Mesh plot demo

 #pragma _ipath "./"
 #include "plcdemos.h"
 
 #define XPTS    35		/* Data points in x */
 #define YPTS    46		/* Data points in y */
 #define LEVELS 10 
 
 static int opt[] = { DRAW_LINEXY, DRAW_LINEXY};
 
 static PLFLT alt[] = {33.0, 17.0};
 static PLFLT az[] = {24.0, 115.0};
 
 static char *title[4] =
 {
     "#frPLplot Example 11 - Alt=33, Az=24, Opt=3",
     "#frPLplot Example 11 - Alt=17, Az=115, Opt=3",
 };
 
 static void
 cmap1_init()
 {
   PLFLT i[2], h[2], l[2], s[2];
 
   i[0] = 0.0;		  i[1] = 1.0;		
   h[0] = 240;  h[1] = 0;
   l[0] = 0.6;
   l[1] = 0.6;
 
   s[0] = 0.8;
   s[1] = 0.8;
 
   plscmap1n(256);
   plscmap1l(0, 2, i, h, l, s, NULL);
 }
 
 
 int
 main(int argc, char *argv[])
 {
   int i, j, k;
   PLFLT *x, *y, **z;
   PLFLT xx, yy;
   int nlevel = LEVELS;
   PLFLT clevel[LEVELS];
   PLFLT zmin, zmax, step;
 
 
   (void) plParseOpts(&argc, argv, PL_PARSE_FULL);
 
 
   plinit();
 
   x = (PLFLT *) calloc(XPTS, sizeof(PLFLT));
   y = (PLFLT *) calloc(YPTS, sizeof(PLFLT));
 
   plAlloc2dGrid(&z, XPTS, YPTS);
   for (i = 0; i < XPTS; i++) {
     x[i] = 3. * (double) (i - (XPTS / 2)) / (double) (XPTS / 2);
   }
 
   for (i = 0; i < YPTS; i++)
     y[i] = 3.* (double) (i - (YPTS / 2)) / (double) (YPTS / 2);
 
   for (i = 0; i < XPTS; i++) {
     xx = x[i];
     for (j = 0; j < YPTS; j++) {
       yy = y[j];
       z[i][j] = 3. * (1.-xx)*(1.-xx) * exp(-(xx*xx) - (yy+1.)*(yy+1.)) -
 	10. * (xx/5. - pow(xx,3.) - pow(yy,5.)) * exp(-xx*xx-yy*yy) -
 	1./3. * exp(-(xx+1)*(xx+1) - (yy*yy));
 		 
       if(0) {	if (z[i][j] < -1.)
 	  z[i][j] = -1.;
       }
     }
   }
 
   plMinMax2dGrid(z, XPTS, YPTS, &zmax, &zmin);  
   step = (zmax - zmin)/(nlevel+1);
   for (i=0; i<nlevel; i++)
     clevel[i] = zmin + step + step*i;
 
   cmap1_init();
   for (k = 0; k < 2; k++) {
     for (i=0; i<4; i++) {
       pladv(0);
       plcol0(1);
       plvpor(0.0, 1.0, 0.0, 0.9);
       plwind(-1.0, 1.0, -1.0, 1.5);
       plw3d(1.0, 1.0, 1.2, -3.0, 3.0, -3.0, 3.0, zmin, zmax, alt[k], az[k]);
       plbox3("bnstu", "x axis", 0.0, 0,
 	     "bnstu", "y axis", 0.0, 0,
 	     "bcdmnstuv", "z axis", 0.0, 4);
 
       plcol0(2);
 
       if (i==0)
 	plmesh(x, y, z, XPTS, YPTS, opt[k]);
 
       else if (i==1)
 	plmesh(x, y, z, XPTS, YPTS, opt[k] | MAG_COLOR);
 
       else if (i==2)
 	plot3d(x, y, z, XPTS, YPTS, opt[k] | MAG_COLOR, 1);
 
       else if (i==3)
 	plmeshc(x, y, z, XPTS, YPTS, opt[k] | MAG_COLOR | BASE_CONT,
 		clevel, nlevel);
 
       plcol0(3);
       plmtex("t", 1.0, 0.5, 0.5, title[k]);
     }
   }
 
   
   free((void *) x);
   free((void *) y);
   plFree2dGrid(z, XPTS, YPTS);
 
   plend();
 
   exit(0);
 }