File: plot3d.c

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#ifndef lint
static char    *RCSid = "$Id: plot3d.c,v 1.36 1998/06/18 14:55:14 ddenholm Exp $";
#endif

/* GNUPLOT - plot3d.c */

/*[
 * Copyright 1986 - 1993, 1998   Thomas Williams, Colin Kelley
 *
 * Permission to use, copy, and distribute this software and its
 * documentation for any purpose with or without fee is hereby granted,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.
 *
 * Permission to modify the software is granted, but not the right to
 * distribute the complete modified source code.  Modifications are to
 * be distributed as patches to the released version.  Permission to
 * distribute binaries produced by compiling modified sources is granted,
 * provided you
 *   1. distribute the corresponding source modifications from the
 *    released version in the form of a patch file along with the binaries,
 *   2. add special version identification to distinguish your version
 *    in addition to the base release version number,
 *   3. provide your name and address as the primary contact for the
 *    support of your modified version, and
 *   4. retain our contact information in regard to use of the base
 *    software.
 * Permission to distribute the released version of the source code along
 * with corresponding source modifications in the form of a patch file is
 * granted with same provisions 2 through 4 for binary distributions.
 *
 * This software is provided "as is" without express or implied warranty
 * to the extent permitted by applicable law.
]*/

#include "plot.h"
#include "setshow.h"
#include "binary.h"

#ifndef _Windows
#include "help.h"
#else
#define MAXSTR 255
#endif

#if defined(ATARI) || defined(MTOS)
#ifdef __PUREC__
#include <ext.h>
#include <tos.h>
#include <aes.h>
#else
#include <osbind.h>
#include <aesbind.h>
#endif /* __PUREC__ */
#endif /* ATARI || MTOS */

#ifndef STDOUT
#define STDOUT 1
#endif


#define inrange(z,min,max) ((min<max) ? ((z>=min)&&(z<=max)) : ((z>=max)&&(z<=min)) )


/* static prototypes */

static void get_3ddata __PROTO((struct surface_points *this_plot));
static void print_3dtable __PROTO((int pcount));
static void eval_3dplots __PROTO((void));
static void grid_nongrid_data __PROTO((struct surface_points *this_plot));
static void parametric_3dfixup __PROTO((struct surface_points *start_plot, int *plot_num));

/* the curves/surfaces of the plot */
struct surface_points *first_3dplot = NULL;
static struct udft_entry plot_func;


extern struct udft_entry *dummy_func;
extern int datatype[];
extern char timefmt[];
extern TBOOLEAN         is_3d_plot;
extern int plot_token;

/* in order to support multiple axes, and to
 * simplify ranging in parametric plots, we use
 * arrays to store some things. For 2d plots,
 * elements are  y1=0 x1=1 y2=2 x2=3
 * for 3d,  z=0, x=1, y=2
 * these are given symbolic names in plot.h
 */

extern double          min_array[AXIS_ARRAY_SIZE], max_array[AXIS_ARRAY_SIZE];
extern int             auto_array[AXIS_ARRAY_SIZE];
extern TBOOLEAN        log_array[AXIS_ARRAY_SIZE];
extern double          base_array[AXIS_ARRAY_SIZE];
extern double          log_base_array[AXIS_ARRAY_SIZE];

/* some file-wide variables to store which axis we are using */
static int x_axis, y_axis, z_axis;


/* info from datafile module */
extern int df_datum;
extern int df_line_number;
extern int df_no_use_specs;
extern int df_eof;
extern int df_timecol[];
extern TBOOLEAN df_matrix;

#define Inc_c_token if (++c_token >= num_tokens)	\
                        int_error ("Syntax error", c_token);

extern int reverse_range[];

/*
 * IMHO, code is getting too cluttered with repeated chunks of
 * code. Some macros to simplify, I hope.
 *
 * do { } while(0) is comp.lang.c recommendation for complex macros
 * also means that break can be specified as an action, and it will
 * 
 */

/*  copy scalar data to arrays
 * optimiser should optimise infinite away
 * dont know we have to support ranges [10:-10] - lets reverse
 * it for now, then fix it at the end.
 */
#define INIT_ARRAYS(axis, min, max, auto, is_log, base, log_base, infinite) \
do{if ((auto_array[axis]=auto)==0 && max<min) {\
	min_array[axis]=max;\
   max_array[axis]=min; /* we will fix later */ \
 } else { \
	min_array[axis]=(infinite && (auto&1)) ? VERYLARGE : min; \
	max_array[axis]=(infinite && (auto&2)) ? -VERYLARGE : max; \
 } \
 log_array[axis]=is_log; base_array[axis]=base; log_base_array[axis]=log_base;\
}while(0)
 
/* handle reversed ranges */
#define CHECK_REVERSE(axis) \
do{\
 if (auto_array[axis]==0 && max_array[axis] < min_array[axis]) {\
  double temp=min_array[axis]; min_array[axis]=max_array[axis]; max_array[axis]=temp;\
  reverse_range[axis]=1; \
 } else reverse_range[axis] = (range_flags[axis]&RANGE_REVERSE); \
}while(0)


/* get optional [min:max] */
#define LOAD_RANGE(axis) \
do {\
 if (equals(c_token, "[")) { \
  c_token++; \
  auto_array[axis] = load_range(axis,&min_array[axis], &max_array[axis], auto_array[axis]);\
  if (!equals(c_token, "]"))\
   int_error("']' expected", c_token);\
  c_token++;\
 }\
} while (0)

 
/* store VALUE or log(VALUE) in STORE, set TYPE as appropriate
 * Do OUT_ACTION or UNDEF_ACTION as appropriate
 * adjust range provided type is INRANGE (ie dont adjust y if x is outrange
 * VALUE must not be same as STORE
 */

#define STORE_WITH_LOG_AND_FIXUP_RANGE(STORE, VALUE, TYPE, AXIS, OUT_ACTION, UNDEF_ACTION)\
do { if (log_array[AXIS]) { if (VALUE<0.0) {TYPE=UNDEFINED; UNDEF_ACTION; break;} \
              else if (VALUE==0.0){STORE=-VERYLARGE; TYPE=OUTRANGE; OUT_ACTION; break;} \
              else { STORE=log(VALUE)/log_base_array[AXIS]; } \
     } else STORE=VALUE; \
     if (TYPE != INRANGE) break;  /* dont set y range if x is outrange, for example */ \
     if ( VALUE<min_array[AXIS] ) \
      if (auto_array[AXIS] & 1) min_array[AXIS]=VALUE; else { TYPE=OUTRANGE; OUT_ACTION; break; }  \
     if ( VALUE>max_array[AXIS] ) \
     if (auto_array[AXIS] & 2) max_array[AXIS]=VALUE; else { TYPE=OUTRANGE; OUT_ACTION; }   \
} while(0)
     
/* use this instead empty macro arguments to work around NeXT cpp bug */
/* if this fails on any system, we might use ((void)0) */
#define NOOP /* */

/* check axis range is not too small -
 * extend if you can (autoscale), else report error
 */
#ifdef HAVE_CPP_STRINGIFY
# define STRINGIFY(x) #x
# define RANGE_MSG(x) #x " range is less than threshold : see `set zero`"
#else
# define STRINGIFY(x) "x"
# define RANGE_MSG(x) "x range is less than threshold : see `set zero`"
#endif

