line.line.intersection: Determine intersection between two lines

In retistruct: Retinal Reconstruction Program

Description

Determine the intersection of two lines L1 and L2 in two dimensions, using the formula described by Weisstein.

Usage

line.line.intersection(P1, P2, P3, P4, interior.only = FALSE)

Arguments

P1	vector containing x,y coordinates of one end of L1
P2	vector containing x,y coordinates of other end of L1
P3	vector containing x,y coordinates of one end of L2
P4	vector containing x,y coordinates of other end of L2
interior.only	boolean flag indicating whether only intersections inside L1 and L2 should be returned.

Value

Vector containing x,y coordinates of intersection of L1 and L2. If L1 and L2 are parallel, this is infinite-valued. If interior.only is TRUE, then when the intersection does not occur between P1 and P2 and P3 and P4, a vector containing NAs is returned.

Author(s)

David Sterratt

Source

Weisstein, Eric W. "Line-Line Intersection." From MathWorld–A Wolfram Web Resource. http://mathworld.wolfram.com/Line-LineIntersection.html

Examples

## Intersection of two intersecting lines
line.line.intersection(c(0, 0), c(1, 1), c(0, 1), c(1, 0))

## Two lines that don't intersect
line.line.intersection(c(0, 0), c(0, 1), c(1, 0), c(1, 1))

Example output

Warning messages:
1: In rgl.init(initValue, onlyNULL) : RGL: unable to open X11 display
2: 'rgl_init' failed, running with rgl.useNULL = TRUE 
3: .onUnload failed in unloadNamespace() for 'rgl', details:
  call: fun(...)
  error: object 'rgl_quit' not found 
[1] 0.5 0.5
[1] Inf Inf

retistruct documentation built on April 4, 2020, 5:08 p.m.