feat: Added getVertexNeighbors() call to find neighboring edges/vertices

LBNL-ETA · Apr 23, 2021 · 624057e · 624057e
1 parent c6dd277
commit 624057e
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Showing 2 changed files with 58 additions and 4 deletions.
diff --git a/src/common/objutil.c b/src/common/objutil.c
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: objutil.c,v 2.18 2021/04/09 15:26:41 greg Exp $";
+static const char RCSid[] = "$Id: objutil.c,v 2.19 2021/04/23 18:31:45 greg Exp $";
 #endif
 /*
  *  Basic .OBJ scene handling routines.
@@ -700,6 +700,56 @@ addFace(Scene *sc, VNDX vid[], int nv)
 	return(f);
 }
 
+/* Get neighbor vertices: malloc array with valence in index[0] */
+int *
+getVertexNeighbors(Scene *sc, int vid)
+{
+	int	*varr;
+	Face	*f;
+	int	j=0;
+
+	if (sc == NULL || (vid < 0) | (vid >= sc->nverts) ||
+			(f = sc->vert[vid].vflist) == NULL)
+		return(NULL);
+
+	varr = (int *)emalloc(sizeof(int)*CHUNKSIZ);
+	varr[0] = 0;				/* add unique neighbors */
+	for ( ; f != NULL; f = f->v[j].fnext) {
+		int	i, cvi;
+		for (j = f->nv; j--; )		/* find ourself in poly */
+			if (f->v[j].vid == vid)
+				break;
+		if (j < 0)			/* this is an error */
+			break;
+		if (f->nv < 3)			/* also never happens */
+			continue;
+						/* check previous neighbor */
+		cvi = f->v[ (j > 0) ? j-1 : f->nv-1 ].vid;
+		for (i = varr[0]+1; --i; )	/* making sure not in list */
+			if (varr[i] == cvi)
+				break;
+		if (!i) {			/* new neighbor? */
+			varr = chunk_alloc(int, varr, varr[0]+1);
+			varr[++varr[0]] = cvi;
+		}
+						/* check next neighbor */
+		cvi = f->v[ (j < f->nv-1) ? j+1 : 0 ].vid;
+		for (i = varr[0]+1; --i; )
+			if (varr[i] == cvi)
+				break;
+		if (!i) {
+			varr = chunk_alloc(int, varr, varr[0]+1);
+			varr[++varr[0]] = cvi;
+		}
+	}
+	if (!varr[0]) {
+		efree((char *)varr);		/* something went awry */
+		return(NULL);
+	}
+						/* tighten array & return */
+	return((int *)erealloc((char *)varr, sizeof(int)*(varr[0]+1)));
+}
+
 /* Callback for growBoundingBox() */
 static int
 addBBox(Scene *sc, Face *f, void *p)

diff --git a/src/common/objutil.h b/src/common/objutil.h
@@ -1,4 +1,4 @@
-/* RCSid $Id: objutil.h,v 2.15 2021/04/09 15:26:41 greg Exp $ */
+/* RCSid $Id: objutil.h,v 2.16 2021/04/23 18:31:45 greg Exp $ */
 /*
  *  Declarations for .OBJ file utility
  *
@@ -181,6 +181,9 @@ extern void	setMaterial(Scene *sc, const char *nm);
 /* Add a new face to our scene, using current group and material */
 extern Face *	addFace(Scene *sc, VNDX vid[], int nv);
 
+/* Get neighbor vertices: malloc array with valence in index[0] */
+extern int *	getVertexNeighbors(Scene *sc, int vid);
+
 /* Expand bounding box min & max (initialize bbox to all zeroes) */
 extern int	growBoundingBox(Scene *sc, double bbox[2][3],
 					int flreq, int flexc);
@@ -208,10 +211,11 @@ extern void     efree(char *cp);
 #define getGroupID(sc,nm)	findName(nm, (const char **)(sc)->grpname, (sc)->ngrps)
 #define getMaterialID(sc,nm)	findName(nm, (const char **)(sc)->matname, (sc)->nmats)
 
-#define CHUNKSIZ	128	/* object allocation chunk size */
+#define CHUNKBITS	7		/* object allocation chunk bits */
+#define CHUNKSIZ	(1<<CHUNKBITS)	/* object allocation chunk size */
 
 #define chunk_alloc(typ, arr, nold) \
-		((nold)%CHUNKSIZ ? (arr) : \
+		((nold)&(CHUNKSIZ-1) ? (arr) : \
 		(typ *)erealloc((char *)(arr), sizeof(typ)*((nold)+CHUNKSIZ)))
 
 #ifdef __cplusplus