@logicflow/core
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LogicFlow, help you quickly create flowcharts
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JavaScript
/**
* 求两个线段交点入参：线段1端点: ab, 线段2端点： cd,
* @param a
* @param b
* @param c
* @param d
* @return：有交点返回交点 Point，无交点返回false
*/
export var getCrossPointOfLine = function (a, b, c, d) {
/** 1 解线性方程组, 求线段交点. * */
// 如果分母为0 则平行或共线, 不相交
var denominator = (b.y - a.y) * (d.x - c.x) - (a.x - b.x) * (c.y - d.y);
if (denominator === 0) {
return false;
}
// 线段所在直线的交点坐标 (x , y)
var x = ((b.x - a.x) * (d.x - c.x) * (c.y - a.y) +
(b.y - a.y) * (d.x - c.x) * a.x -
(d.y - c.y) * (b.x - a.x) * c.x) /
denominator;
var y = -((b.y - a.y) * (d.y - c.y) * (c.x - a.x) +
(b.x - a.x) * (d.y - c.y) * a.y -
(d.x - c.x) * (b.y - a.y) * c.y) / denominator;
/** 2 判断交点是否在两条线段上 * */
if (
// 交点在线段1上
(x - a.x) * (x - b.x) <= 0 &&
(y - a.y) * (y - b.y) <= 0 &&
// 且交点也在线段2上
(x - c.x) * (x - d.x) <= 0 &&
(y - c.y) * (y - d.y) <= 0) {
// 返回交点p
return {
x: x,
y: y,
};
}
// 否则不相交
return false;
};
/* 判断一个点是否在线段中
入参点：point, 线段起终点，start,end,
返回值： 在线段中true，否则false
*/
export var isInSegment = function (point, start, end) {
var x = point.x, y = point.y;
var startX = start.x, startY = start.y;
var endX = end.x, endY = end.y;
var k = (endY - startY) / (endX - startX);
var b = startY - k * startX;
return (((x >= startX && x <= endX) || (x <= startX && x >= endX)) &&
((y >= startY && y <= endY) || (y <= startY && y >= endY)) &&
Math.abs(y - k * x - b) < Number.EPSILON);
};