tclpathplan.c   [plain text]

/*
 * Tcl binding to drive Stephen North's and
 * Emden Gansner's shortest path code.
 *
 * ellson@graphviz.org   October 2nd, 1996
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

/* avoid compiler warnings with template changes in Tcl8.4 */
/*    specifically just the change to Tcl_CmdProc */
#define USE_NON_CONST

/* for sincos */
#define _GNU_SOURCE 1

#ifdef HAVE_AST
#include                <ast.h>
#include                <vmalloc.h>
#else
#include                <sys/types.h>
#include                <stdlib.h>
#include                <string.h>
#include                <unistd.h>
#endif

#include <assert.h>
#include <math.h>
#include <pathutil.h>
#include <vispath.h>
#include <tri.h>
#include <tcl.h>
#include "tclhandle.h"

#ifndef CONST84
#define CONST84
#endif

typedef Ppoint_t point;

typedef struct poly_s {
	int			id;
	Ppoly_t		boundary;
} poly;

typedef struct vgpane_s {
	int			Npoly;			/* number of polygons */
	poly		*poly;			/* set of polygons */
	int			N_poly_alloc;	/* for allocation */
	vconfig_t	*vc;			/* visibility graph handle */
	Tcl_Interp	*interp;		/* interpreter that owns the binding */
	char		*triangle_cmd;	/* why is this here any more */
} vgpane_t;

#ifndef HAVE_SINCOS
# define sincos(x,s,c) *s = sin(x); *c = cos(x)
#endif

tblHeader_pt vgpaneTable;

extern void make_CW(Ppoly_t *poly);
extern int Plegal_arrangement( Ppoly_t	**polys, int	n_polys);

static int polyid=0;   /* unique and unchanging id for each poly */

static poly *allocpoly(vgpane_t *vgp, int id, int npts)
{
	poly	*rv;
	if (vgp->Npoly >= vgp->N_poly_alloc) {
		vgp->N_poly_alloc *= 2;
		vgp->poly = realloc(vgp->poly,vgp->N_poly_alloc*sizeof(poly));
	}
	rv = &(vgp->poly[vgp->Npoly++]);
	rv->id = id;
	rv->boundary.pn = 0;
	rv->boundary.ps = malloc(npts * sizeof(point));
	return rv;
}

static void vc_stale(vgpane_t *vgp)
{
	if (vgp->vc) {
		Pobsclose(vgp->vc);
		vgp->vc = (vconfig_t*)0;
	}
}

static int vc_refresh(vgpane_t *vgp)
{
	int			i;
	Ppoly_t		**obs;

	if (vgp->vc == (vconfig_t*)0) {
		obs = malloc(vgp->Npoly * sizeof(Ppoly_t));
		for (i= 0; i < vgp->Npoly; i++)
			obs[i] = &(vgp->poly[i].boundary);
		if (NOT(Plegal_arrangement(obs,vgp->Npoly)))
			fprintf(stderr,"bad arrangement\n");
		else
			vgp->vc = Pobsopen(obs, vgp->Npoly);
		free(obs);
	}
	return (vgp->vc != 0);
}

static void
dgsprintxy(Tcl_DString *result, int npts, point p[])
{
    int i;
    char buf[20];
 
    if (npts != 1) Tcl_DStringStartSublist(result);
    for (i = 0; i < npts; i++) {
        sprintf(buf, "%g", p[i].x);
        Tcl_DStringAppendElement(result, buf);
        sprintf(buf, "%g", p[i].y);
        Tcl_DStringAppendElement(result, buf);
    }
    if (npts != 1) Tcl_DStringEndSublist(result);
}

static void
expandPercentsEval(
    Tcl_Interp * interp,     /* interpreter context */
    register char *before,   /* Command with percent expressions */
    char *r,		     /* vgpaneHandle string to substitute for "%r" */
    int npts,                /* number of coordinates */
    point *ppos              /* Cordinates to substitute for %t */
)
{
    register char  *string;
    Tcl_DString     scripts;
 
