#include <stdio.h>
#include <math.h>
#include <dist.h>
#include <string.h>

Rot2	irot2 = {{1.0, 0.0},
		  {0.0, 1.0}};

void
rinv2(Rot2 d, Rot2 s)
{
	Rot2 r;

	r[0][0] = s[0][0];
	r[1][1] = s[1][1];
	r[1][0] = s[0][1];
	r[0][1] = s[1][0];

	memmove(d, r, sizeof(r));
}

Point2
rmap2(Rot2 r, Point2 p)
{
	Point2 p2;

	p2.x = r[0][0]*p.x + r[0][1]*p.y;
	p2.y = r[1][0]*p.x + r[1][1]*p.y;

	return p2;
}

void
rmul2(Rot2 d, Rot2 s1, Rot2 s2)
{
	Rot2 r;
	int i;

	for (i = 0; i < 2; ++i) {
		r[i][0] = s1[i][0]*s2[0][0] +
				s1[i][1]*s2[1][0];
		r[i][1] = s1[i][0]*s2[0][1] +
				s1[i][1]*s2[1][1];
	}

	memcpy(d, r, sizeof(Rot2));
}

void
rrot2(Rot2 d, double t)
{
	double c, s;

	c = cos(t);
	s = sin(t);
	d[0][0] = d[1][1] = c;
	d[1][0] = s;
	d[0][1] = -s;
}

void	
rrand2(Rot2 r)
{
	rrot2(r, frand()*2*MYPI);
}