
    
  /* First add all of the leaf cells lying on the triangle perimeter:
     mark all cells seen on the way
   */
    ST_CLEAR_FLAGS(st);
    f = 0;
    VSUB(dir,t1,t0);
    stTrace_edge(st,t0,dir,1.0,remove_tri,&f,t_id);
    VSUB(dir,t2,t1);
    stTrace_edge(st,t1,dir,1.0,remove_tri,&f,t_id);
    VSUB(dir,t0,t2);
    stTrace_edge(st,t2,dir,1.0,remove_tri,&f,t_id);
    /* Now visit interior */
    if(QT_FLAG_FILL_TRI(f) || QT_FLAG_UPDATE(f))
       stVisit_tri_interior(st,t0,t1,t2,remove_tri_compress,&f,t_id);
}


smLocator_remove_tri(sm,t_id)
SM *sm;
int t_id;
{
  STREE *st;
  char found;
  TRI *t;
  FVECT v0,v1,v2;

  st = SM_LOCATOR(sm);

  t = SM_NTH_TRI(sm,t_id);

  VSUB(v0,SM_T_NTH_WV(sm,t,0),SM_VIEW_CENTER(sm));
  VSUB(v1,SM_T_NTH_WV(sm,t,1),SM_VIEW_CENTER(sm));
  VSUB(v2,SM_T_NTH_WV(sm,t,2),SM_VIEW_CENTER(sm));
  found = stUpdate_tri(st,t_id,v0,v1,v2,remove_tri,remove_tri_compress);
  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;
{


  /* 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);
        /* first remove from point location structure */
        smLocator_remove_tri(sm,t_id);
        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);
      /* NOTE: DO these need to be normalized? Just subtract center? */
      smDir(sm,e0,id_e0);
      smDir(sm,e1,id_e1);
      if(sedge_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);
}


int
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);
        smLocator_add_tri(sm,t_id,v_id0,v_id1,v_id2);
        /* 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);
    return(TRUE);
}
int
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 done;

    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(FALSE);
      }
      /* 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
      */
      split_edge_list(id1,id_next,&l,&el1);
      /* Recurse and triangulate the two edge lists */
      done = smTriangulate_elist(sm,l);
      if(done)
        done = smTriangulate_elist(sm,el1);
      return(done);
    }
    done = smTriangulate_convex(sm,plist);
    return(done);
}

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

    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(): 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;
    LIST *add,*del;
    
    add = del = NULL;
    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,&add,&del);
            
            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);
        }
    }
    smUpdate_locator(sm,add,del);
}

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 */
    smTriangulate(sm,elist);