#define FIXUP_RANGE(AXIS, WHICH) \
do{if (fabs(max_array[AXIS] - min_array[AXIS]) < zero)    \
    if (auto_array[AXIS]) { /* widen range */  \
     fprintf(stderr, "Warning: empty %s range [%g:%g], ", STRINGIFY(WHICH), min_array[AXIS], max_array[AXIS]);      \
     if (fabs(min_array[AXIS]) < zero) { \
      if (auto_array[AXIS] & 1) min_array[AXIS] = -1.0; \
      if (auto_array[AXIS] & 2) max_array[AXIS] = 1.0;   \
     } else if (max_array[AXIS] < 0) { \
      if (auto_array[AXIS] & 1) min_array[AXIS] *= 1.1; if (auto_array[AXIS] & 2) max_array[AXIS] *= 0.9;    \
     } else { if (auto_array[AXIS] & 1) min_array[AXIS] *= 0.9; if (auto_array[AXIS] & 2) max_array[AXIS] *= 1.1;  }  \
     fprintf(stderr, "adjusting to [%g:%g]\n", min_array[AXIS], max_array[AXIS]);          \
    } else int_error(RANGE_MSG(WHICH), c_token);   \
}while(0)

/* check range and take logs of min and max if logscale
 * this also restores min and max for ranges like [10:-10]
 */

#define FIXUP_RANGE_FOR_LOG(AXIS, WHICH) \
do { if (reverse_range[AXIS]) { \
      double temp = min_array[AXIS]; \
      min_array[AXIS]=max_array[AXIS]; \
      max_array[AXIS]=temp; \
     }\
     if (log_array[AXIS]) { \
      if (min_array[AXIS]<=0.0 || max_array[AXIS]<=0.0) \
       int_error(RANGE_MSG(WHICH), NO_CARET); \
      min_array[AXIS] = log(min_array[AXIS])/log_base_array[AXIS]; \
      max_array[AXIS] = log(max_array[AXIS])/log_base_array[AXIS];  \
} } while(0)



/* support for dynamic size of input line */

void plot3drequest()
/*
 * in the parametric case we would say splot [u= -Pi:Pi] [v= 0:2*Pi] [-1:1]
 * [-1:1] [-1:1] sin(v)*cos(u),sin(v)*cos(u),sin(u) in the non-parametric
 * case we would say only splot [x= -2:2] [y= -5:5] sin(x)*cos(y)
 * 
 */
{
    TBOOLEAN         changed;
    int             dummy_token0 = -1, dummy_token1 = -1;

    is_3d_plot = TRUE;

    if (parametric && strcmp(dummy_var[0], "t") == 0) {
	strcpy(dummy_var[0], "u");
	strcpy(dummy_var[1], "v");
    }
    autoscale_lx = autoscale_x;
    autoscale_ly = autoscale_y;
    autoscale_lz = autoscale_z;

    if (!term)			/* unknown */
	int_error("use 'set term' to set terminal type first", c_token);

    if (equals(c_token, "[")) {
	c_token++;
	if (isletter(c_token)) {
	    if (equals(c_token + 1, "=")) {
		dummy_token0 = c_token;
		c_token += 2;
	    } else {
		/* oops; probably an expression with a variable. */
		/* Parse it as an xmin expression. */
		/* used to be: int_error("'=' expected",c_token); */
	    }
	}
	changed = parametric ? load_range(U_AXIS,&umin, &umax, autoscale_lu) : load_range(FIRST_X_AXIS,&xmin, &xmax, autoscale_lx);
	if (!equals(c_token, "]"))
	    int_error("']' expected", c_token);
	c_token++;
	/* if (changed) */
		if(parametric) 
			/* autoscale_lu = FALSE; */
			autoscale_lu = changed;
		else
			/* autoscale_lx = FALSE; */
			autoscale_lx = changed;
    }
    if (equals(c_token, "[")) {
	c_token++;
	if (isletter(c_token)) {
	    if (equals(c_token + 1, "=")) {
		dummy_token1 = c_token;
		c_token += 2;
	    } else {
		/* oops; probably an expression with a variable. */
		/* Parse it as an xmin expression. */
		/* used to be: int_error("'=' expected",c_token); */
	    }
	}
	changed = parametric ? load_range(V_AXIS,&vmin, &vmax, autoscale_lv) : load_range(FIRST_Y_AXIS,&ymin, &ymax, autoscale_ly);
	if (!equals(c_token, "]"))
	    int_error("']' expected", c_token);
	c_token++;
	/* if (changed) */
		if(parametric) 
			/* autoscale_lv = FALSE; */
			autoscale_lv = changed;
		else
			/* autoscale_ly = FALSE; */
			autoscale_ly = changed;
    }

    if (parametric) {
    if (equals(c_token, "[")) {	/* set optional x (parametric) or z ranges */
	c_token++;
	autoscale_lx = load_range(FIRST_X_AXIS,&xmin, &xmax, autoscale_lx);
	if (!equals(c_token, "]"))
	    int_error("']' expected", c_token);
	c_token++;
    }
    if (equals(c_token, "[")) {	/* set optional y ranges */
	c_token++;
	autoscale_ly = load_range(FIRST_Y_AXIS,&ymin, &ymax, autoscale_ly);
	if (!equals(c_token, "]"))
	    int_error("']' expected", c_token);
	c_token++;
    }
	 } /* parametric */
	 
    if (equals(c_token, "[")) {	/* set optional z ranges */
	c_token++;
	autoscale_lz = load_range(FIRST_Z_AXIS,&zmin, &zmax, autoscale_lz);
	if (!equals(c_token, "]"))
	    int_error("']' expected", c_token);
	c_token++;
    }

    CHECK_REVERSE(FIRST_X_AXIS);
    CHECK_REVERSE(FIRST_Y_AXIS);
    CHECK_REVERSE(FIRST_Z_AXIS);

    /* use the default dummy variable unless changed */
    if (dummy_token0 >= 0)
	copy_str(c_dummy_var[0], dummy_token0, MAX_ID_LEN);
    else
	(void) strcpy(c_dummy_var[0], dummy_var[0]);

    if (dummy_token1 >= 0)
	copy_str(c_dummy_var[1], dummy_token1, MAX_ID_LEN);
    else
	(void) strcpy(c_dummy_var[1], dummy_var[1]);

    eval_3dplots();
}


static void grid_nongrid_data(this_plot)
struct surface_points *this_plot;
{
    int i, j, k;
    double x, y, z, w, dx, dy, xmin, xmax, ymin, ymax;
    struct iso_curve *old_iso_crvs = this_plot->iso_crvs;
    struct iso_curve *icrv, *oicrv, *oicrvs;

