/**
* Finds intersection point between two lines
* @param {number} x1 - point x coordinate
* @param {number} y1 - point y coordinate
* @param {number} x2 - point x coordinate
* @param {number} y2 - point y coordinate
* @param {number} x3 - point x coordinate
* @param {number} y3 - point y coordinate
* @param {number} x4 - point x coordinate
* @param {number} y4 - point y coordinate
* @returns {{x:Number,y:Number}} X and Y coordinates of intersection point.
* @example
* intersect(0,0,100,100,100,0,0,100)
* // returns {x:50,y:50}
*
*/
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
}
const 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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