Shade plot demo

 #pragma _ipath "./"
 #include "plcdemos.h"
 
 #define XPTS    35		/* Data points in x */
 #define YPTS    46		/* Data points in y */
 
 PLFLT z[XPTS][YPTS], zmin, zmax;
 
 
 static void	plot1		(void);
 static void	plot2		(void);
 static void	f2mnmx		(PLFLT *, PLINT, PLINT, PLFLT *, PLFLT *);
 static void	cmap1_init1	(void);
 static void	cmap1_init2	(void);
 
 
 int
 main(int argc, char *argv[])
 {
     int i, j;
     PLFLT xx, yy;
 
 
     (void) plParseOpts(&argc, argv, PL_PARSE_FULL);
 
 
     cmap1_init2();
 
 
     plinit();
 
 
     for (i = 0; i < XPTS; i++) {
 	xx = (double) (i - (XPTS / 2)) / (double) (XPTS / 2);
 	for (j = 0; j < YPTS; j++) {
 	    yy = (double) (j - (YPTS / 2)) / (double) (YPTS / 2) - 1.0;
 
 	    z[i][j] = xx*xx - yy*yy + (xx - yy)/(xx*xx+yy*yy + 0.1);
 	}
     }
     f2mnmx(&z[0][0], XPTS, YPTS, &zmin, &zmax);
 
     plot1();
     plot2();
 
     plend();
     exit(0);
 }
 
 
 static void
 cmap1_init1(void)
 {
     PLFLT i[4], h[4], l[4], s[4];
 
     i[0] = 0;		    i[1] = 0.45;	    i[2] = 0.55;	    i[3] = 1;		
     h[0] = 260;		    h[1] = 260;		    h[2] = 20;		    h[3] = 20;		
 #if 1
     l[0] = 0.5;		    l[1] = 0.0;		    l[2] = 0.0;		    l[3] = 0.5;		#else
     plscolbg(255,255,255);
     l[0] = 0.5;		    l[1] = 1.0;		    l[2] = 1.0;		    l[3] = 0.5;		#endif
     s[0] = 1;		    s[1] = 1;		    s[2] = 1;		    s[3] = 1;		
     plscmap1l(0, 4, i, h, l, s, NULL);
 }
 
 
 static void
 cmap1_init2(void)
 {
     PLFLT i[4], h[4], l[4], s[4];
 
     i[0] = 0;		    i[1] = 0.45;	    i[2] = 0.55;	    i[3] = 1;		
     h[0] = 260;		    h[1] = 260;		    h[2] = 20;		    h[3] = 20;		
 #if 1
     l[0] = 0.6;		    l[1] = 0.0;		    l[2] = 0.0;		    l[3] = 0.6;		#else
     plscolbg(255,255,255);
     l[0] = 0.5;		    l[1] = 1.0;		    l[2] = 1.0;		    l[3] = 0.5;		#endif
     s[0] = 1;		    s[1] = 0.5;		    s[2] = 0.5;		    s[3] = 1;		
     plscmap1l(0, 4, i, h, l, s, NULL);
 }
 
 
 static void 
 plot1(void)
 {
     PLFLT shade_min, shade_max, sh_color;
     PLINT sh_cmap = 0, sh_width;
     PLINT min_color = 0, min_width = 0, max_color = 0, max_width = 0;
 
     pladv(0);
     plvpor(0.1, 0.9, 0.1, 0.9);
     plwind(-1.0, 1.0, -1.0, 1.0);
 
 
     shade_min = zmin + (zmax-zmin)*0.4;
     shade_max = zmin + (zmax-zmin)*0.6;
     sh_color = 7;
     sh_width = 2;
     min_color = 9;
     max_color = 2;
     min_width = 2;
     max_width = 2;
 
     plpsty(8);
     plshade1(&z[0][0], XPTS, YPTS, NULL, -1., 1., -1., 1., 
 	     shade_min, shade_max, 
 	     sh_cmap, sh_color, sh_width,
 	     min_color, min_width, max_color, max_width,
 	     plfill, 1, NULL, NULL);
 
     plcol0(1);
     plbox("bcnst", 0.0, 0, "bcnstv", 0.0, 0);
     plcol0(2);
     pllab("distance", "altitude", "Bogon flux");
 }
 
 
 static void 
 plot2(void)
 {
     PLFLT shade_min, shade_max, sh_color;
     PLINT sh_cmap = 0, sh_width;
     PLINT min_color = 0, min_width = 0, max_color = 0, max_width = 0;
     int i;
     sh_width = 2;
 
     pladv(0);
     plvpor(0.1, 0.9, 0.1, 0.9);
     plwind(-1.0, 1.0, -1.0, 1.0);
 
     
     for (i = 0; i < 10; i++) {
 	shade_min = zmin + (zmax - zmin) * i / 10.0;
 	shade_max = zmin + (zmax - zmin) * (i +1) / 10.0;
 	sh_color = i+6;
 	plpsty((i + 2) % 8 + 1);
 
 	plshade1(&z[0][0], XPTS, YPTS, NULL, -1., 1., -1., 1., 
 		 shade_min, shade_max, 
 		 sh_cmap, sh_color, sh_width,
 		 min_color, min_width, max_color, max_width,
 		 plfill, 1, NULL, NULL);
     }
 
     plcol0(1);
     plbox("bcnst", 0.0, 0, "bcnstv", 0.0, 0);
     plcol0(2);
     pllab("distance", "altitude", "Bogon flux");
 }
 
 
 #define F(a,b) (f[a*ny+b])
 
 static void
 f2mnmx(PLFLT *f, PLINT nx, PLINT ny, PLFLT *fmin, PLFLT *fmax)
 {
     int i, j;
 
     *fmax = F(0,0);
     *fmin = *fmax;
 
     for (i = 0; i < nx; i++) {
 	for (j = 0; j < ny; j++) {
             *fmax = MAX(*fmax, F(i, j));
             *fmin = MIN(*fmin, F(i, j));
 	}
     }
 }