    Tcl_DStringInit(&scripts);
    while (1) {
        /*
         * Find everything up to the next % character and append it to the
         * result string.
         */
 
        for (string = before; (*string != 0) && (*string != '%'); string++) {
            /* Empty loop body. */
        }
        if (string != before) {
            Tcl_DStringAppend(&scripts, before, string - before);
            before = string;
        }
        if (*before == 0) {
            break;
        }
        /*
         * There's a percent sequence here.  Process it.
         */
 
        switch (before[1]) {
        case 'r':
            Tcl_DStringAppend(&scripts, r, strlen(r));  /* vgcanvasHandle */
	    break;
        case 't':
            dgsprintxy(&scripts, npts, ppos);
            break;
        default:
            Tcl_DStringAppend(&scripts, before+1, 1);
            break;
        }
        before += 2;
    }
    if (Tcl_GlobalEval(interp, Tcl_DStringValue(&scripts)) != TCL_OK)
        fprintf(stderr, "%s while in binding: %s\n\n",
                interp->result, Tcl_DStringValue(&scripts));
    Tcl_DStringFree(&scripts);
}

void
triangle_callback(void *vgparg, point pqr[])
{
    char		vbuf[20];
	vgpane_t	*vgp;

	vgp = vgparg;

/*	    TBL_ENTRY((tblHeader_pt)vgpaneTable, (ubyte_pt)vgp));*/

    if (vgp->triangle_cmd) {
        sprintf(vbuf, "vgpane%lu", 
	    (unsigned long) (((ubyte_pt)vgp - (vgpaneTable->bodyPtr)) / (vgpaneTable->entrySize)));
	expandPercentsEval(vgp->interp, vgp->triangle_cmd, vbuf, 3, pqr);
    }
}

static char *
buildBindings(char *s1, char *s2)
/*
 * previous binding in s1 binding to be added in s2 result in s3
 *
 * if s2 begins with + then append (separated by \n) else s2 replaces if
 * resultant string is null then bindings are deleted
 */
{
    char           *s3;
    int             l;
 
    if (s2[0] == '+') {
        if (s1) {
            l = strlen(s2) - 1;
            if (l) {
                s3 = malloc(strlen(s1) + l + 2);
                strcpy(s3, s1);
                strcat(s3, "\n");
                strcat(s3, s2 + 1);
                free(s1);
            } else {
                s3 = s1;
            }
        } else {
            l = strlen(s2) - 1;
            if (l) {
                s3 = malloc(l + 2);
                strcpy(s3, s2 + 1);
            } else {
                s3 = (char *) NULL;
            }
        }
    } else {
        if (s1)
            free(s1);
        l = strlen(s2);
        if (l) {
            s3 = malloc(l + 2);
            strcpy(s3, s2);
        } else {
            s3 = (char *) NULL;
        }
    }
    return s3;
}



/* convert x and y string args to point */
static int
scanpoint (Tcl_Interp *interp, char *argv[], point *p)
{
    if (sscanf(argv[0], "%lg", &(p->x)) != 1) {
        Tcl_AppendResult(interp, "invalid x coordinate: \"", argv[0],
            "\"", (char *)NULL);
        return TCL_ERROR;
    }
    if (sscanf(argv[1], "%lg", &(p->y)) != 1) {
        Tcl_AppendResult(interp, "invalid y coordinate: \"", argv[1],
            "\"", (char *)NULL);
        return TCL_ERROR;
    }
    return TCL_OK;
}

static point
center(point vertex[], int n)
{
    int i;
    point c;

    c.x = c.y = 0;
    for (i=0; i<n; i++) {
        c.x += vertex[i].x;
        c.y += vertex[i].y;
    }
    c.x /= n;
    c.y /= n;
    return c;
}

static double
distance(point p, point q)
{
    double dx, dy;

    dx = p.x - q.x;
    dy = p.y - q.y;
    return sqrt(dx*dx + dy*dy);
}

static point
rotate(point c, point p, double alpha)
{
    point q;
    double beta, r, sina, cosa;

    r = distance(c,p);
    beta = atan2(p.x - c.x, p.y - c.y);
    sincos(beta+alpha, &sina, &cosa);
    q.x = c.x +  r * sina;
    q.y = c.y -  r * cosa; /* adjust for tk y-down */
    return q;
}

static point
scale(point c, point p, double gain)
{
    point q;

