trapezoidal.c (578B)
1 #include <u.h> 2 #include <libc.h> 3 #include "map.h" 4 5 static struct coord stdpar0, stdpar1; 6 static double k; 7 static double yeq; 8 9 static int 10 Xtrapezoidal(struct place *place, double *x, double *y) 11 { 12 *y = yeq + place->nlat.l; 13 *x = *y*k*place->wlon.l; 14 return 1; 15 } 16 17 proj 18 trapezoidal(double par0, double par1) 19 { 20 if(fabs(fabs(par0)-fabs(par1))<.1) 21 return rectangular(par0); 22 deg2rad(par0,&stdpar0); 23 deg2rad(par1,&stdpar1); 24 if(fabs(par1-par0) < .1) 25 k = stdpar1.s; 26 else 27 k = (stdpar1.c-stdpar0.c)/(stdpar0.l-stdpar1.l); 28 yeq = -stdpar1.l - stdpar1.c/k; 29 return Xtrapezoidal; 30 }