/* Finds all tricircles specified point belongs to.
*
* @param d Delaunay triangulation
* @param p Point to be mapped
* @param n Pointer to the number of tricircles within `d' containing `p'
* (output)
* @param out Pointer to an array of indices of the corresponding triangles
* [n] (output)
*
* There is a standard search procedure involving search through triangle
* neighbours (not through vertex neighbours). It must be a bit faster due to
* the smaller number of triangle neighbours (3 per triangle) but may fail
* for a point outside convex hall.
*
* We may wish to modify this procedure in future: first check if the point
* is inside the convex hall, and depending on that use one of the two
* search algorithms. It not 100% clear though whether this will lead to a
* substantial speed gains because of the check on convex hall involved.
*/
void delaunay_circles_find(delaunay* d, point* p, int* n, int** out)
{
/*
* This flag was introduced as a hack to handle some degenerate cases. It
* is set to 1 only if the triangle associated with the first circle is
* already known to contain the point. In this case the circle is assumed
* to contain the point without a check. In my practice this turned
* useful in some cases when point p coincided with one of the vertices
* of a thin triangle.
*/
int contains = 0;
int i;
if (d->t_in == NULL) {
d->t_in = istack_create();
d->t_out = istack_create();
}
/*
* if there are only a few data points, do linear search
*/
if (d->ntriangles <= N_SEARCH_TURNON) {
istack_reset(d->t_out);
for (i = 0; i < d->ntriangles; ++i) {
if (circle_contains(&d->circles[i], p)) {
istack_push(d->t_out, i);
}
}
*n = d->t_out->n;
*out = d->t_out->v;
return;
}
/*
* otherwise, do a more complicated stuff
*/
/*
* It is important to have a reasonable seed here. If the last search
* was successful -- start with the last found tricircle, otherwhile (i)
* try to find a triangle containing p; if fails then (ii) check
* tricircles from the last search; if fails then (iii) make linear
* search through all tricircles
*/
if (d->first_id < 0 || !circle_contains(&d->circles[d->first_id], p)) {
/*
* if any triangle contains p -- start with this triangle
*/
d->first_id = delaunay_xytoi(d, p, d->first_id);
contains = (d->first_id >= 0);
/*
* if no triangle contains p, there still is a chance that it is
* inside some of circumcircles
*/
if (d->first_id < 0) {
int nn = d->t_out->n;
int tid = -1;
/*
* first check results of the last search
*/
for (i = 0; i < nn; ++i) {
tid = d->t_out->v[i];
if (circle_contains(&d->circles[tid], p))
break;
}
/*
* if unsuccessful, search through all circles
*/
if (tid < 0 || i == nn) {
double nt = d->ntriangles;
for (tid = 0; tid < nt; ++tid) {
if (circle_contains(&d->circles[tid], p))
break;
}
if (tid == nt) {
istack_reset(d->t_out);
*n = 0;
*out = NULL;
return; /* failed */
}
}
d->first_id = tid;
}
}
istack_reset(d->t_in);
istack_reset(d->t_out);
istack_push(d->t_in, d->first_id);
d->flags[d->first_id] = 1;
/*
* main cycle
*/
while (d->t_in->n > 0) {
int tid = istack_pop(d->t_in);
triangle* t = &d->triangles[tid];
if (contains || circle_contains(&d->circles[tid], p)) {
istack_push(d->t_out, tid);
for (i = 0; i < 3; ++i) {
int vid = t->vids[i];
int nt = d->n_point_triangles[vid];
int j;
for (j = 0; j < nt; ++j) {
int ntid = d->point_triangles[vid][j];
if (d->flags[ntid] == 0) {
istack_push(d->t_in, ntid);
d->flags[ntid] = 1;
}
}
}
}
contains = 0;
}
*n = d->t_out->n;
*out = d->t_out->v;
}
int main() {
char c;
int i, k = 0, t = 1;
double x, y;
FILE *fp = stdin;
double r[MAX][6];
char type[MAX];
while ((c = fgetc(fp)) != '*') {
if (c == 'r') {
for (i = 0; i < 4; i++) {
fscanf(fp, "%lf", &r[k][i]);
}
type[k++] = c;
} else if (c == 'c') {
for (i = 0; i < 3; i++) {
fscanf(fp, "%lf", &r[k][i]);
}
type[k++] = c;
} else if (c == 't') {
for (i = 0; i < 6; i++) {
fscanf(fp, "%lf", &r[k][i]);
}
type[k++] = c;
}
fgetc(fp);
}
bool seen;
while (fscanf(fp, "%lf %lf", &x, &y) == 2 && (x != 9999.9 || y != 9999.9)) {
seen = false;
for (i = 0; i < k; i++) {
if (type[i] == 'r') {
if (x > r[i][0] && x < r[i][2] && y < r[i][1] && y > r[i][3]) {
printf("Point %i is contained in figure %i\n", t, (i + 1));
seen = true;
}
} else if (type[i] == 'c') {
if (circle_contains(r[i][0], r[i][1], x, y, r[i][2]) ) {
printf("Point %i is contained in figure %i\n", t, (i + 1));
seen = true;
}
} else if (type[i] == 't') {
if (triangle_contains(r[i][0], r[i][1], r[i][2], r[i][3], r[i][4], r[i][5], x, y) ) {
printf("Point %i is contained in figure %i\n", t, (i + 1));
seen = true;
}
}
}
if (!seen) {
printf("Point %i is not contained in any figure\n", t);
}
t++;
}
fclose(fp);
return 0;
}