    q.x = c.x + gain * (p.x - c.x);
    q.y = c.y + gain * (p.y - c.y);
    return q;
}

static int
remove_poly (vgpane_t *vgp, int polyid)
{
    int i, j;

    for (i=0; i < vgp->Npoly; i++) {
		if (vgp->poly[i].id == polyid) {
			free(vgp->poly[i].boundary.ps);
			for (j = i++; i < vgp->Npoly; i++, j++) {
				vgp->poly[j] = vgp->poly[i];
			}
			vgp->Npoly -= 1;
			vc_stale(vgp);
			return TRUE;
		}
    }
    return FALSE;
}

static int
insert_poly (Tcl_Interp *interp, vgpane_t *vgp, int polyid, char *vargv[], int vargc)
{
	poly	*np;
    int i, result;

	np = allocpoly(vgp, polyid, vargc);
    for (i=0; i < vargc; i += 2) {
        result = scanpoint(interp, &vargv[i], &(np->boundary.ps[np->boundary.pn]));
        if (result != TCL_OK) return result;
		np->boundary.pn++;
    }
    make_CW(&(np->boundary));
	vc_stale(vgp);
    return TCL_OK;
}

static void
make_barriers(vgpane_t *vgp, int pp, int qp, Pedge_t **barriers, int *n_barriers)
{
	int		i, j, k, n, b;
	Pedge_t	*bar;

	n = 0;
	for (i = 0; i < vgp->Npoly; i++) {
		if (vgp->poly[i].id == pp) continue;
		if (vgp->poly[i].id == qp) continue;
		n = n + vgp->poly[i].boundary.pn;
	}
	bar = malloc(n * sizeof(Pedge_t));
	b = 0;
	for (i = 0; i < vgp->Npoly; i++) {
		if (vgp->poly[i].id == pp) continue;
		if (vgp->poly[i].id == qp) continue;
		for (j = 0; j < vgp->poly[i].boundary.pn; j++) {
			k = j + 1;
			if (k >= vgp->poly[i].boundary.pn) k = 0;
			bar[b].a = vgp->poly[i].boundary.ps[j];
			bar[b].b = vgp->poly[i].boundary.ps[k];
			b++;
		}
	}
	assert(b == n);
	*barriers = bar;
	*n_barriers = n;
}

/* append the x and y coordinates of a point to the Tcl result */
static void
appendpoint (Tcl_Interp *interp, point p)
{
    char buf[30];

    sprintf(buf, "%g", p.x);
    Tcl_AppendElement(interp, buf);
    sprintf(buf, "%g", p.y);
    Tcl_AppendElement(interp, buf);
}

/* process vgpane methods */
static int
vgpanecmd(ClientData clientData, Tcl_Interp * interp, int argc, char *argv[])
{
    int              vargc, length, i, j, n, result;
    char             c, *s, **vargv, vbuf[30];
    vgpane_t 	     *vgp, **vgpp;
    point            p, q, *ps;
    poly            *tpp;
    double           alpha, gain;
	Pvector_t		slopes[2];
	Ppolyline_t		line, spline;
	int				pp, qp;		/* polygon indices for p, q */
	Pedge_t			*barriers;
	int				n_barriers;

    if (argc < 2) {
        Tcl_AppendResult(interp, "wrong # args: should be \"",
             " ", argv[0], " method ?arg arg ...?\"", (char *) NULL);
        return TCL_ERROR;
    }
    if (!(vgpp = (vgpane_t **)tclhandleXlate(vgpaneTable, argv[0]))) {
        Tcl_AppendResult(interp, "Invalid handle: \"", argv[0],
                "\"", (char *) NULL);
        return TCL_ERROR;
    }
	vgp = *vgpp;

    c = argv[1][0];
    length = strlen(argv[1]);