    /* Fix up new triangles to be Delaunay */
    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:	3.3
Committed:	Fri Sep 11 11:52:25 1998 UTC (25 years, 7 months ago) by gwlarson
Content type:	text/plain
Branch:	MAIN
Changes since 3.2:	+93 -30 lines
Log Message:	fixed triangle insertion using edge tracing
#	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	gwlarson	3.3	int
20			remove_tri(qtptr,fptr,t_id)
21			QUADTREE *qtptr;
22			int *fptr;
23			int t_id;
24			{
25			OBJECT tset[QT_MAXSET+1];
26			int n;
27	gwlarson	3.1
28	gwlarson	3.3	if(QT_IS_EMPTY(*qtptr))
29			return(FALSE);
30			/* remove id from set */
31			else
32			{
33			if(!qtinset(*qtptr,t_id))
34			return(FALSE);
35			n = QT_SET_CNT(qtqueryset(*qtptr))-1;
36			qtptr = qtdelelem(qtptr,t_id);
37			if(n == 0)
38			(*fptr) \|= QT_COMPRESS;
39			if(!QT_FLAG_FILL_TRI(*fptr))
40			(*fptr)++;
41			}
42			return(TRUE);
43			}
44
45			int
46			remove_tri_compress(qtptr,q0,q1,q2,t0,t1,t2,n,arg,t_id)
47			QUADTREE *qtptr;
48			FVECT q0,q1,q2;
49			FVECT t0,t1,t2;
50			int n;
51			int *arg;
52			int t_id;
53			{
54			int f = 0;
55			/* NOTE compress */
56			return(remove_tri(qtptr,&f,t_id));
57			}
58
59
60
61			int
62			stDelete_tri(st,t_id,t0,t1,t2)
63			STREE *st;
64			int t_id;
65			FVECT t0,t1,t2;
66			{
67			int f;
68			FVECT dir;
69
70			/* First add all of the leaf cells lying on the triangle perimeter:
71			mark all cells seen on the way
72			*/
73			ST_CLEAR_FLAGS(st);
74			f = 0;
75			VSUB(dir,t1,t0);
76			stTrace_edge(st,t0,dir,1.0,remove_tri,&f,t_id);
77			VSUB(dir,t2,t1);
78			stTrace_edge(st,t1,dir,1.0,remove_tri,&f,t_id);
79			VSUB(dir,t0,t2);
80			stTrace_edge(st,t2,dir,1.0,remove_tri,&f,t_id);
81			/* Now visit interior */
82			if(QT_FLAG_FILL_TRI(f) \|\| QT_FLAG_UPDATE(f))
83			stVisit_tri_interior(st,t0,t1,t2,remove_tri_compress,&f,t_id);
84			}
85
86
87	gwlarson	3.1	smLocator_remove_tri(sm,t_id)
88			SM *sm;
89			int t_id;
90			{
91			STREE *st;
92			char found;
93			TRI *t;
94	gwlarson	3.3	FVECT v0,v1,v2;
95	gwlarson	3.1
96			st = SM_LOCATOR(sm);
97
98			t = SM_NTH_TRI(sm,t_id);
99
100	gwlarson	3.3	VSUB(v0,SM_T_NTH_WV(sm,t,0),SM_VIEW_CENTER(sm));
101			VSUB(v1,SM_T_NTH_WV(sm,t,1),SM_VIEW_CENTER(sm));
102			VSUB(v2,SM_T_NTH_WV(sm,t,2),SM_VIEW_CENTER(sm));
103			found = stUpdate_tri(st,t_id,v0,v1,v2,remove_tri,remove_tri_compress);
104	gwlarson	3.1	return(found);
105			}
106
107			smFree_tri(sm,id)
108			SM *sm;
109			int id;
110			{
111			TRI *tri;
112
113			tri = SM_NTH_TRI(sm,id);
114			/* Add to the free_list */
115			T_NEXT_FREE(tri) = SM_FREE_TRIS(sm);
116			SM_FREE_TRIS(sm) = id;
117			T_VALID_FLAG(tri) = -1;
118			}
119
120			/* Assumes mesh pointers have been cleaned up appropriately: just deletes from
121			Point location and triangle data structure
122			*/
123			smDelete_tri(sm,t_id)
124			SM *sm;
125			int t_id;
126			{
127
128
129			/* NOTE: Assumes that a new triangle adjacent to each vertex
130			has been added- before the deletion: replacing
131			the old tri- and therefore dont need to dereference any pointers
132			to id because the vertices can no longer