    /* Compute XY bounding box on the original data. */
    xmin = xmax = old_iso_crvs->points[0].x;
    ymin = ymax = old_iso_crvs->points[0].y;
    for (icrv = old_iso_crvs; icrv != NULL; icrv = icrv->next) {
	struct coordinate GPHUGE *points = icrv->points;

	for (i = 0; i < icrv->p_count; i++, points++) {
	    if (xmin > points->x)
		xmin = points->x;
	    if (xmax < points->x)
		xmax = points->x;
	    if (ymin > points->y)
		ymin = points->y;
	    if (ymax < points->y)
		ymax = points->y;
	}
    }

    dx = (xmax - xmin) / (dgrid3d_col_fineness - 1);
    dy = (ymax - ymin) / (dgrid3d_row_fineness - 1);

    /* Create the new grid structure, and compute the low pass filtering from
     * non grid to grid structure.
     */
    this_plot->iso_crvs = NULL;
    this_plot->num_iso_read = dgrid3d_col_fineness;
    this_plot->has_grid_topology = TRUE;
    for (i = 0, x = xmin; i < dgrid3d_col_fineness; i++, x += dx) {
	struct coordinate GPHUGE *points;

	icrv = iso_alloc(dgrid3d_row_fineness + 1);
	icrv->p_count = dgrid3d_row_fineness;
	icrv->next = this_plot->iso_crvs;
	this_plot->iso_crvs = icrv;
	points = icrv->points;

	for (j = 0, y = ymin; j < dgrid3d_row_fineness; j++, y += dy, points++) {
	    z = w = 0.0;

	    for (oicrv = old_iso_crvs; oicrv != NULL; oicrv = oicrv->next) {
		struct coordinate GPHUGE *opoints = oicrv->points;
		for (k = 0; k < oicrv->p_count; k++, opoints++) {
		    double dist,
			   dist_x = fabs( opoints->x - x ),
			   dist_y = fabs( opoints->y - y );

		    switch (dgrid3d_norm_value) {
			case 1:
			    dist = dist_x + dist_y;
			    break;
			case 2:
			    dist = dist_x * dist_x + dist_y * dist_y;
			    break;
			case 4:
			    dist = dist_x * dist_x + dist_y * dist_y;
			    dist *= dist;
			    break;
			case 8:
			    dist = dist_x * dist_x + dist_y * dist_y;
			    dist *= dist;
			    dist *= dist;
			    break;
			case 16:
			    dist = dist_x * dist_x + dist_y * dist_y;
			    dist *= dist;
			    dist *= dist;
			    dist *= dist;
			    break;
			default:
                            dist = pow( dist_x, (double)dgrid3d_norm_value ) +
                                   pow( dist_y, (double)dgrid3d_norm_value );
			    break;
		    }

		    /* The weight of this point is inverse proportional
		     * to the distance.
		     */
		    if ( dist == 0.0 )
#if !defined(AMIGA_SC_6_1) && !defined(__PUREC__)
			dist = VERYLARGE;
#else /* !AMIGA_SC_6_1 && !__PUREC__ */
			/* Multiplying VERYLARGE by opoints->z below
			 * might yield Inf (i.e. a number that can't
			 * be represented on the machine). This will
			 * result in points->z being set to NaN. It's
			 * better to have a pretty large number that is
			 * also on the safe side... The numbers that are
			 * read by gnuplot are float values anyway, so
			 * they can't be bigger than FLT_MAX. So setting
			 * dist to FLT_MAX^2 will make dist pretty large
			 * with respect to any value that has been read. */
			dist = ((double)FLT_MAX)*((double)FLT_MAX);
#endif /* !AMIGA_SC_6_1 && !__PUREC__ */
		    else
			dist = 1.0 / dist;

		    z += opoints->z * dist;
		    w += dist;
		}
	    }

	    points->x = x;
	    points->y = y;
	    points->z = z / w;
	    points->type = INRANGE;
	}
    }
	
    /* Delete the old non grid data. */
    for (oicrvs = old_iso_crvs; oicrvs != NULL;) {
	oicrv = oicrvs;
	oicrvs = oicrvs->next;
	iso_free(oicrv);
    }
}

static void get_3ddata(this_plot)
    struct surface_points *this_plot;
/* this_plot->token is end of datafile spec, before title etc
 * will be moved passed title etc after we return
 */
{
	int xdatum=0;
	int ydatum=0;
	int i,j;
	double v[3];
	int pt_in_iso_crv=0;
	struct iso_curve *this_iso;

	if (mapping3d == MAP3D_CARTESIAN)
	{	 if (df_no_use_specs == 2)
			int_error("Need 1 or 3 columns for cartesian data", this_plot->token);
	}
	else
	{
		if (df_no_use_specs == 1)
			int_error("Need 2 or 3 columns for polar data", this_plot->token);
	}

	this_plot->num_iso_read = 0;
	this_plot->has_grid_topology = TRUE;

	/* we ought to keep old memory - most likely case
	 * is a replot, so it will probably exactly fit into
	 * memory already allocated ?
	 */
	if (this_plot->iso_crvs != NULL) {
		struct iso_curve *icrv, *icrvs = this_plot->iso_crvs;

		while (icrvs) {
			icrv = icrvs;
			icrvs = icrvs->next;
			iso_free(icrv);
		}
		this_plot->iso_crvs = NULL;
	}

	/* data file is already open */

	if (df_matrix)
		xdatum=df_3dmatrix(this_plot);
	else	{
		/*{{{  read surface from text file*/
		struct iso_curve *this_iso=iso_alloc(samples);
		struct coordinate GPHUGE *cp;
		double x,y,z;
		
		while ((j=df_readline(v,3)) != DF_EOF)  {
			if (j==DF_SECOND_BLANK)
				break;  /* two blank lines */
			if (j==DF_FIRST_BLANK) {
				/* one blank line */
				if (pt_in_iso_crv == 0) {
				    if (xdatum == 0)
					continue;
				    pt_in_iso_crv = xdatum;
				}
				if (xdatum > 0) {
				    this_iso->p_count = xdatum;
				    this_iso->next = this_plot->iso_crvs;
				    this_plot->iso_crvs = this_iso;
				    this_plot->num_iso_read++;
		
				    if (xdatum != pt_in_iso_crv)
					this_plot->has_grid_topology = FALSE;
		
				    this_iso = iso_alloc(pt_in_iso_crv);
				    xdatum = 0;
				    ydatum++;
				}
				continue;
			}
		
			/* its a data point or undefined */
		
		    if (xdatum >= this_iso->p_max) {
			/*
			 * overflow about to occur. Extend size of points[] array. We
			 * either double the size, or add 1000 points, whichever is a
			 * smaller increment. Note i=p_max.
			 */
			iso_extend(this_iso,
				   xdatum + (xdatum < 1000 ? xdatum : 1000));
		    }
		
		cp = this_iso->points + xdatum;
		
