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#include <u.h>
#include <libc.h>
#include <draw.h>
#include "dat.h"
#include "fns.h"
Vector
Vec(double x, double y)
{
return (Vector){x, y};
}
Vector
addvec(Vector v, Vector u)
{
return (Vector){v.x+u.x, v.y+u.y};
}
Vector
subvec(Vector v, Vector u)
{
return (Vector){v.x-u.x, v.y-u.y};
}
Vector
mulvec(Vector v, double s)
{
return (Vector){v.x*s, v.y*s};
}
double
dotvec(Vector v, Vector u)
{
return v.x*u.x + v.y*u.y;
}
Vector
normvec(Vector v)
{
double len;
len = hypot(v.x, v.y);
if(len == 0)
return (Vector){0, 0};
v.x /= len;
v.y /= len;
return v;
}
Vector
rotatevec(Vector p, double θ, Vector c)
{
Vector r;
p = subvec(p, c);
r.x = p.x*cos(θ) - p.y*sin(θ);
r.y = p.x*sin(θ) + p.y*cos(θ);
r = addvec(r, c);
return r;
}
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