133			point to tri id as being the first triangle pointer
134			*/
135			if(!SM_IS_NTH_T_BASE(sm,t_id))
136			{
137			SM_NUM_TRIS(sm)--;
138			if(SM_IS_NTH_T_NEW(sm,t_id))
139			smNew_tri_cnt--;
140			}
141			smClear_tri_flags(sm,t_id);
142
143			smFree_tri(sm,t_id);
144
145			}
146
147
148
149			LIST
150			*smVertex_star_polygon(sm,id)
151			SM *sm;
152			int id;
153			{
154			TRI tri,t_next;
155			LIST elist,end,*tlist;
156			int t_id,v_next,t_next_id;
157			int e;
158
159			elist = end = NULL;
160			/* Get the first triangle adjacent to vertex id */
161			t_id = SM_NTH_VERT(sm,id);
162			tri = SM_NTH_TRI(sm,t_id);
163
164
165			if((e = eNew_edge()) == SM_INVALID)
166			{
167			#ifdef DEBUG
168			eputs("smVertex_star_polygon():Too many edges\n");
169			#endif
170			return(NULL);
171			}
172			elist = add_data_to_circular_list(elist,&end,e);
173			v_next = (T_WHICH_V(tri,id)+1)%3;
174			SET_E_NTH_VERT(e,0,T_NTH_V(tri,v_next));
175			SET_E_NTH_TRI(e,0,SM_INVALID);
176			SET_E_NTH_TRI(e,1,T_NTH_NBR(tri,v_next));
177			v_next = (T_WHICH_V(tri,id)+2)%3;
178			SET_E_NTH_VERT(e,1,T_NTH_V(tri,v_next));
179
180
181			t_next_id = t_id;
182			t_next = tri;
183
184			tlist = push_data(NULL,t_id);
185
186			while((t_next_id = smTri_next_ccw_nbr(sm,t_next,id)) != t_id)
187			{
188			if((e = eNew_edge()) == SM_INVALID)
189			{
190			#ifdef DEBUG
191			eputs("smVertex_star_polygon():Too many edges\n");
192			#endif
193			return(NULL);
194			}
195			elist = add_data_to_circular_list(elist,&end,e);
196			t_next = SM_NTH_TRI(sm,t_next_id);
197			v_next = (T_WHICH_V(t_next,id)+1)%3;
198			SET_E_NTH_VERT(e,0,T_NTH_V(t_next,v_next));
199			SET_E_NTH_TRI(e,0,SM_INVALID);
200			SET_E_NTH_TRI(e,1,T_NTH_NBR(t_next,v_next));
201			v_next = (T_WHICH_V(t_next,id)+2)%3;
202			SET_E_NTH_VERT(e,1,T_NTH_V(t_next,v_next));
203			tlist = push_data(tlist,t_next_id);
204			}
205			while(tlist)
206			{
207			t_id = (int)pop_list(&tlist);
208	gwlarson	3.2	/* first remove from point location structure */
209			smLocator_remove_tri(sm,t_id);
210	gwlarson	3.1	smDelete_tri(sm,t_id);
211			}
212			return(elist);
213			}
214
215			int
216			smEdge_intersect_polygon(sm,v0,v1,l)
217			SM *sm;
218			FVECT v0,v1;
219			LIST *l;
220			{
221			FVECT e0,e1;
222			int e,id_e0,id_e1;
223			LIST el,eptr;
224
225			/* Test the edges in l against v0v1 to see if v0v1 intersects
226			any other edges
227			*/
228
229			el = l;
230
231			while(el)
232			{
233			e = (int)LIST_DATA(el);
234			id_e0 = E_NTH_VERT(e,0);
235			id_e1 = E_NTH_VERT(e,1);
236	gwlarson	3.3	/* NOTE: DO these need to be normalized? Just subtract center? */
237	gwlarson	3.1	smDir(sm,e0,id_e0);
238			smDir(sm,e1,id_e1);
239	gwlarson	3.3	if(sedge_intersect(v0,v1,e0,e1))
240	gwlarson	3.1	return(TRUE);
241
242			el = LIST_NEXT(el);
243			if(el == l)
244			break;
245			}
246			return(FALSE);
247			}
248
249			int
250			smFind_next_convex_vertex(sm,id0,id1,v0,v1,l)
251			SM *sm;
252			int id0,id1;
253			FVECT v0,v1;
254			LIST *l;
255			{
256			int e,id;
257			LIST *el;
258			FVECT v;
259
260			/* starting with the end of edge at head of l, search sequentially for