    if ((c == 'c') && (strncmp(argv[1], "coords", length) == 0)) {
        if ((argc < 3)) {
	    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
	        " ", argv[1], " id ?x1 y1 x2 y2...?\"", (char *) NULL);
	    return TCL_ERROR;
        }
        if (sscanf(argv[2], "%d", &polyid) != 1) {
			Tcl_AppendResult(interp, "not an integer: ", argv[2],
				(char *) NULL);
			return TCL_ERROR;
        }
		if (argc == 3) {
			/* find poly and return its coordinates */
			for (i=0; i < vgp->Npoly; i++) {
				if (vgp->poly[i].id == polyid) {
					n = vgp->poly[i].boundary.pn;
					for (j = 0; j < n; j++) {
						appendpoint(interp, vgp->poly[i].boundary.ps[j]);
					}
					return TCL_OK;
				}
			}
			Tcl_AppendResult(interp, " no such polygon: ", argv[2],
				(char *) NULL);
			return TCL_ERROR;
		}
		/* accept either inline or delimited list */
		if ((argc == 4)) {
			result = Tcl_SplitList(interp, argv[3], &vargc, (CONST84 char ***) &vargv);
			if (result != TCL_OK) {return result;}
		} else {
			vargc = argc-3;
			vargv = &argv[3];
		}
		if (!vargc || vargc%2) {
			Tcl_AppendResult(interp, 
				"There must be a multiple of two terms in the list.",
				(char *) NULL);
			return TCL_ERROR;
		}

		/* remove old poly, add modified polygon to the end with 
		   the same id as the original */

		if (! (remove_poly(vgp, polyid))) {
			Tcl_AppendResult(interp, " no such polygon: ", argv[2],
				(char *) NULL);
			return TCL_ERROR;
		}

        return (insert_poly(interp, vgp, polyid, vargv, vargc));

    } else if ((c == 'd') && (strncmp(argv[1], "debug", length) == 0)) {
		/* debug only */
		printf("debug output goes here\n");
		return TCL_OK;

    } else if ((c == 'd') && (strncmp(argv[1], "delete", length) == 0)) {
		/* delete a vgpane and all memory associated with it */
		if (vgp->vc) Pobsclose(vgp->vc);
		free(vgp->poly);	/* ### */
		Tcl_DeleteCommand(interp, argv[0]);
		free((char *)tclhandleFree(vgpaneTable, argv[0]));
        return TCL_OK;

    } else if ((c == 'f') && (strncmp(argv[1], "find", length) == 0)) {
		/* find the polygon that the point is inside and return it
		   id, or null */
		if ((argc < 3)) {
			Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
				" ", argv[1], " x y\"", (char *) NULL);
			return TCL_ERROR;
        }
		if (argc == 3) {
			result = Tcl_SplitList(interp, argv[2], &vargc, (CONST84 char ***) &vargv);
			if (result != TCL_OK) {return result;}
		} else {
			vargc = argc-2;
			vargv = &argv[2];
		}
		result = scanpoint(interp, &vargv[0], &p);
		if (result != TCL_OK) return result;

		/* determine the polygons (if any) that contain the point */
		for (i = 0; i < vgp->Npoly; i++) {
			if (in_poly(vgp->poly[i].boundary, p)) {
				sprintf(vbuf, "%d", vgp->poly[i].id);
				Tcl_AppendElement(interp, vbuf);
			}
		}
		return TCL_OK;

	} else if ((c == 'i') && (strncmp(argv[1], "insert", length) == 0)) {
		/* add poly to end poly list, and it coordinates to the end of 
		   the point list */
		if ((argc < 3)) {
			Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
				" ", argv[1], " x1 y1 x2 y2 ...\"", (char *) NULL);
			return TCL_ERROR;
		}
		/* accept either inline or delimited list */
		if ((argc == 3)) {
			result = Tcl_SplitList(interp, argv[2], &vargc, (CONST84 char ***) &vargv);
			if (result != TCL_OK) {return result;}
		} else {
			vargc = argc-2;
			vargv = &argv[2];
		}

		if (!vargc || vargc%2) {
			Tcl_AppendResult(interp, 
				"There must be a multiple of two terms in the list.",
				(char *) NULL);
			return TCL_ERROR;
		}

		polyid++;

		result = insert_poly(interp, vgp, polyid, vargv, vargc);
		if (result != TCL_OK) return result;

		sprintf(vbuf, "%d", polyid);
		Tcl_AppendResult(interp, vbuf, (char *) NULL);
		return TCL_OK;