		if (j==DF_UNDEFINED) {
			cp->type=UNDEFINED;
			continue;
		}
		
		cp->type=INRANGE; /* unless we find out different */
		
		switch(mapping3d) {
			case MAP3D_CARTESIAN:
				switch(j) {
					case 1:
			    			x = xdatum;
			    			y = ydatum;
			    			z = v[0];
						break;
					case 3:
			    			x = v[0];
			    			y = v[1];
			    			z = v[2];
						break;
					default:
						{
							char msg[80];
							sprintf(msg, "Need 1 or 3 columns - line %d", df_line_number);
							int_error(msg, this_plot->token);
							return; /* avoid gcc -Wuninitialised for x,y,z */
						}
				}
				break;
			case MAP3D_SPHERICAL:
				if (j<2)
					int_error("Need 2 or 3 columns", this_plot->token);
				if (j<3)
					v[2]=1; /* default radius */
				if (angles_format == ANGLES_DEGREES) {
					v[0] *= DEG2RAD;	/* Convert to radians. */
					v[1] *= DEG2RAD;
				}
				x = v[2]*cos(v[0]) * cos(v[1]);
				y = v[2]*sin(v[0]) * cos(v[1]);
				z = v[2]*sin(v[1]);
				break;
			case MAP3D_CYLINDRICAL:
				if (j<2)
					int_error("Need 2 or 3 columns", this_plot->token);
				if (j<3)
					v[2]=1; /* default radius */
				if (angles_format == ANGLES_DEGREES) {
					v[0] *= DEG2RAD;	/* Convert to radians. */
				}
			    x = v[2]*cos(v[0]);
			    y = v[2]*sin(v[0]);
			    z = v[1];
			    break;
			 default:
			    int_error("Internal error : Unknown mapping type", NO_CARET);
			    return;
		}
		
		/* adjust for logscales. Set min/max and point types. store in cp */
		cp->type=INRANGE;
		/* cannot use continue, as macro is wrapped in a loop. I regard this as correct goto use */
		STORE_WITH_LOG_AND_FIXUP_RANGE(cp->x, x, cp->type, x_axis, NOOP, goto come_here_if_undefined );
		STORE_WITH_LOG_AND_FIXUP_RANGE(cp->y, y, cp->type, y_axis, NOOP, goto come_here_if_undefined );
		STORE_WITH_LOG_AND_FIXUP_RANGE(cp->z, z, cp->type, z_axis, NOOP, goto come_here_if_undefined );
		
			/* some may complain, but I regard this as the correct use of goto */
			come_here_if_undefined:
			++xdatum;
		}  /* end of whileloop - end of surface */
		
		if (xdatum > 0) {
		    this_plot->num_iso_read++;	/* Update last iso. */
		    this_iso->p_count = xdatum;
		
		    this_iso->next = this_plot->iso_crvs;
		    this_plot->iso_crvs = this_iso;
		
		    if (xdatum != pt_in_iso_crv)
			this_plot->has_grid_topology = FALSE;
		
		} else {
		    iso_free(this_iso);	/* Free last allocation. */
		}
		
		if (dgrid3d && this_plot->num_iso_read > 0)
			grid_nongrid_data(this_plot);
		/*}}}*/
	}

    if (this_plot->num_iso_read <= 1)
	this_plot->has_grid_topology = FALSE;
    if (this_plot->has_grid_topology && !hidden3d) {
	struct iso_curve *new_icrvs = NULL;
	int             num_new_iso = this_plot->iso_crvs->p_count, len_new_iso = this_plot->num_iso_read;

	/* Now we need to set the other direction (pseudo) isolines. */
	for (i = 0; i < num_new_iso; i++) {
	    struct iso_curve *new_icrv = iso_alloc(len_new_iso);

	    new_icrv->p_count = len_new_iso;

	    for (j = 0, this_iso = this_plot->iso_crvs;
		 this_iso != NULL;
		 j++, this_iso = this_iso->next) {
		/* copy whole point struct to get type too.
		 * wasteful for windows, with padding */
		/* more efficient would be extra pointer to same struct */
		new_icrv->points[j]=this_iso->points[i];
	    }

	    new_icrv->next = new_icrvs;
	    new_icrvs = new_icrv;
	}

	/* Append the new iso curves after the read ones. */
	for (this_iso = this_plot->iso_crvs;
	     this_iso->next != NULL;
	     this_iso = this_iso->next);
	    this_iso->next = new_icrvs;
    }

}



static void print_3dtable(pcount)
int pcount;
{
    register struct surface_points *this_plot;
    int             i, curve,surface;
    struct iso_curve *icrvs;
	struct coordinate GPHUGE *points;

    for (surface=0, this_plot=first_3dplot ; surface < pcount; 
		this_plot=this_plot->next_sp, surface++){
		fprintf(outfile, "\n#Surface %d of %d surfaces\n", surface, pcount);
		icrvs = this_plot->iso_crvs;
		curve = 0;

		if (draw_surface) {
		    /* only the curves in one direction */
		    while(icrvs && curve < this_plot->num_iso_read){
			fprintf(outfile, "\n#IsoCurve %d, %d points\n#x y z type\n", curve, icrvs->p_count);
			for(i=0, points = icrvs->points; i < icrvs->p_count; i++){
	    		fprintf(outfile, "%g %g %g %c\n",
		    	points[i].x,
		    	points[i].y,
		    	points[i].z,
		    	points[i].type == INRANGE ? 'i'
		    	: points[i].type == OUTRANGE ? 'o'
		    	: 'u');
			}
			icrvs = icrvs->next;
			curve++;
		    }
		    putc('\n', outfile);
		}

		if (draw_contour) {
			int number=0;
			struct gnuplot_contours *c=this_plot->contours;
			while (c) {
				int count=c->num_pts;
				struct coordinate GPHUGE *p=c->coords;
				if (c->isNewLevel)
					/* dont display count - contour split across chunks */
					/* put # in case user wants to use it for a plot */
					/* double blank line to allow plot ... index ... */
					fprintf(outfile, "\n# Contour %d, label:%s\n", number++, c->label);
				for ( ; --count >= 0 ; ++p)
					fprintf(outfile, "%g %g %g\n", p->x, p->y, p->z);
				putc('\n', outfile);  /* blank line between segments of same contour */
				c=c->next;
			}
		}			
	}
    fflush(outfile);
}



#define SET_DUMMY_RANGE(AXIS) \
do{\
 if (parametric || polar) { \
  t_min = tmin; t_max = tmax;\
 } else if (log_array[AXIS]) {\
  if (min_array[AXIS] <= 0.0 || max_array[AXIS] <= 0.0)\
   int_error("x/x2 range must be greater than 0 for log scale!", NO_CARET);\
  t_min = log(min_array[AXIS])/log_base_array[AXIS]; t_max = log(max_array[AXIS])/log_base_array[AXIS];\
 } else {\
  t_min = min_array[AXIS]; t_max = max_array[AXIS];\
 }\
 t_step = (t_max - t_min) / (samples - 1); \
}while(0)


/*
 * This parses the splot command after any range specifications. To support
 * autoscaling on the x/z axis, we want any data files to define the x/y
 * range, then to plot any functions using that range. We thus parse the
 * input twice, once to pick up the data files, and again to pick up the
 * functions. Definitions are processed twice, but that won't hurt.
 * div - okay, it doesn't hurt, but every time an option as added for
 * datafiles, code to parse it has to be added here. Change so that
 * we store starting-token in the plot structure.
 */
static void eval_3dplots()
{
	int    i, j;
	struct surface_points **tp_3d_ptr;
	int    start_token, end_token;
	int    begin_token;
	TBOOLEAN        some_data_files = FALSE, some_functions=FALSE;
	int             plot_num, line_num, point_num, crnt_param = 0;	/* 0=z, 1=y, 2=x */
	char           *xtitle;
	char           *ytitle;
	
