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TA贡献1804条经验 获得超8个赞
这是一个使用 vanilla javascript 而不是 d3 的演示,但我希望你会发现它很有用。
该函数getLengthForPoint(p,thePath)正在计算给定点 p 在路径上的距离。我正在设置一个变量let precision = 100;。根据路径的长度,您可能希望将此值更改为其他值。
还要记住,一条路径可以多次通过同一个点。这可能很棘手,并且可能会给您带来错误。
同样如您所知,您将获得到某个点的近似距离。在这个例子中,点p1 = {x:93.5,y:60}. 计算长度处的点具有以下坐标:{x:93.94386291503906,y: 59.063079833984375}
// some points on the path
let p1 = {x:93.5,y:60}
let p2 = {x:165,y:106}
//the total length of the path
let pathLength = thePath.getTotalLength();
let precision = 100;
let division = pathLength / precision;
function getLengthForPoint(p,thePath){
let theRecord = pathLength;
let theSegment;
for (let i = 0; i < precision; i++) {
// get a point on the path for thia distance
let _p = thePath.getPointAtLength(i * division);
// get the distance between the new point _p and the point p
let theDistance = dist(_p, p);
if (theDistance < theRecord) {
// if the distance is smaller than the record set the new record
theRecord = theDistance;
theSegment = i;
}
}
return(theSegment * division);
}
let theDistanceOnThePath = getLengthForPoint(p1,thePath);
//if you calculate the coords of a point at the calculated distance you'll see that is very near the point
console.log(thePath.getPointAtLength(theDistanceOnThePath));
let theDistanceBetween2PointsOnThePath = getLengthForPoint(p2,thePath) - getLengthForPoint(p1,thePath);
// a helper function to measure the distance between 2 points
function dist(p1, p2) {
let dx = p2.x - p1.x;
let dy = p2.y - p1.y;
return Math.sqrt(dx * dx + dy * dy);
}
svg{border:solid}
<svg viewBox="0 10 340 120">
<path id="thePath" fill="none" stroke="black" d="M10, 24Q10,24,40,67Q70,110,93.5,60Q117,10,123.5,76Q130,142,165,106Q200,70,235,106.5Q270,143, 320,24"></path>
<circle cx="93.5" cy="60" r="2" fill="red"/>
<circle cx="165" cy="106" r="2" fill="red"/>
</svg>
要获得路径上两点之间的距离,您可以执行以下操作:
let theDistanceBetween2PointsOnThePath = getLengthForPoint(p2,thePath) - getLengthForPoint(p1,thePath);
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