	} else if ((c == 'l') && (strncmp(argv[1], "list", length) == 0)) {
		/* return list of polygon ids */
		for (i = 0; i < vgp->Npoly; i++) {
			sprintf(vbuf, "%d", vgp->poly[i].id);
			Tcl_AppendElement(interp, vbuf);
		}
		return TCL_OK;

	} else if ((c == 'p') && (strncmp(argv[1], "path", length) == 0)) {
		/* return a list of points corresponding to the shortest path
		   that does not cross the remaining "visible" polygons. */
        if ((argc < 3)) {
			Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
				" ", argv[1], " x1 y1 x2 y2\"", (char *) NULL);
			return TCL_ERROR;
        }
		if (argc == 3) {
            result = Tcl_SplitList(interp, argv[2], &vargc, (CONST84 char ***) &vargv);
            if (result != TCL_OK) {return result;}
		} else {
			vargc = argc-2;
			vargv = &argv[2];
        }
        if ((vargc < 4)) {
			Tcl_AppendResult(interp,
				"invalid points: should be: \"x1 y1 x2 y2\"",
				(char *) NULL);
			return TCL_ERROR;
        }
		result = scanpoint(interp, &vargv[0], &p);
		if (result != TCL_OK) return result;
		result = scanpoint(interp, &vargv[2], &q);
		if (result != TCL_OK) return result;

		/* only recompute the visibility graph if we have to */
		if ((vc_refresh(vgp))) {
			Pobspath(vgp->vc, p, POLYID_UNKNOWN, q, POLYID_UNKNOWN, &line);

			for (i = 0; i < line.pn; i++) {
				appendpoint(interp, line.ps[i]);
			}
		}
		
		return TCL_OK;

   } else if ((c == 'b') && (strncmp(argv[1], "bind", length) == 0)) {
        if ((argc < 2) || (argc > 4)) {
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                 argv[0], " bind triangle ?command?\"", (char *) NULL);
            return TCL_ERROR;
        }
        if (argc == 2) {
            Tcl_AppendElement(interp, "triangle");
            return TCL_OK;
        }
        length = strlen(argv[2]);
        if (strncmp(argv[2], "triangle", length) == 0) {
            s = vgp->triangle_cmd;
            if (argc == 4) vgp->triangle_cmd = s = buildBindings(s, argv[3]) ;
        } else {
            Tcl_AppendResult(interp, "unknown event \"", argv[2],
                 "\": must be one of:\n\ttriangle.", (char *) NULL);
            return TCL_ERROR;
        }
        if (argc == 3) Tcl_AppendResult(interp, s, (char *) NULL);
        return TCL_OK;

   } else if ((c == 'b') && (strncmp(argv[1], "bpath", length) == 0)) {
	/* return a list of points corresponding to the shortest path
	   that does not cross the remaining "visible" polygons. */
        if ((argc < 3)) {
			Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
				" ", argv[1], " x1 y1 x2 y2\"", (char *) NULL);
			return TCL_ERROR;
        }
		if (argc == 3) {
            result = Tcl_SplitList(interp, argv[2], &vargc, (CONST84 char ***) &vargv);
            if (result != TCL_OK) {return result;}
		} else {
			vargc = argc-2;
			vargv = &argv[2];
        }
        if ((vargc < 4)) {
			Tcl_AppendResult(interp,
				"invalid points: should be: \"x1 y1 x2 y2\"",
				(char *) NULL);
			return TCL_ERROR;
        }

		result = scanpoint(interp, &vargv[0], &p);
		if (result != TCL_OK) return result;
		result = scanpoint(interp, &vargv[2], &q);
		if (result != TCL_OK) return result;

		/* determine the polygons (if any) that contain the endpoints */
		pp = qp = POLYID_NONE;
		for (i = 0; i < vgp->Npoly; i++) {
			tpp = &(vgp->poly[i]);
			if ((pp == POLYID_NONE) && in_poly(tpp->boundary, p)) pp = i;
			if ((qp == POLYID_NONE) && in_poly(tpp->boundary, q)) qp = i;
		}
        
		if (vc_refresh(vgp)) {
			/*Pobspath(vgp->vc, p, pp, q, qp, &line);*/
			Pobspath(vgp->vc, p, POLYID_UNKNOWN, q, POLYID_UNKNOWN, &line);
			make_barriers(vgp, pp, qp, &barriers, &n_barriers);
			slopes[0].x = slopes[0].y = 0.0;
			slopes[1].x = slopes[1].y = 0.0;
			Proutespline (barriers, n_barriers, line, slopes, &spline);

			for (i = 0; i < spline.pn; i++) {
				appendpoint(interp, spline.ps[i]);
			}
		}
		return TCL_OK;