	/* Reset first_3dplot. This is usually done at the end of this function.
	 * If there is an error within this function, the memory is left allocated,
	 * since we cannot call sp_free if the list is incomplete
	 */
	first_3dplot=NULL;
	
	/* put stuff into arrays to simplify access */
	INIT_ARRAYS(FIRST_X_AXIS, xmin, xmax, autoscale_lx, is_log_x, base_log_x, log_base_log_x, 0);
	INIT_ARRAYS(FIRST_Y_AXIS, ymin, ymax, autoscale_ly, is_log_y, base_log_y, log_base_log_y, 0);
	INIT_ARRAYS(FIRST_Z_AXIS, zmin, zmax, autoscale_lz, is_log_z, base_log_z, log_base_log_z, 1);
	
	x_axis=FIRST_X_AXIS;
	y_axis=FIRST_Y_AXIS;
	z_axis=FIRST_Z_AXIS;
	
	tp_3d_ptr = &(first_3dplot);
	plot_num = 0;
	line_num = 0;		/* default line type */
	point_num = 0;		/* default point type */
	
	xtitle = NULL;
	ytitle = NULL;
	
	begin_token = c_token;
	
	/*** First Pass: Read through data files ***/
	/*
	 * This pass serves to set the x/yranges and to parse the command, as
	 * well as filling in every thing except the function data. That is done
	 * after the x/yrange is defined.
	 */
	while (TRUE) {
		if (END_OF_COMMAND)
			int_error("function to plt3d expected", c_token);

		start_token = c_token;
		
		if (is_definition(c_token)) {
			define();
		} else {
			int specs;
			struct surface_points *this_plot;
			
			if (isstring(c_token)) {	/* data file to plot */

				/*{{{  data file*/
				if (parametric && crnt_param != 0)
					int_error("previous parametric function not fully specified",
					  c_token);
				
				if (!some_data_files) {
					if (autoscale_lx & 1) {
						min_array[FIRST_X_AXIS] = VERYLARGE;
		    		}
				
					if (autoscale_lx & 2) {
						max_array[FIRST_X_AXIS] = -VERYLARGE;
					}
				
					if (autoscale_ly & 1) {
						min_array[FIRST_Y_AXIS] = VERYLARGE;
					}
				
					if (autoscale_ly & 2) {
						max_array[FIRST_Y_AXIS] = -VERYLARGE;
					}
				
					some_data_files = TRUE;
				}
				
				if (*tp_3d_ptr)
					this_plot = *tp_3d_ptr;
				else {		/* no memory malloc()'d there yet */
					/* Allocate enough isosamples and samples */
					this_plot = sp_alloc(0, 0, 0, 0);
					*tp_3d_ptr = this_plot;
				}
				
				this_plot->plot_type = DATA3D;
				this_plot->plot_style = data_style;
				
				specs = df_open(3);
				/* parses all datafile-specific modifiers */
				/* we will load the data after parsing title,with,... */
				this_plot->token = end_token = c_token-1;  /* for capture to key */
				/* this_plot->token is temporary, for errors in get_3ddata() */
				
				if (datatype[FIRST_X_AXIS]==TIME)
				{
					if (specs<3)
						int_error("Need full using spec for x time data", c_token);
					df_timecol[0]=1;
				}
				
				if (datatype[FIRST_Y_AXIS]==TIME)
				{
					if (specs<3)
						int_error("Need full using spec for y time data", c_token);
					df_timecol[1]=1;
				}
				
				if (datatype[FIRST_Z_AXIS]==TIME)
				{
					if (specs<3)
						df_timecol[0]=1;
					else
						df_timecol[2]=1;
				}
				/*}}}*/

			} else {		/* function to plot */

				/*{{{  function*/
				++plot_num;
				if (parametric)	/* Rotate between x/y/z axes */
					crnt_param = (crnt_param + 2) % 3;  /* +2 same as -1, but beats -ve problem */
				
				if (*tp_3d_ptr) {
					this_plot = *tp_3d_ptr;
					if (!hidden3d)
						sp_replace(this_plot, samples_1, iso_samples_1,
  						               samples_2, iso_samples_2);
					else
						sp_replace(this_plot, iso_samples_1, 0,
  						                     0, iso_samples_2);
				
				} else {	/* no memory malloc()'d there yet */
					/* Allocate enough isosamples and samples */
					if (!hidden3d)
						this_plot = sp_alloc(samples_1, iso_samples_1,
						                     samples_2, iso_samples_2);
					else
						this_plot = sp_alloc(iso_samples_1, 0,
						            0, iso_samples_2);
					*tp_3d_ptr = this_plot;
				}
				
				this_plot->plot_type = FUNC3D;
				this_plot->has_grid_topology = TRUE;
				this_plot->plot_style = func_style;
				this_plot->num_iso_read = iso_samples_2;
				dummy_func = &plot_func;
				plot_func.at = temp_at();
				dummy_func=NULL;
				/* ignore it for now */
				some_functions=TRUE;
				end_token = c_token - 1;
				/*}}}*/

			}  /* end of IS THIS A FILE OR A FUNC block */


			/*{{{  title*/
			if (this_plot->title) {
				free(this_plot->title);
				this_plot->title=NULL;
			}
				
				
			if (almost_equals(c_token, "t$itle")) {
	/*			if (!isstring(++c_token))
					int_error("Expected title", c_token);
				m_quote_capture(&(this_plot->title), c_token, c_token);
	*/
				if (parametric) {
					if (crnt_param != 0)
						int_error("\"title\" allowed only after parametric function fully specified",c_token);
					else {
						if (xtitle != NULL)
							xtitle[0] = '\0';       /* Remove default title . */
						if (ytitle != NULL)
							ytitle[0] = '\0';       /* Remove default title . */
					}
				}
				if (isstring(++c_token))
					m_quote_capture(&(this_plot->title), c_token, c_token);
				else
					int_error("expecting \"title\" for plot", c_token);
				/* end of new method */
				++c_token;
			} else if (almost_equals(c_token,"not$itle")) {
				if (xtitle != NULL)
					xtitle[0] = '\0';
				if (ytitle != NULL)
					ytitle[0] = '\0';
				/*   this_plot->title=NULL;   */
				++c_token;
			} else {
				m_capture(&(this_plot->title), start_token, end_token);
				if (crnt_param == 2)
					xtitle = this_plot->title;
				else if (crnt_param == 1)
					ytitle = this_plot->title;
			}
			/*}}}*/
	    
	    
			/*{{{  line types, widths, ...*/
			this_plot->lp_properties.l_type = line_num;
			this_plot->lp_properties.p_type = point_num;
			
			if (almost_equals(c_token, "w$ith")) {
				this_plot->plot_style = get_style();
			}
			
			/* pick up line/point specs
			 * - point spec allowed if style uses points, ie style&2 != 0
			 * - keywords are optional
			 */
			LP_PARSE(this_plot->lp_properties, 1, this_plot->plot_style & 2,
			   line_num, point_num);
			