261			vertex v such that v0v1v is a convex angle, and the edge v1v does
262			not intersect any other edges
263			*/
264			id = SM_INVALID;
265			el = l;
266			while(id != id0)
267			{
268			e = (int)LIST_DATA(el);
269			id = E_NTH_VERT(e,1);
270
271			smDir(sm,v,id);
272
273			if(convex_angle(v0,v1,v) && !smEdge_intersect_polygon(sm,v1,v,l))
274			return(id);
275
276			el = LIST_NEXT(el);
277			if(el == l)
278			break;
279			}
280			return(SM_INVALID);
281			}
282
283			int
284			split_edge_list(id0,id_new,l,lnew)
285			int id0,id_new;
286			LIST l,lnew;
287			{
288			LIST list,lptr,*end;
289			int e,e1,e2,new_e;
290
291			e2 = SM_INVALID;
292			list = lptr = *l;
293
294			if((new_e = eNew_edge())==SM_INVALID)
295			{
296			#ifdef DEBUG
297			eputs("split_edge_list():Too many edges\n");
298			#endif
299			return(FALSE);
300			}
301			SET_E_NTH_VERT(new_e,0,id0);
302			SET_E_NTH_VERT(new_e,1,id_new);
303			SET_E_NTH_TRI(new_e,0,SM_INVALID);
304			SET_E_NTH_TRI(new_e,1,SM_INVALID);
305
306			while(e2 != id_new)
307			{
308			lptr = LIST_NEXT(lptr);
309			e = (int)LIST_DATA(lptr);
310			e2 = E_NTH_VERT(e,1);
311			if(lptr == list)
312			{
313			#ifdef DEBUG
314			eputs("split_edge_list():cant find vertex\n");
315			#endif
316			*lnew = NULL;
317			return(FALSE);
318			}
319
320			}
321			end = lptr;
322			lptr = LIST_NEXT(lptr);
323			list = add_data_to_circular_list(list,&end,-new_e);
324			*lnew = list;
325
326			/* now follow other cycle */
327
328			list = lptr;
329			e2 = SM_INVALID;
330			while(e2 != id0)
331			{
332			lptr = LIST_NEXT(lptr);
333			e = (int)LIST_DATA(lptr);
334			e2 = E_NTH_VERT(e,1);
335			if(lptr == list)
336			{
337			#ifdef DEBUG
338			eputs("split_edge_list():cant find intial vertex\n");
339			#endif
340			*l = NULL;
341			return(FALSE);
342			}
343
344			}
345			end = lptr;
346			list = add_data_to_circular_list(list,&end,new_e);
347			*l = list;
348			return(TRUE);
349			}
350
351
352	gwlarson	3.3	int
353			smTriangulate_convex(sm,plist)
354	gwlarson	3.1	SM *sm;
355			LIST *plist;
356			{
357			TRI *tri;
358			int t_id,e_id0,e_id1,e_id2;
359			int v_id0,v_id1,v_id2;
360			LIST *lptr;
361			int cnt;
362
363			lptr = plist;
364			e_id0 = (int)LIST_DATA(lptr);
365			v_id0 = E_NTH_VERT(e_id0,0);
366			lptr = LIST_NEXT(lptr);
367			while(LIST_NEXT(lptr) != plist)
368			{
369			e_id1 = (int)LIST_DATA(lptr);
370			v_id1 = E_NTH_VERT(e_id1,0);
371			v_id2 = E_NTH_VERT(e_id1,1);
372			/* form a triangle for each triple of with v0 as base of star */
373			t_id = smAdd_tri(sm,v_id0,v_id1,v_id2,&tri);
374	gwlarson	3.2	smLocator_add_tri(sm,t_id,v_id0,v_id1,v_id2);
375	gwlarson	3.1	/* add which pointer?*/
376
377			lptr = LIST_NEXT(lptr);
378
379			if(LIST_NEXT(lptr) != plist)
380			{
381			e_id2 = eNew_edge();
382			SET_E_NTH_VERT(e_id2,0,v_id2);
383			SET_E_NTH_VERT(e_id2,1,v_id0);
384			}
385			else
386			e_id2 = (int)LIST_DATA(lptr);
387
388			/* set appropriate tri for each edge*/
389			SET_E_NTH_TRI(e_id0,0,t_id);
390			SET_E_NTH_TRI(e_id1,0,t_id);
391			SET_E_NTH_TRI(e_id2,0,t_id);
392
393			e_id0 = -e_id2;