    } else if ((c == 'b') && (strncmp(argv[1], "bbox", length) == 0)) {
        if ((argc < 3)) {
			Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
				" ", argv[1], " id\"", (char *) NULL);
			return TCL_ERROR;
		}
		if (sscanf(argv[2], "%d", &polyid) != 1) {
			Tcl_AppendResult(interp, "not an integer: ", argv[2],
				(char *) NULL);
			return TCL_ERROR;
		}
		for (i=0; i < vgp->Npoly; i++) {
			if (vgp->poly[i].id == polyid) {
				Ppoly_t	pp = vgp->poly[i].boundary;
				point	LL, UR;
				LL = UR = pp.ps[0];
				for (j = 1; j < pp.pn; j++) {
					p = pp.ps[j];
					if (p.x > UR.x) UR.x = p.x;
					if (p.y > UR.y) UR.y = p.y;
					if (p.x < LL.x) LL.x = p.x;
					if (p.y < LL.y) LL.y = p.y;
				}
				appendpoint(interp, LL);
				appendpoint(interp, UR);
				return TCL_OK;
			}
		}
		Tcl_AppendResult(interp, " no such polygon: ", argv[2],
			(char *) NULL);
		return TCL_ERROR;

    } else if ((c == 'c') && (strncmp(argv[1], "center", length) == 0)) {
        if ((argc < 3)) {
			Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
				" ", argv[1], " id\"", (char *) NULL);
			return TCL_ERROR;
        }
        if (sscanf(argv[2], "%d", &polyid) != 1) {
			Tcl_AppendResult(interp, "not an integer: ", argv[2],
				(char *) NULL);
			return TCL_ERROR;
        }
		for (i=0; i < vgp->Npoly; i++) {
			if (vgp->poly[i].id == polyid) {
				appendpoint(interp, center(vgp->poly[i].boundary.ps,
					vgp->poly[i].boundary.pn));
				return TCL_OK;
			}
        }
        Tcl_AppendResult(interp, " no such polygon: ", argv[2],
			(char *) NULL);
        return TCL_ERROR;

	} else if ((c == 't') && (strncmp(argv[1], "triangulate", length) == 0)) {
        if ((argc < 2)) {
			Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
				" id ", (char *) NULL);
			return TCL_ERROR;
        }

        if (sscanf(argv[2], "%d", &polyid) != 1) {
			Tcl_AppendResult(interp, "not an integer: ", argv[2],
				(char *) NULL);
			return TCL_ERROR;
        }

		for (i=0; i < vgp->Npoly; i++) {
			if (vgp->poly[i].id == polyid) {
				Ptriangulate(&(vgp->poly[i].boundary),triangle_callback,vgp);
				return TCL_OK;
			}
		}
		Tcl_AppendResult(interp, " no such polygon: ", argv[2], (char *) NULL);
        return TCL_ERROR;
    } else if ((c == 'r') && (strncmp(argv[1], "rotate", length) == 0)) {
        if ((argc < 4)) {
			Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
				" ", argv[1], " id alpha\"", (char *) NULL);
			return TCL_ERROR;
        }
        if (sscanf(argv[2], "%d", &polyid) != 1) {
			Tcl_AppendResult(interp, "not an integer: ", argv[2],
				(char *) NULL);
			return TCL_ERROR;
        }
        if (sscanf(argv[3], "%lg", &alpha) != 1) {
			Tcl_AppendResult(interp, "not an angle in radians: ", argv[3],
				(char *) NULL);
			return TCL_ERROR;
        }
		for (i=0; i < vgp->Npoly; i++) {
			if (vgp->poly[i].id == polyid) {
				n = vgp->poly[i].boundary.pn;
				ps = vgp->poly[i].boundary.ps;
				p = center(ps, n);
				for (j = 0; j < n; j++) {
					appendpoint(interp, rotate(p, ps[j], alpha));
				}
				return TCL_OK;
			}
        }
        Tcl_AppendResult(interp, " no such polygon: ", argv[2],
	    (char *) NULL);
        return TCL_ERROR;

