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#ifndef lint
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static const char RCSid[] = "$Id: contour.c,v 1.4 2004/03/26 23:34:23 schorsch Exp $";
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#endif
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/*
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* contour.c - program to make contour plots, mappings from 3 to
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* 2 dimenstions.
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*
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* 8/22/86
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <ctype.h>
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#define MAXPTS 2048 /* maximum number of input points */
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typedef float DATAPT[3];
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DATAPT xyz[MAXPTS]; /* the input data */
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int xyzsiz;
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double zmin = 1e20; /* z minimum */
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double zmax = -1e20; /* z maximum */
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int minset = 0; /* user set minimum? */
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int maxset = 0; /* user set maximum? */
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int ncurves = 6; /* number of contours */
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static void getdata(FILE *fp);
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static int xycmp(const void* p1, const void* p2);
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static void contour(int n);
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static void crossings(double z);
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static void cross(DATAPT p0, DATAPT p1, double z);
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int
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main(
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int argc,
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char *argv[]
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)
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{
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FILE *fp;
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int i;
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for (i = 1; i < argc && argv[i][0] == '-'; i++)
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switch (argv[i][1]) {
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case 'n':
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ncurves = atoi(argv[++i]);
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break;
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case 'l':
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zmin = atof(argv[++i]);
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minset = 1;
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break;
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case 'u':
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zmax = atof(argv[++i]);
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maxset = 1;
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break;
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default:
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fprintf(stderr, "%s: unknown option: %s\n",
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argv[0], argv[i]);
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exit(1);
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}
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if (i == argc)
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getdata(stdin);
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else if (i < argc-1) {
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fprintf(stderr, "%s: too many file names\n", argv[0]);
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exit(1);
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} else if ((fp = fopen(argv[i], "r")) == NULL) {
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fprintf(stderr, "%s: file not found\n", argv[i]);
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exit(1);
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} else
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getdata(fp);
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qsort(xyz, xyzsiz, sizeof(DATAPT), xycmp); /* sort data */
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for (i = 0; i < ncurves; i++) /* do contours */
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contour(i);
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exit(0);
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}
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static void
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getdata( /* read input data */
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FILE *fp
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)
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{
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register int i;
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while (xyzsiz < MAXPTS) {
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for (i = 0; i < 3; i++)
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if (fscanf(fp, "%f", &xyz[xyzsiz][i]) != 1)
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break;
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if (i != 3)
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break;
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if (xyz[xyzsiz][2] < zmin) {
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if (minset) {
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continue;
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} else {
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zmin = xyz[xyzsiz][2];
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}
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}
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if (xyz[xyzsiz][2] > zmax) {
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if (maxset) {
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continue;
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} else {
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zmax = xyz[xyzsiz][2];
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}
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}
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xyzsiz++;
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}
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if (!feof(fp)) {
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fprintf(stderr, "Error reading input data\n");
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exit(1);
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}
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}
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static int
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xycmp( /* -1 if p1 < p2, 0 if equal, 1 if p1 > p2 */
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const void* p1,
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const void* p2
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)
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{
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const float* pp1 = p1;
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const float* pp2 = p2;
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if (pp1[0] > pp2[0])
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return(1);
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if (pp1[0] < pp2[0])
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return(-1);
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if (pp1[1] > pp2[1])
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return(1);
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if (pp1[1] < pp2[1])
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return(-1);
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return(0);
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}
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static void
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contour( /* make contour n */
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int n
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)
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{
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double z;
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z = (n+.5)*(zmax-zmin)/ncurves + zmin;
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printf("%clabel=\"%f\";\n", n+'A', z);
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printf("%cdata=\n", n+'A');
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crossings(z);
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printf(";\n");
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}
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static void
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crossings( /* find crossings for z */
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double z
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)
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{
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register DATAPT *p0, *p1;
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p0 = p1 = xyz;
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while (p0 < xyz+xyzsiz-2) {
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while (p1 < xyz+xyzsiz-2) {
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if (p0[0][0] < p1[0][0] && p0[0][1] <= p1[0][1])
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break;
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p1++;
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}
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if (p0[0][0] == p0[1][0])
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cross(p0[0], p0[1], z);
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if (p0[0][1] == p1[0][1])
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cross(p0[0], p1[0], z);
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p0++;
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}
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}
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static void
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cross( /* mark crossing between p0 and p1 */
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register DATAPT p0,
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register DATAPT p1,
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double z
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)
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{
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if (p1[2] - p0[2] == 0.0)
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return;
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z = (z - p0[2])/(p1[2] - p0[2]);
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if (z < 0.0 || z >= 1.0)
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return;
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printf("%e\t", p0[0]*(1.0 - z) + p1[0]*z);
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printf("%e\n", p0[1]*(1.0 - z) + p1[1]*z);
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}
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