			/* allow old-style syntax too - ignore case lt 3 4 for example */
			if (!equals(c_token, ",") && !END_OF_COMMAND)
			{
				struct value t;
				this_plot->lp_properties.l_type =
				this_plot->lp_properties.p_type = (int) real(const_express(&t)) - 1;
				
				if (!equals(c_token, ",") && !END_OF_COMMAND)
					this_plot->lp_properties.p_type = (int) real(const_express(&t)) - 1;
				}
			
			if (this_plot->plot_style & 2) /* lines, linesp, ... */
				if (crnt_param == 0)
					point_num +=
					   1 + (draw_contour != 0)
					   + (hidden3d != 0);
						
			if (crnt_param == 0)
				line_num += 1 + (draw_contour != 0)
				         + (hidden3d != 0);
			/*}}}*/
			
			
			/* now get the data... having to think hard here...
			 * first time through, we fill in this_plot. For second
			 * surface in file, we have to allocate another surface
			 * struct. BUT we may allocate this store only to
			 * find that it is merely some blank lines at end of file
			 * tp_3d_ptr is still pointing at next field of prev. plot,
			 * before :    prev_or_first -> this_plot -> possible_preallocated_store
			 *                tp_3d_ptr--^
			 * after  :    prev_or_first -> first -> second -> last -> possibly_more_store
			 *                                        tp_3d_ptr ----^
			 * if file is empty, tp_3d_ptr is not moved. this_plot continues
			 * to point at allocated storage, but that will be reused later
			 */
			
			assert(this_plot == *tp_3d_ptr);
			
			if (this_plot->plot_type == DATA3D) {
				/*{{{  read data*/
				/* remember settings for second surface in file */
				struct lp_style_type *these_props = &(this_plot->lp_properties);
				enum PLOT_STYLE this_style=this_plot->plot_style;
				
				int this_token=this_plot->token;
				while (!df_eof)
				{
					this_plot = *tp_3d_ptr;
					assert(this_plot != NULL);
				
					/* dont move tp_3d_ptr until we are sure we
					 * have read a surface
					 */
					this_plot->token=this_token; /* used by get_3ddata() */
					get_3ddata(this_plot);
					this_plot->token=c_token; /* for second pass */
							
					if (this_plot->num_iso_read==0)
						/* probably df_eof, in which case we
						 * will leave loop. if not eof, then
						 * how come we got no surface ? - retry
						 * in neither case do we update tp_3d_ptr
						 */
						continue;
							
					/* okay, we have read a surface */
					++plot_num;
					tp_3d_ptr = &(this_plot->next_sp);
					if (df_eof)
						break;
							
					/* there might be another surface so allocate
					 * and prepare another surface structure
					 * This does no harm if in fact there are
					 * no more surfaces to read
					 */
					 
					if ( (this_plot=*tp_3d_ptr) != NULL ) {
						if (this_plot->title) {
							free(this_plot->title);
							this_plot->title = NULL;
						}
					} else {
						/* Allocate enough isosamples and samples */
						this_plot = *tp_3d_ptr = sp_alloc(0, 0, 0, 0);
					}
					
					this_plot->plot_type=DATA3D;
					this_plot->plot_style=this_style;
					this_plot->lp_properties = *these_props; /* struct copy */
				}
				df_close();
				/*}}}*/

			} else { /* not a data file */
				tp_3d_ptr = &(this_plot->next_sp);
				this_plot->token = c_token;  /* store for second pass */
			}

		}  /* !is_definition() : end of scope of this_plot */

    
		if (equals(c_token, ","))
			c_token++;
		else
			break;
	    
    } /* while(TRUE), ie first pass */


	if (parametric && crnt_param != 0)
		int_error("parametric function not fully specified", NO_CARET);


	/*** Second Pass: Evaluate the functions ***/
	/*
	 * Everything is defined now, except the function data. We expect no
	 * syntax errors, etc, since the above parsed it all. This makes the code
	 * below simpler. If autoscale_ly, the yrange may still change.
	 * - eh ?  - z can still change.  x/y/z can change if we are parametric ??
	 */

	if (some_functions) {

		/* I've changed the controlled variable in fn plots to u_min etc since
		 * it's easier for me to think parametric - 'normal' plot is after all
		 * a special case. I was confused about x_min being both minimum of
		 * x values found, and starting value for fn plots.
		 */
		register double u_min, u_max, u_step, v_min, v_max, v_step;
		double uisodiff, visodiff;
		struct surface_points *this_plot;


		if (!parametric) {
			/*{{{  check ranges*/
			/* give error if xrange badly set from missing datafile error
			 * parametric fn can still set ranges
			 * if there are no fns, we'll report it later as 'nothing to plot'
			 */
			
			if (min_array[FIRST_X_AXIS] == VERYLARGE || max_array[FIRST_X_AXIS] == -VERYLARGE) {
			    int_error("x range is invalid", c_token);
			}
			if (min_array[FIRST_Y_AXIS] == VERYLARGE || max_array[FIRST_Y_AXIS] == -VERYLARGE) {
			    int_error("y range is invalid", c_token);
			}
			
			/* check that xmin -> xmax is not too small */
			FIXUP_RANGE(FIRST_X_AXIS, x);
			FIXUP_RANGE(FIRST_Y_AXIS, y);
			/*}}}*/
		}

		if (parametric && !some_data_files) {
			/*{{{  set ranges*/
			/* parametric fn can still change x/y range */
			if (autoscale_lx & 1)
				min_array[FIRST_X_AXIS] = VERYLARGE;
			if (autoscale_lx & 2)
				max_array[FIRST_X_AXIS] = -VERYLARGE;
			if (autoscale_ly & 1)
				min_array[FIRST_Y_AXIS] = VERYLARGE;
			if (autoscale_ly & 2)
				max_array[FIRST_Y_AXIS] = -VERYLARGE;
			/*}}}*/
		}

		if (parametric) {
			u_min=umin;
			u_max=umax;
			v_min=vmin;
			v_max=vmax;
 	   } else {
			/*{{{  figure ranges, taking logs etc into account*/
			if (is_log_x) {
				if (min_array[FIRST_X_AXIS] <= 0.0 || max_array[FIRST_X_AXIS] <= 0.0)
					int_error("x range must be greater than 0 for log scale!", NO_CARET);
				u_min = log(min_array[FIRST_X_AXIS])/log_base_log_x;
				u_max = log(max_array[FIRST_X_AXIS])/log_base_log_x;
			} else {
				u_min = min_array[FIRST_X_AXIS];
				u_max = max_array[FIRST_X_AXIS];
			}
			
			if (is_log_y) {
				if (min_array[FIRST_Y_AXIS] <= 0.0 || max_array[FIRST_Y_AXIS] <= 0.0)
					int_error("y range must be greater than 0 for log scale!", NO_CARET);
				v_min = log(min_array[FIRST_Y_AXIS])/log_base_log_y;
				v_max = log(max_array[FIRST_Y_AXIS])/log_base_log_y;
			} else {
				v_min = min_array[FIRST_Y_AXIS];
				v_max = max_array[FIRST_Y_AXIS];
			}
			/*}}}*/
 	   }
		
		
		if (samples_1 < 2 || samples_2 < 2 || iso_samples_1 < 2 || iso_samples_2 < 2)
			int_error("samples or iso_samples < 2. Must be at least 2.", NO_CARET);
		