    } else if ((c == 's') && (strncmp(argv[1], "scale", length) == 0)) {
        if ((argc < 4)) {
			Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
				" ", argv[1], " id gain\"", (char *) NULL);
			return TCL_ERROR;
        }
        if (sscanf(argv[2], "%d", &polyid) != 1) {
			Tcl_AppendResult(interp, "not an integer: ", argv[2],
				(char *) NULL);
			return TCL_ERROR;
        }
        if (sscanf(argv[3], "%lg", &gain) != 1) {
			Tcl_AppendResult(interp, "not a number: ", argv[3],
				(char *) NULL);
			return TCL_ERROR;
        }
		for (i=0; i < vgp->Npoly; i++) {
			if (vgp->poly[i].id == polyid) {
				n = vgp->poly[i].boundary.pn;
				ps = vgp->poly[i].boundary.ps;
				for (j = 0; j < n; j++) {
					appendpoint(interp, scale(p, ps[j], gain));
				}
				return TCL_OK;
			}
        }
        Tcl_AppendResult(interp, " no such polygon: ", argv[2],
			(char *) NULL);
        return TCL_ERROR;

    } else if ((c == 'r') && (strncmp(argv[1], "remove", length) == 0)) {
        if ((argc < 3)) {
			Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
				" ", argv[1], " id\"", (char *) NULL);
			return TCL_ERROR;
        }
        if (sscanf(argv[2], "%d", &polyid) != 1) {
			Tcl_AppendResult(interp, "not an integer: ", argv[2],
				(char *) NULL);
			return TCL_ERROR;
        }

		if (remove_poly(vgp, polyid))
			return TCL_OK;

        Tcl_AppendResult(interp, " no such polygon: ", argv[2],
	        (char *) NULL);
        return TCL_ERROR;
    }

    Tcl_AppendResult(interp, "bad method \"", argv[1], "\" must be one of:",
        "\n\tbbox, bind, bpath, center, coords, delete, find,",
	"\n\tinsert, list, path, remove, rotate, scale, triangulate.", (char *) NULL);
    return TCL_ERROR;
}

static int
vgpane(ClientData clientData, Tcl_Interp * interp, int argc, char *argv[])
{
    char	vbuf[30];
    vgpane_t	*vgp;

	vgp = (vgpane_t *)malloc(sizeof(vgpane_t));
    *(vgpane_t **)tclhandleAlloc(vgpaneTable, vbuf, NULL) = vgp; 

	vgp->vc = (vconfig_t*)0;
    vgp->Npoly = 0;
    vgp->N_poly_alloc = 250;
    vgp->poly = malloc(vgp->N_poly_alloc * sizeof(poly));
    vgp->interp = interp;
    vgp->triangle_cmd = (char *) NULL;

    Tcl_CreateCommand(interp, vbuf, vgpanecmd,
	(ClientData) NULL, (Tcl_CmdDeleteProc *) NULL);
    Tcl_AppendResult(interp, vbuf, (char *) NULL);
    return TCL_OK;
}

int Tclpathplan_Init(Tcl_Interp * interp)
{
#ifdef USE_TCL_STUBS
	if (Tcl_InitStubs(interp, TCL_VERSION, 0) == NULL) {
		return TCL_ERROR;
	}
#else
    if (Tcl_PkgRequire(interp, "Tcl", TCL_VERSION, 0) == NULL) {
		return TCL_ERROR;
    }
#endif
    if (Tcl_PkgProvide(interp, "Tclpathplan", VERSION) != TCL_OK) {
		return TCL_ERROR;
    }

    Tcl_CreateCommand(interp, "vgpane", vgpane,
	(ClientData) NULL, (Tcl_CmdDeleteProc *) NULL);

    vgpaneTable = tclhandleInit("vgpane", sizeof(vgpane_t), 10);

    return TCL_OK;
}

int Tclpathplan_SafeInit(Tcl_Interp * interp)
{
    return Tclpathplan_Init(interp);
}