#include "geometry.h"

// dist is a fixed point with precission of 8 bits
// offs is where on the line segment xy0-xy1 the point's normale hits,
// range 0..65536 (but can extend, if normale hits line outside line segment)
static inline int
impl_dist_pl(int xp, int yp, int x0, int y0, int x1, int y1, int *offs)
{
        double r = (y1 - y0) * (y1 - y0) + (x1 - x0) * (x1 - x0);
        double q1 = (xp - x0) * (y1 - y0) - (yp - y0) * (x1 - x0);
        double q2 = (x1 - x0) * (xp - x0) + (y1 - y0) * (yp - y0);

        *offs = (int)((q2 *65336.0f) / r);
        return (int)( q1 * q1 * ((double)(y0 - y1) * (double)(y0 - y1) + (double)(x1 - x0) * (double)(x1 - x0)) * 256.0f / (r * r));
}

int
dist_pl(LPoint const * p, LLine const * l, int *offs)
{
    return impl_dist_pl(p->x, p->y, l->p0.x, l->p0.y, l->p1.x, l->p1.y, offs);
}

static inline int
impl_dist_pp(int x0, int y0, int x1, int y1 ) {
    return (y0-y1)*(y0-y1)+(x0-x1)*(x0-x1);
}

int
dist_pp(LPoint const * p0, LPoint const * p1) {
    return impl_dist_pp(p0->x,p0->y,p1->x,p1->y);
}

int
get_x_for_y(LPoint const * p0, LPoint const * p1, int y) {
    if (p1->x!=p0->x && p1->y!=p0->y) {
        double m = (double)(p1->y-p0->y) / (double)(p1->x-p0->x);
        return (int)((((double)y) - (double)(p0->y) + m * (double)p0->x)/m);
    }
    return p1->x;
}