JavaScript Get Point of Line Intersection
// line intercept math by Paul Bourke http://paulbourke.net/geometry/pointlineplane/
// Determine the intersection point of two line segments
// Return FALSE if the lines don't intersect
function intersect(x1, y1, x2, y2, x3, y3, x4, y4) {
// Check if none of the lines are of length 0
if ((x1 === x2 && y1 === y2) || (x3 === x4 && y3 === y4)) {
return false
}
denominator = ((y4 - y3) * (x2 - x1) - (x4 - x3) * (y2 - y1))
// Lines are parallel
if (denominator === 0) {
return false
}
let ua = ((x4 - x3) * (y1 - y3) - (y4 - y3) * (x1 - x3)) / denominator
let ub = ((x2 - x1) * (y1 - y3) - (y2 - y1) * (x1 - x3)) / denominator
// is the intersection along the segments
if (ua < 0 || ua > 1 || ub < 0 || ub > 1) {
return false
}
// Return a object with the x and y coordinates of the intersection
let x = x1 + ua * (x2 - x1)
let y = y1 + ua * (y2 - y1)
return {x, y}
}
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