src/util/Triangulation.js
function intersectEdge(x0, y0, x1, y1, x, y) {
    if ((y > y0 && y > y1) || (y < y0 && y < y1)) {
        return -Infinity;
    }
    // Ignore horizontal line
    if (y1 === y0) {
        return -Infinity;
    }
    var dir = y1 < y0 ? 1 : -1;
    var t = (y - y0) / (y1 - y0);

    // Avoid winding error when intersection point is the connect point of two line of polygon
    if (t === 1 || t === 0) {
        dir = y1 < y0 ? 0.5 : -0.5;
    }

    var x_ = t * (x1 - x0) + x0;

    return x_;
}
function intersectEdge(x0, y0, x1, y1, x, y) {
    if ((y > y0 && y > y1) || (y < y0 && y < y1)) {
        return -Infinity;
    }
    // Ignore horizontal line
    if (y1 === y0) {
        return -Infinity;
    }
    var dir = y1 < y0 ? 1 : -1;
    var t = (y - y0) / (y1 - y0);

    // Avoid winding error when intersection point is the connect point of two line of polygon
    if (t === 1 || t === 0) {
        dir = y1 < y0 ? 0.5 : -0.5;
    }

    var x_ = t * (x1 - x0) + x0;

    return x_;
}
function intersectEdge ( x0 , y0 , x1 , y1 , x , y ) { if ( ( y > y0 && y > y1 ) || ( y < y0 && y < y1 ) ) { return - Infinity ; } // Ignore horizontal line if ( y1 === y0 ) { return - Infinity ; } var dir = y1 < y0 ? 1 : - 1 ; var t = ( y - y0 ) / ( y1 - y0 ) ; // Avoid winding error when intersection point is the connect point of two line of polygon if ( t === 1 || t === 0 ) { dir = y1 < y0 ? 0.5 : - 0.5 ; } var x_ = t * ( x1 - x0 ) + x0 ; return x_ ; }
From x,y point cast a ray to right. and intersect with edge x0, y0, x1, y1; Return x value of intersect point
From x y point cast a ray to right . and intersect with edge x0 y0 x1 y1 ; Return x value of intersect point