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/* libgrbs - geometric rubber band sketch model
Copyright (C) 2021 Tibor 'Igor2' Palinkas
(Supported by NLnet NGI0 PET Fund in 2021)
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
Contact:
Project page: http://repo.hu/projects/libgrbs
lead developer: http://repo.hu/projects/pcb-rnd/contact.html
*/
#include <math.h>
#include "geo.h"
int grbs_bicycle_angles(double cx1, double cy1, double r1, double cx2, double cy2, double r2, double a[4], int cross)
{
double dx = cx2 - cx1, dy = cy2 - cy1;
double dlen, alpha, beta;
dlen = sqrt(dx*dx + dy*dy);
if (fabs(r2-r1) >= dlen)
return -1; /* degenerate case: bigger circle contains the smaller one; also catchec concentric */
if (cross) {
double tmp = (r1 + r2) / dlen;
if (tmp > 1.0)
return -1;
alpha = acos(tmp);
}
else {
double tmp = (r1 - r2) / dlen;
if (tmp < -1.0)
return -1;
alpha = acos(tmp);
}
beta = atan2(dy, dx);
a[0] = beta + alpha;
a[1] = beta - alpha;
if (cross) {
a[2] = beta + (GRBS_PI - alpha);
a[3] = beta - (GRBS_PI - alpha);
}
else {
a[2] = a[0];
a[3] = a[1];
}
if (a[0] < 0) a[0] += 2.0*GRBS_PI;
if (a[1] < 0) a[1] += 2.0*GRBS_PI;
if (a[2] < 0) a[2] += 2.0*GRBS_PI;
if (a[3] < 0) a[3] += 2.0*GRBS_PI;
return 0;
}
void grbs_gen_bicycle_idx(grbs_arc_t *arc, grbs_arc_t *next, int crossbelt, int arc_at_end, int *ai, int *ni)
{
double dx = next->parent_pt->x - arc->parent_pt->x;
double dy = next->parent_pt->y - arc->parent_pt->y;
double ex, ey, ang, cp;
/*
fprintf(stderr, "GEN: (%f;%f -> %f;%f)\n", arc->parent_pt->x, arc->parent_pt->y, next->parent_pt->x, next->parent_pt->y);
fprintf(stderr, " d: %f %f\n", dx, dy);
*/
ang = arc_at_end ? arc->sa + arc->da : arc->sa;
ex = cos(ang);
ey = sin(ang);
cp = dx*ey - dy*ex;
*ai = (cp < 0);
/*fprintf(stderr, " e: %f %f -> ai %f %d\n", ex, ey, cp, *ai);*/
ang = arc_at_end ? next->sa : next->sa + next->da;
ex = cos(ang);
ey = sin(ang);
cp = dx*ey - dy*ex;
*ni = (cp < 0) + 2;
/*fprintf(stderr, " e: %f %f -> ni %f %d\n", ex, ey, cp, *ni);*/
}
int grbs_angle_in_arc(double arc_sa, double arc_da, double ang, int inclusive)
{
double arc_ea;
static const double tolerance = 0.00000000001;
/* make sure angle is always positive */
if (ang < 0)
ang += 2.0 * GRBS_PI;
else if (ang > 2.0 * GRBS_PI)
ang -= 2.0 * GRBS_PI;
if (arc_da < 0) { /* swap endpoints so da is always positive */
arc_sa = arc_sa + arc_da;
arc_da = -arc_da;
}
if (arc_sa < 0)
arc_sa += 2.0*GRBS_PI;
arc_ea = arc_sa + arc_da;
/* if arc spans from some high value through zero, the end angle has
to be larger than 2*pi; if ang is under both start and end, that may
be the case so add a full circle to ang, last chance to get it in
range */
if ((arc_sa > ang) && (arc_ea > ang))
ang += 2.0*GRBS_PI;
if (inclusive) {
if ((ang >= arc_sa) && (ang <= arc_ea))
return 1;
}
else {
if (((ang-tolerance) > arc_sa) && ((ang+tolerance) < arc_ea))
return 1;
}
if (arc_ea > 2.0*GRBS_PI) {
ang += 2.0*GRBS_PI;
if (inclusive) {
if ((ang >= arc_sa) && (ang <= arc_ea))
return 1;
}
else {
if ((ang > arc_sa) && (ang < arc_ea))
return 1;
}
}
return 0;
}
double grbs_arc_get_delta(double sa, double ea, int dir)
{
double da;
if (dir > 0) {
da = ea - sa;
if (da < 0)
da = 2*GRBS_PI + da;
else if (da > 2*GRBS_PI)
da -= 2*GRBS_PI;
return da;
}
else {
da = sa - ea;
if (da < 0)
da = 2*GRBS_PI + da;
else if (da > 2*GRBS_PI)
da -= 2*GRBS_PI;
return -da;
}
}
int grbs_get_adir(double from_x, double from_y, double to_cx, double to_cy, double to_r, double to_a)
{
double vx = to_cx - from_x, vy = to_cy - from_y, asplit;
int top_side;
/* cut the circle in half by incoming centerline the see which half
the actual line hits */
asplit = atan2(vy, vx);
top_side = grbs_angle_in_arc(asplit, GRBS_PI, to_a, 1);
return top_side ? -1 : +1;
}
grbs_arc_t *grbs_next_arc_in_use(grbs_arc_t *arc)
{
for(arc = arc->link_point.next; arc != NULL; arc = arc->link_point.next)
if (arc->in_use)
return arc;
return NULL;
}
grbs_arc_t *grbs_prev_arc_in_use(grbs_arc_t *arc)
{
for(arc = arc->link_point.prev; arc != NULL; arc = arc->link_point.prev)
if (arc->in_use)
return arc;
return NULL;
}
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