geos_segment_intersection(a, b)
geos_orientation_index(a, point)
Arguments
- a, b
A list() representing segments in the form
list(x0, y0, x1, y1). List items with length 1 will be
recycled to the length of the longest item.
- point
A list() representing points in the form list(x, y).
Value
geos_segment_intersection() returns a list(x, y);
geos_orientation_index() returns -1, 0 or 1, depending if
the point lies to the right of (-1), is colinear with (0) or
lies to the left of (1) the segment (as judged from the start
of the segment looking towards the end).
Examples
geos_segment_intersection(
list(0, 0, 10, 10),
list(10, 0, 0, 10)
)
#> $x
#> [1] 5
#>
#> $y
#> [1] 5
#>
geos_orientation_index(
list(0, 0, 10, 10),
list(15, c(12, 15, 17))
)
#> [1] -1 0 1