git: 9front

ref: a0ba4c1f03a3f99fb17a9edf9b4448db49bb6c46
dir: /sys/src/cmd/map/libmap/aitoff.c/

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#include <u.h>
#include <libc.h>
#include "map.h"

#define Xaitwist Xaitpole.nlat
static struct place Xaitpole;

static int
Xaitoff(struct place *place, double *x, double *y)
{
	struct place p;
	copyplace(place,&p);
	p.wlon.l /= 2.;
	sincos(&p.wlon);
	norm(&p,&Xaitpole,&Xaitwist);
	Xazequalarea(&p,x,y);
	*x *= 2.;
	return(1);
}

proj
aitoff(void)
{
	latlon(0.,0.,&Xaitpole);
	return(Xaitoff);
}