bool segments_intersect(segment s1, segment s2) {
line l1, l2; /* lines containing the input segments */
point p; /* intersection point */
points_to_line(s1.p1, s1.p2, &l1);
points_to_line(s2.p1, s2.p2, &l2);
if(same_lineQ(l1, l2)) /* overlapping or disjoint segments */
return( point_in_box(s1.p1, s2.p1, s2.p2) ||
point_in_box(s1.p2, s2.p1, s2.p2) ||
point_in_box(s2.p1, s1.p1, s1.p2) ||
point_in_box(s2.p2, s1.p1, s1.p2) );
if(parallelQ(l1, l2)) return(FALSE);
intersection_point(l1, l2, p);
return( point_in_box(p, s1.p1, s1.p2) && point_in_box(p, s2.p1, s2.p2) );
}
bool segments_intersect(segment s1, segment s2)
{
line l1, l2;
points_to_line(s1.p1, s1.p2, &l1);
points_to_line(s2.p1, s2.p2, &l2);
if (same_lineQ(l1, l2))
return (point_in_box(s1.p1, s2.p1, s2.p2) ||
point_in_box(s1.p2, s2.p1, s2.p2) ||
point_in_box(s2.p1, s1.p1, s1.p2) ||
point_in_box(s2.p1, s1.p1, s1.p2) );
if (parallelQ(l1, l2))
return false;
point2d p; // intersection point
intersection_point(l1, l2, p);
return (point_in_box(p, s1.p1, s1.p2) && point_in_box(p, s2.p1, s2.p2) );
}
main()
{
point p1,p2,q1,q2,i;
line l1,l2;
segment s1,s2,s3,s4;
while ( scanf("%lf %lf",&p1[X],&p1[Y]) != EOF ) {
scanf("%lf %lf",&p2[X],&p2[Y]);
scanf("%lf %lf",&q1[X],&q1[Y]);
scanf("%lf %lf",&q2[X],&q2[Y]);
/*
print_point(p1);
print_point(p2);
print_point(q1);
print_point(q2);
*/
points_to_segment(p1,p2,&s1);
points_to_segment(q1,q2,&s2);
points_to_line(p1,p2,&l1);
points_to_line(q1,q2,&l2);
print_segment(s1);
print_segment(s2);
/*
printf("slope and line tests\n");
point_and_slope_to_line(p1,-l1.a,&l3);
print_line(l3);
point_and_slope_to_line(p2,-l1.a,&l3);
print_line(l3);
point_and_slope_to_line(q1,-l2.a,&l3);
print_line(l3);
point_and_slope_to_line(q2,-l2.a,&l3);
print_line(l3);
*/
printf("segments_intersect test\n");
printf("%d\n", segments_intersect(s1,s2));
printf("intersection point\n");
intersection_point(l1,l2,i);
print_point(i);
/*
printf("closest point\n");
closest_point(p1,l1,i);
print_point(i);
closest_point(p2,l1,i);
print_point(i);
closest_point(q1,l1,i);
print_point(i);
closest_point(q2,l1,i);
print_point(i);
closest_point(p1,l2,i);
print_point(i);
closest_point(p2,l2,i);
print_point(i);
closest_point(q1,l2,i);
print_point(i);
closest_point(q2,l2,i);
print_point(i);
*/
printf("--------------------------------\n");
}
}