		
 	   /* start over */
 	   this_plot = first_3dplot;
 	   c_token = begin_token;
		
 	   /* why do attributes of this_plot matter ? */
 	   
		if (this_plot && this_plot->has_grid_topology && hidden3d) {
			u_step = (u_max - u_min) / (iso_samples_1 - 1);
			v_step = (v_max - v_min) / (iso_samples_2 - 1);
		} else {
			u_step = (u_max - u_min) / (samples_1 - 1);
			v_step = (v_max - v_min) / (samples_2 - 1);
		}
		
		uisodiff = (u_max - u_min) / (iso_samples_1 - 1);
		visodiff = (v_max - v_min) / (iso_samples_2 - 1);
		
		
		/* Read through functions */
		while (TRUE) {
			if (is_definition(c_token)) {
				define();
			} else {
		
				if (!isstring(c_token)) { /* func to plot */
					/*{{{  evaluate function*/
					struct iso_curve *this_iso = this_plot->iso_crvs;
					struct coordinate GPHUGE *points = this_iso->points;
					int num_sam_to_use, num_iso_to_use;
					
					if (parametric)
						crnt_param = (crnt_param + 2) % 3;
					
					dummy_func = &plot_func;
					plot_func.at = temp_at();	/* reparse function */
					dummy_func=NULL;
					num_iso_to_use = iso_samples_2;
					
					if (!(this_plot->has_grid_topology && hidden3d))
						num_sam_to_use = samples_1;
					else
						num_sam_to_use = iso_samples_1;
					
					for (j = 0; j < num_iso_to_use; j++) {
						double y = v_min + j * visodiff;
						/* if (is_log_y) PEM fix logscale y axis */
						/* y = pow(log_base_log_y,y); 26-Sep-89 */
						/* parametric => NOT a log quantity (?) */
						(void) Gcomplex(&plot_func.dummy_values[1],
						   !parametric && is_log_y ? pow(base_log_y, y) : y,
						   0.0);
						
						for (i = 0; i < num_sam_to_use; i++) {
							double x = u_min + i * u_step;
							struct value a;
							double temp;
						
							/* if (is_log_x) PEM fix logscale x axis */
							/* x = pow(base_log_x,x); 26-Sep-89 */
							/* parametric => NOT a log quantity (?) */
							(void) Gcomplex(&plot_func.dummy_values[0],
							       !parametric && is_log_x ? pow(base_log_x, x) : x,
							       0.0);
					
							points[i].x = x;
							points[i].y = y;
					
							evaluate_at(plot_func.at, &a);
					
							if (undefined || (fabs(imag(&a)) > zero)) {
								points[i].type = UNDEFINED;
								continue;
							}
							temp = real(&a);
					
							points[i].type=INRANGE;
							STORE_WITH_LOG_AND_FIXUP_RANGE(points[i].z, temp, points[i].type,
							    crnt_param, NOOP, NOOP);
					
						}
						this_iso->p_count = num_sam_to_use;
						this_iso = this_iso->next;
						points = this_iso? this_iso->points: NULL;
					}
					
					if (!(this_plot->has_grid_topology && hidden3d)) {
						num_iso_to_use = iso_samples_1;
						num_sam_to_use = samples_2;
						for (i = 0; i < num_iso_to_use; i++) {
							double x = u_min + i * uisodiff;
							/* if (is_log_x) PEM fix logscale x axis */
							/* x = pow(base_log_x,x); 26-Sep-89 */
							/* if parametric, no logs involved - 3.6 */
							(void) Gcomplex(&plot_func.dummy_values[0],
								       (!parametric && is_log_x) ? pow(base_log_x, x) : x,
								       0.0);
							
							for (j = 0; j < num_sam_to_use; j++) {
								double y = v_min + j * v_step;
								struct value a;
								double temp;
								/* if (is_log_y) PEM fix logscale y axis */
								/* y = pow(base_log_y,y); 26-Sep-89 */
								(void) Gcomplex(&plot_func.dummy_values[1],
								 (!parametric && is_log_y) ? pow(base_log_y, y) : y,
								 0.0);
										
								points[j].x = x;
								points[j].y = y;
										
								evaluate_at(plot_func.at, &a);
										
								if (undefined || (fabs(imag(&a)) > zero)) {
									points[j].type = UNDEFINED;
									continue;
								}
								temp = real(&a);
						
								points[j].type=INRANGE;
								STORE_WITH_LOG_AND_FIXUP_RANGE(points[j].z, temp, points[j].type,
								    crnt_param, NOOP, NOOP);
							}
							this_iso->p_count = num_sam_to_use;
							this_iso = this_iso->next;
							points = this_iso ? this_iso->points : NULL;
						}
					}
					/*}}}*/
				}  /* end of ITS A FUNCTION TO PLOT */
		
				c_token = this_plot->token;  /* we saved it from first pass */
		
				/* one data file can make several plots */
				do
					this_plot = this_plot->next_sp;
				while (this_plot && this_plot->token == c_token);
		    
			} /* !is_definition */
		
			if (equals(c_token, ","))
				c_token++;
			else
				break;
		    
		} /* while(TRUE) */
		
		
		if (parametric) {
			/* Now actually fix the plot triplets to be single plots. */
			parametric_3dfixup(first_3dplot, &plot_num);
		}

	}  /* some functions */


	/* if first_3dplot is NULL, we have no functions or data at all.
	 * This can happen, if you type "splot x=5", since x=5 is a
	 * variable assignment
	 */

	if(plot_num == 0 || first_3dplot==NULL) {
		int_error("no functions or data to plot", c_token);
	}

	if (min_array[FIRST_X_AXIS] ==  VERYLARGE ||
	    max_array[FIRST_X_AXIS] == -VERYLARGE ||
	    min_array[FIRST_Y_AXIS] ==  VERYLARGE ||
	    max_array[FIRST_Y_AXIS] == -VERYLARGE ||
	    min_array[FIRST_Z_AXIS] ==  VERYLARGE ||
	    max_array[FIRST_Z_AXIS] == -VERYLARGE)
		int_error("All points undefined", NO_CARET);

	FIXUP_RANGE(FIRST_X_AXIS, x);
	FIXUP_RANGE(FIRST_Y_AXIS, y);
	FIXUP_RANGE(FIRST_Z_AXIS, z);
	
	FIXUP_RANGE_FOR_LOG(FIRST_X_AXIS, x);
	FIXUP_RANGE_FOR_LOG(FIRST_Y_AXIS, y);
	FIXUP_RANGE_FOR_LOG(FIRST_Z_AXIS, z);
	
	/* last parameter should take plot size into effect...
	 * probably needs to be moved to graph3d.c
	 * in the meantime, a value of 20 gives same behaviour
	 * as 3.5 which will do for the moment
	 */
	
	if (xtics) setup_tics(FIRST_X_AXIS, &xticdef, xformat, 20);
	if (ytics) setup_tics(FIRST_Y_AXIS, &yticdef, yformat, 20);
	if (ztics) setup_tics(FIRST_Z_AXIS, &zticdef, zformat, 20);

