// 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} }