1 4314729d 2004-04-14 devnull /*
 2 4314729d 2004-04-14 devnull Produce spline (uniform knots, second order)
 3 4314729d 2004-04-14 devnull from guiding points
 4 4314729d 2004-04-14 devnull */
 5 4314729d 2004-04-14 devnull #include "mplot.h"
 6 4314729d 2004-04-14 devnull void splin(int mode, int num[], double *ff[]){
 7 4314729d 2004-04-14 devnull 	int	i,  *np, n;
 8 4314729d 2004-04-14 devnull 	double	xa, ya, xc, yc, *xp, *yp, *xp0, *yp0, *xpe, *ype;
 9 4314729d 2004-04-14 devnull 	double **fp;
10 4314729d 2004-04-14 devnull 	np = num;
11 4314729d 2004-04-14 devnull 	fp = ff;
12 4314729d 2004-04-14 devnull 	while((n = *np++)){
13 4314729d 2004-04-14 devnull 		xp = *fp++; 
14 4314729d 2004-04-14 devnull 		yp = xp + 1; 
15 4314729d 2004-04-14 devnull 		xp0 = xp; 
16 4314729d 2004-04-14 devnull 		yp0 = yp;
17 4314729d 2004-04-14 devnull 		xpe = xp0 + 2 * (n - 1); 
18 4314729d 2004-04-14 devnull 		ype = yp0 + 2 * (n - 1);
19 4314729d 2004-04-14 devnull 		if (n < 3) { 
20 4314729d 2004-04-14 devnull 			plotline(*xp, *yp, *(xp + 2), *(yp + 2)); 
21 4314729d 2004-04-14 devnull 			continue;
22 4314729d 2004-04-14 devnull 		}
23 4314729d 2004-04-14 devnull 		if (mode == 4) {	/*closed curve*/
24 4314729d 2004-04-14 devnull 			xa = 0.5 * (*xpe + *(xpe - 2)); 
25 4314729d 2004-04-14 devnull 			xc = 0.5 * (*xpe + *xp0);
26 4314729d 2004-04-14 devnull 			ya = 0.5 * (*ype + *(ype - 2)); 
27 4314729d 2004-04-14 devnull 			yc = 0.5 * (*ype + *yp0);
28 4314729d 2004-04-14 devnull 			parabola(xa, ya, xc, yc, *xpe, *ype);
29 4314729d 2004-04-14 devnull 			xa = 0.5 * (*xpe + *xp0); 
30 4314729d 2004-04-14 devnull 			xc = 0.5 * (*(xp0 + 2) + *xp0);
31 4314729d 2004-04-14 devnull 			ya = 0.5 * (*ype + *yp0); 
32 4314729d 2004-04-14 devnull 			yc = 0.5 * (*(yp0 + 2) + *yp0);
33 4314729d 2004-04-14 devnull 			parabola(xa, ya, xc, yc, *xp0, *yp0);
34 4314729d 2004-04-14 devnull 		}
35 4314729d 2004-04-14 devnull 		else {	/*open curve with multiple endpoints*/
36 4314729d 2004-04-14 devnull 			if (mode % 2) /*odd mode makes first point double*/
37 4314729d 2004-04-14 devnull 				plotline(*xp0,*yp0,0.5*(*xp0+*(xp0+2)),0.5*(*yp0+*(yp0+2)));
38 4314729d 2004-04-14 devnull 		}
39 4314729d 2004-04-14 devnull 		xp += 2; 
40 4314729d 2004-04-14 devnull 		yp += 2;
41 4314729d 2004-04-14 devnull 		for (i = 1; i < (n - 1); i++, xp += 2, yp += 2) {
42 4314729d 2004-04-14 devnull 			xa = 0.5 * (*(xp - 2) + *xp); 
43 4314729d 2004-04-14 devnull 			xc = 0.5 * ( *xp + *(xp + 2));
44 4314729d 2004-04-14 devnull 			ya = 0.5 * (*(yp - 2) + *yp); 
45 4314729d 2004-04-14 devnull 			yc = 0.5 * ( *yp + *(yp + 2));
46 4314729d 2004-04-14 devnull 			parabola(xa, ya, xc, yc, *xp, *yp);
47 4314729d 2004-04-14 devnull 		}
48 4314729d 2004-04-14 devnull 		if(mode >= 2 && mode != 4)
49 4314729d 2004-04-14 devnull 			plotline(0.5*(*(xpe-2)+*xpe),0.5*(*(ype-2)+*ype),*xpe,*ype);
50 4314729d 2004-04-14 devnull 	}
51 4314729d 2004-04-14 devnull }