#define WRITEBACK(axis,min,max) \
if(range_flags[axis]&RANGE_WRITEBACK) \
  {if (auto_array[axis]&1) min=min_array[axis]; \
   if (auto_array[axis]&2) max=max_array[axis]; \
  }

	WRITEBACK(FIRST_X_AXIS,xmin,xmax)
	WRITEBACK(FIRST_Y_AXIS,ymin,ymax)
	WRITEBACK(FIRST_Z_AXIS,zmin,zmax)


	if(plot_num==0 || first_3dplot==NULL) {
		int_error("no functions or data to plot", c_token);
	}




    /* Creates contours if contours are to be plotted as well. */

	if (draw_contour) {
		struct surface_points *this_plot;
		for (this_plot = first_3dplot, i = 0;
		     i < plot_num;
		     this_plot = this_plot->next_sp, i++) {

			if (this_plot->contours) {
				struct gnuplot_contours *cntrs = this_plot->contours;
		
				while (cntrs) {
					struct gnuplot_contours *cntr = cntrs;
					cntrs = cntrs->next;
					free(cntr->coords);
					free(cntr);
				}
			}

			/* Make sure this one can be contoured. */
			if (!this_plot->has_grid_topology) {
				this_plot->contours = NULL;
				fprintf(stderr,"Notice: cannot contour non grid data!\n");
				/* changed from int_error by recommendation of rkc@xn.ll.mit.edu */
			} else if (this_plot->plot_type == DATA3D) {
				this_plot->contours = contour(
				    this_plot->num_iso_read,
				    this_plot->iso_crvs,
				    contour_levels, contour_pts,
				    contour_kind, contour_order,
				    levels_kind, levels_list);
			} else {
				this_plot->contours = contour(iso_samples_2,
				    this_plot->iso_crvs,
				    contour_levels, contour_pts,
				    contour_kind, contour_order,
				    levels_kind, levels_list);
			}
		}
	} /* draw_contour */


	/* perform the plot */

	if (strcmp(term->name, "table") == 0)
		print_3dtable(plot_num);
	else
	{
		START_LEAK_CHECK(); /* assert no memory leaks here ! */
		do_3dplot(first_3dplot, plot_num);
		END_LEAK_CHECK();
	}
    
	/* if we get here, all went well, so record the line for replot */
	if (plot_token != -1) {
		/* note that m_capture also frees the old replot_line */
		m_capture(&replot_line, plot_token, c_token-1);
		plot_token = -1;
	}

	sp_free(first_3dplot);
	first_3dplot = NULL;
}





static void 
parametric_3dfixup(start_plot, plot_num)
    struct surface_points *start_plot;
    int            *plot_num;
/*
 * The hardest part of this routine is collapsing the FUNC plot types in the
 * list (which are gauranteed to occur in (x,y,z) triplets while preserving
 * the non-FUNC type plots intact.  This means we have to work our way
 * through various lists.  Examples (hand checked):
 * start_plot:F1->F2->F3->NULL ==> F3->NULL
 * start_plot:F1->F2->F3->F4->F5->F6->NULL ==> F3->F6->NULL
 * start_plot:F1->F2->F3->D1->D2->F4->F5->F6->D3->NULL ==>
 * F3->D1->D2->F6->D3->NULL
 */
{
/*
 * I initialized *free_list with NULL, because my compiler warns some lines
 * later that it might be uninited. The code however seems to not access that
 * line in that case, but if I'm right, my change is OK and if not, this is a
 * serious bug in the code.
 *
 * x and y ranges now fixed in eval_3dplots
 */
    struct surface_points *xp, *new_list, *free_list = NULL;
    struct surface_points **last_pointer=&new_list;

    int             i, tlen, surface;
    char           *new_title;

    /*
     * Ok, go through all the plots and move FUNC3D types together.  Note:
     * this originally was written to look for a NULL next pointer, but
     * gnuplot wants to be sticky in grabbing memory and the right number of
     * items in the plot list is controlled by the plot_num variable.
     * 
     * Since gnuplot wants to do this sticky business, a free_list of
     * surface_points is kept and then tagged onto the end of the plot list
     * as this seems more in the spirit of the original memory behavior than
     * simply freeing the memory.  I'm personally not convinced this sort of
     * concern is worth it since the time spent computing points seems to
     * dominate any garbage collecting that might be saved here...
     */
    new_list = xp = start_plot;
    for (surface = 0; surface < *plot_num; surface++) {
      if (xp->plot_type == FUNC3D) {
	struct surface_points *yp = xp->next_sp;
	struct surface_points *zp = yp->next_sp;

	/* Here's a FUNC3D parametric function defined as three parts.
	 * Go through all the points and assign the x's and y's from xp and
	 * yp to zp. min/max already done
	 */
	struct iso_curve *xicrvs = xp->iso_crvs;
	struct iso_curve *yicrvs = yp->iso_crvs;
	struct iso_curve *zicrvs = zp->iso_crvs;

	(*plot_num) -= 2;

	assert(INRANGE < OUTRANGE && OUTRANGE < UNDEFINED);

	while (zicrvs) {
	    struct coordinate GPHUGE *xpoints = xicrvs->points, GPHUGE *ypoints = yicrvs->points, GPHUGE *zpoints = zicrvs->points;
	    for (i = 0; i < zicrvs->p_count; ++i) {
		zpoints[i].x = xpoints[i].z;
		zpoints[i].y = ypoints[i].z;
		if (zpoints[i].type < xpoints[i].type) zpoints[i].type = xpoints[i].type;
		if (zpoints[i].type < ypoints[i].type) zpoints[i].type = ypoints[i].type;

	    }
	    xicrvs = xicrvs->next;
	    yicrvs = yicrvs->next;
	    zicrvs = zicrvs->next;
	}

	/* Ok, fix up the title to include xp and yp plots. */
	if ( ( (xp->title && xp->title[0] != '\0') ||
	       (yp->title && yp->title[0] != '\0') ) && zp->title ) {
	    tlen = (xp->title ? strlen(xp->title) : 0) +
		(yp->title ? strlen(yp->title) : 0) +
		(zp->title ? strlen(zp->title) : 0) + 5;
	    new_title = gp_alloc((unsigned long) tlen, "string");
	    new_title[0] = 0;
	    if (xp->title && xp->title[0] != '\0') {
		strcat(new_title, xp->title);
		strcat(new_title, ", ");	/* + 2 */
	    }
	    if (yp->title && yp->title[0] != '\0') {
		strcat(new_title, yp->title);
		strcat(new_title, ", ");	/* + 2 */
	    }
	    strcat(new_title, zp->title);
	    free(zp->title);
	    zp->title = new_title;
	}

	/* add xp and yp to head of free list */
	assert(xp->next_sp == yp);
	yp->next_sp = free_list;
	free_list = xp;

	/* add zp to tail of new_list */
	*last_pointer = zp;
	last_pointer = &(zp->next_sp);
	xp=zp->next_sp;
      } else {  /* its a data plot */
	assert(*last_pointer == xp);  /* think this is true ! */
	last_pointer = &(xp->next_sp);
	xp=xp->next_sp;
      }
    }

    /* Ok, append free list and write first_plot */
    *last_pointer = free_list;
    first_3dplot=new_list;
}