static void sort_points (mc_point_t *A, int N) {
int i, j;
mc_point_t h, t;
if (N <= 0) {
return;
}
if (N == 1) {
if (cmp_points (&A[0], &A[1]) > 0) {
t = A[0];
A[0] = A[1];
A[1] = t;
}
return;
}
i = 0;
j = N;
h = A[j >> 1];
do {
while (cmp_points (&A[i], &h) < 0) { i++; }
while (cmp_points (&A[j], &h) > 0) { j--; }
if (i <= j) {
t = A[i]; A[i++] = A[j]; A[j--] = t;
}
} while (i <= j);
sort_points (A+i, N-i);
sort_points (A, j);
}
int partition(struct Point a[], int l, int r)
{
int i, j;
struct Point t, pivot;
pivot = a[l];
i = l;
j = r + 1;
while (1) {
do
++i;
while (cmp_points(&a[i], &pivot, NULL) < 1 && i <= r);
do
--j;
while (cmp_points(&a[j], &pivot, NULL) == 1);
if (i >= j)
break;
if (a[i].line1 != NULL) {
if (a[i].line1->p1 == &a[i])
a[i].line1->p1 = &a[j];
else
a[i].line1->p2 = &a[j];
}
if (a[j].line1 != NULL) {
if (a[j].line1->p1 == &a[j])
a[j].line1->p1 = &a[i];
else
a[j].line1->p2 = &a[i];
}
if (a[i].line2 != NULL) {
if (a[i].line2->p1 == &a[i])
a[i].line2->p1 = &a[j];
else
a[i].line2->p2 = &a[j];
}
if (a[j].line2 != NULL) {
if (a[j].line2->p1 == &a[j])
a[j].line2->p1 = &a[i];
else
a[j].line2->p2 = &a[i];
}
t = a[i];
a[i] = a[j];
a[j] = t;
}
if (a[l].line1 != NULL) {
if (a[l].line1->p1 == &a[l])
a[l].line1->p1 = &a[j];
else
a[l].line1->p2 = &a[j];
}
if (a[j].line1 != NULL) {
if (a[j].line1->p1 == &a[j])
a[j].line1->p1 = &a[l];
else
a[j].line1->p2 = &a[l];
}
if (a[l].line2 != NULL) {
if (a[l].line2->p1 == &a[l])
a[l].line2->p1 = &a[j];
else
a[l].line2->p2 = &a[j];
}
if (a[j].line2 != NULL) {
if (a[j].line2->p1 == &a[j])
a[j].line2->p1 = &a[l];
else
a[j].line2->p2 = &a[l];
}
t = a[l];
a[l] = a[j];
a[j] = t;
return j;
}
/** for all points initiate their vis line to the one directly below
*/
void init_vis(struct Point *points, int num_points, struct Line *lines,
int num_lines)
{
int i;
double d;
struct avl_table *tree = avl_create(cmp_points, NULL, NULL);
struct avl_traverser it;
struct Point *p;
double y1, y2;
struct Point *s1, *s2;
for (i = 0; i < num_points; i++) {
points[i].vis = NULL;
d = PORT_DOUBLE_MAX;
avl_t_init(&it, tree);
/* loop through the tree */
while ((p = avl_t_next(&it)) != NULL) {
if (segment1(p) == NULL && segment2(p) == NULL)
continue;
/* test for intersection and get the intersecting point */
if (segment1(p) != NULL &&
segment_intersect(segment1(p), &points[i], &y1) > -1) {
/* find the closest one below */
if (y1 < points[i].y && (points[i].y - y1) < d) {
d = points[i].y - y1;
points[i].vis = segment1(p);
}
}
if (segment2(p) != NULL &&
segment_intersect(segment2(p), &points[i], &y2) > -1) {
if (y2 < points[i].y && (points[i].y - y2) < d) {
d = points[i].y - y2;
points[i].vis = segment2(p);
}
}
} /* end loop */
s1 = s2 = NULL;
/* now if the other point is on the right, we can delete it */
if (segment1(&points[i]) != NULL &&
cmp_points(&points[i], other1(&points[i]), NULL) > 0) {
p = other1(&points[i]);
/* unless the other point of it is on the left */
if (segment1(p) != NULL && other1(p) != &points[i] &&
cmp_points(&points[i], other1(p), NULL) > 0)
s1 = avl_delete(tree, p);
else if (segment2(p) != NULL && other2(p) != &points[i] &&
cmp_points(&points[i], other2(p), NULL) > 0)
s1 = avl_delete(tree, p);
}
/* now if the other point is on the right, we can delete it */
if (segment2(&points[i]) != NULL &&
cmp_points(&points[i], other2(&points[i]), NULL) > 0) {
p = other2(&points[i]);
/* unless the other point of it is on the left */
if (segment1(p) != NULL && other1(p) != &points[i] &&
cmp_points(&points[i], other1(p), NULL) > 0)
s2 = avl_delete(tree, p);
else if (segment2(p) != NULL && other2(p) != &points[i] &&
cmp_points(&points[i], other2(p), NULL) > 0)
s2 = avl_delete(tree, p);
}
/* if both weren't deleted, it means there is at least one other
point on the left, so add the current */
/* also there is no point adding the point if there is no segment attached to it */
if ((s1 == NULL || s2 == NULL)) {
avl_insert(tree, &points[i]);
}
}
avl_destroy(tree, NULL);
}
