Subversion Repositories planix.SVN

/*
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);
        }
}