| /* |
| Produce spline (uniform knots, second order) |
| from guiding points |
| */ |
| #include "mplot.h" |
| void splin(int mode, int num[], double *ff[]){ |
| int i, *np, n; |
| double xa, ya, xc, yc, *xp, *yp, *xp0, *yp0, *xpe, *ype; |
| double **fp; |
| np = num; |
| fp = ff; |
| while((n = *np++)){ |
| xp = *fp++; |
| yp = xp + 1; |
| xp0 = xp; |
| yp0 = yp; |
| xpe = xp0 + 2 * (n - 1); |
| ype = yp0 + 2 * (n - 1); |
| if (n < 3) { |
| plotline(*xp, *yp, *(xp + 2), *(yp + 2)); |
| continue; |
| } |
| if (mode == 4) { /*closed curve*/ |
| xa = 0.5 * (*xpe + *(xpe - 2)); |
| xc = 0.5 * (*xpe + *xp0); |
| ya = 0.5 * (*ype + *(ype - 2)); |
| yc = 0.5 * (*ype + *yp0); |
| parabola(xa, ya, xc, yc, *xpe, *ype); |
| xa = 0.5 * (*xpe + *xp0); |
| xc = 0.5 * (*(xp0 + 2) + *xp0); |
| ya = 0.5 * (*ype + *yp0); |
| yc = 0.5 * (*(yp0 + 2) + *yp0); |
| parabola(xa, ya, xc, yc, *xp0, *yp0); |
| } |
| else { /*open curve with multiple endpoints*/ |
| if (mode % 2) /*odd mode makes first point double*/ |
| plotline(*xp0,*yp0,0.5*(*xp0+*(xp0+2)),0.5*(*yp0+*(yp0+2))); |
| } |
| xp += 2; |
| yp += 2; |
| for (i = 1; i < (n - 1); i++, xp += 2, yp += 2) { |
| xa = 0.5 * (*(xp - 2) + *xp); |
| xc = 0.5 * ( *xp + *(xp + 2)); |
| ya = 0.5 * (*(yp - 2) + *yp); |
| yc = 0.5 * ( *yp + *(yp + 2)); |
| parabola(xa, ya, xc, yc, *xp, *yp); |
| } |
| if(mode >= 2 && mode != 4) |
| plotline(0.5*(*(xpe-2)+*xpe),0.5*(*(ype-2)+*ype),*xpe,*ype); |
| } |
| } |