394			}
395	gwlarson	3.3
396	gwlarson	3.1	free_list(plist);
397	gwlarson	3.3	return(TRUE);
398	gwlarson	3.1	}
399	gwlarson	3.3	int
400	gwlarson	3.1	smTriangulate_elist(sm,plist)
401			SM *sm;
402			LIST *plist;
403			{
404			LIST l,el1;
405			FVECT v0,v1,v2;
406			int id0,id1,id2,e,id_next;
407			char flipped;
408	gwlarson	3.3	int done;
409	gwlarson	3.1
410			l = plist;
411
412			while(l)
413			{
414			/* get v0,v1,v2 */
415			e = (int)LIST_DATA(l);
416			id0 = E_NTH_VERT(e,0);
417			id1 = E_NTH_VERT(e,1);
418			l = LIST_NEXT(l);
419			e = (int)LIST_DATA(l);
420			id2 = E_NTH_VERT(e,1);
421
422			smDir(sm,v0,id0);
423			smDir(sm,v1,id1);
424			smDir(sm,v2,id2);
425			/* determine if convex (left turn), or concave(right turn) angle */
426			if(convex_angle(v0,v1,v2))
427			{
428			if(l == plist)
429			break;
430			else
431			continue;
432			}
433			/* if concave: add edge and recurse on two sub polygons */
434			id_next = smFind_next_convex_vertex(sm,id0,id1,v0,v1,LIST_NEXT(l));
435			if(id_next == SM_INVALID)
436			{
437			#ifdef DEBUG
438			eputs("smTriangulate_elist():Unable to find convex vertex\n");
439			#endif
440	gwlarson	3.3	return(FALSE);
441	gwlarson	3.1	}
442			/* add edge */
443			el1 = NULL;
444			/* Split edge list l into two lists: one from id1-id_next-id1,
445			and the next from id2-id_next-id2
446			*/
447	gwlarson	3.3	split_edge_list(id1,id_next,&l,&el1);
448	gwlarson	3.1	/* Recurse and triangulate the two edge lists */
449	gwlarson	3.3	done = smTriangulate_elist(sm,l);
450			if(done)
451			done = smTriangulate_elist(sm,el1);
452			return(done);
453	gwlarson	3.1	}
454	gwlarson	3.3	done = smTriangulate_convex(sm,plist);
455			return(done);
456	gwlarson	3.1	}
457
458			int
459	gwlarson	3.3	smTriangulate(sm,plist)
460	gwlarson	3.1	SM *sm;
461			LIST *plist;
462			{
463			int e,id_t0,id_t1,e0,e1;
464			TRI t0,t1;
465			int test;
466
467	gwlarson	3.3	test = smTriangulate_elist(sm,plist);
468	gwlarson	3.1
469			if(!test)
470			return(test);
471			FOR_ALL_EDGES(e)
472			{
473			id_t0 = E_NTH_TRI(e,0);
474			id_t1 = E_NTH_TRI(e,1);
475			if((id_t0==SM_INVALID) \|\| (id_t1==SM_INVALID))
476			{
477			#ifdef DEBUG
478	gwlarson	3.3	eputs("smTriangulate(): Unassigned edge neighbor\n");
479	gwlarson	3.1	#endif
480			continue;
481			}
482			t0 = SM_NTH_TRI(sm,id_t0);
483			t1 = SM_NTH_TRI(sm,id_t1);
484
485			e0 = T_WHICH_V(t0,E_NTH_VERT(e,0));
486			T_NTH_NBR(t0,e0) = id_t1;
487
488			e1 = T_WHICH_V(t1,E_NTH_VERT(e,1));
489			T_NTH_NBR(t1,e1) = id_t0;
490			}
491			return(test);
492			}
493
494			eIn_tri(e,t)
495			int e;
496			TRI *t;
497			{
498
499			if(T_NTH_V(t,0)==E_NTH_VERT(e,0))
500			return(T_NTH_V(t,1)==E_NTH_VERT(e,1)\|\|T_NTH_V(t,2)==E_NTH_VERT(e,1));
501			else
502			if(T_NTH_V(t,1)==E_NTH_VERT(e,0))
503			return(T_NTH_V(t,0)==E_NTH_VERT(e,1)\|\|T_NTH_V(t,2)==E_NTH_VERT(e,1));
504			else if(T_NTH_V(t,2)==E_NTH_VERT(e,0))
505			return(T_NTH_V(t,0)==E_NTH_VERT(e,1)\|\|T_NTH_V(t,1)==E_NTH_VERT(e,1));
506			return(FALSE);
507			}
508			smFix_edges(sm)
509			SM *sm;
510			{
511			int e,id_t0,id_t1,e_new,e0,e1,e0_next,e1_next;
512			TRI t0,t1,nt0,nt1;
513			int i,id_v0,id_v1,id_v2,id_p,nid_t0,nid_t1;
514			FVECT v0,v1,v2,p,np,v;
515	gwlarson	3.2	LIST add,del;
516
517			add = del = NULL;
518	gwlarson	3.1	FOR_ALL_EDGES(e)
519			{
520			id_t0 = E_NTH_TRI(e,0);
521			id_t1 = E_NTH_TRI(e,1);
522			if((id_t0==SM_INVALID) \|\| (id_t1==SM_INVALID))
523			{
524			#ifdef DEBUG
525			eputs("smFix_edges: Unassigned edge nbr\n");
526			#endif
527			continue;
528			}
529			t0 = SM_NTH_TRI(sm,id_t0);
530			t1 = SM_NTH_TRI(sm,id_t1);
531
532			e0 = T_WHICH_V(t0,E_NTH_VERT(e,0));
533			e1 = T_WHICH_V(t1,E_NTH_VERT(-e,0));
534			e0_next = (e0+2)%3;
535			e1_next = (e1+2)%3;
536			id_v0 = E_NTH_VERT(e,0);
537			id_v1 = E_NTH_VERT(e,1);
538			id_v2 = T_NTH_V(t0,e0_next);
539			id_p = T_NTH_V(t1,e1_next);
540
541			smDir(sm,v0,id_v0);
542			smDir(sm,v1,id_v1);
543			smDir(sm,v2,id_v2);
544
545			VCOPY(p,SM_NTH_WV(sm,id_p));
546			VSUB(p,p,SM_VIEW_CENTER(sm));
547			if(point_in_cone(p,v0,v1,v2))
548			{
549	gwlarson	3.2	smTris_swap_edge(sm,id_t0,id_t1,e0,e1,&nid_t0,&nid_t1,&add,&del);
550	gwlarson	3.1
551			nt0 = SM_NTH_TRI(sm,nid_t0);
552			nt1 = SM_NTH_TRI(sm,nid_t1);
553			FOR_ALL_EDGES_FROM(e,i)
554			{
555			if(E_NTH_TRI(i,0)==id_t0 \|\| E_NTH_TRI(i,0)==id_t1)
556			{
557			if(eIn_tri(i,nt0))
558			SET_E_NTH_TRI(i,0,nid_t0);
559			else
560			SET_E_NTH_TRI(i,0,nid_t1);
561			}
562
563			if(E_NTH_TRI(i,1)==id_t0 \|\| E_NTH_TRI(i,1)==id_t1)
564			{
565			if(eIn_tri(i,nt0))
566			SET_E_NTH_TRI(i,1,nid_t0);
567			else
568			SET_E_NTH_TRI(i,1,nid_t1);
569			}
570			}
571			id_t0 = nid_t0;
572			id_t1 = nid_t1;
573			e_new = eNew_edge();
574			SET_E_NTH_VERT(e_new,0,id_p);
575			SET_E_NTH_VERT(e_new,1,id_v2);
576			SET_E_NTH_TRI(e_new,0,id_t0);
577			SET_E_NTH_TRI(e_new,1,id_t1);
578			}
579			}
580	gwlarson	3.2	smUpdate_locator(sm,add,del);
581	gwlarson	3.1	}
582
583			int
584			smMesh_remove_vertex(sm,id)
585			SM *sm;
586			int id;
587			{
588			int tri;
589			LIST *elist;
590			int cnt,debug;
591			/* generate list of vertices that form the boundary of the
592			star polygon formed by vertex id and all of its adjacent
593			triangles
594			*/
595			eClear_edges();
596			elist = smVertex_star_polygon(sm,id);
597			if(!elist)
598			return(FALSE);
599
600			/* Triangulate spherical polygon */
601	gwlarson	3.3	smTriangulate(sm,elist);
602	gwlarson	3.1
603
604			/* Fix up new triangles to be Delaunay */
605	gwlarson	3.3	smFix_edges(sm);
606	gwlarson	3.1
607			return(TRUE);
608			}
609
610			/* Remove point from samples, and from mesh. Delete any triangles
611			adjacent to the point and re-triangulate the hole
612			Return TRUE is point found , FALSE otherwise
613			*/
614			int
615			smDelete_point(sm,id)
616			SM *sm;
617			int id;
618			{
619
620			/* Remove the corresponding vertex from the mesh */
621			smMesh_remove_vertex(sm,id);
622			/* Free the sample point */
623			smDelete_sample(sm,id);
624			return(TRUE);
625			}
626
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631
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633
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