Drag along path snap.svg

问题

Hello the answer to this question with this fiddle is perfect for what I need to do - drag something along a path. However they used Rapael - I'd like to update things and use snap.svg instead.

Replacing the reference from Raphael to Snap in this answer doesn't work - does anyone have any ideas why?

This is as far as I've got in this codepen - I want to have a 10 point shape - the outer points of which can move a long a path to the centre.

var s = Snap("#svg");
var paths = [], points = [], circles = [], lines = [], l = 0, searchDl = 1;

var dist = function (pt1, pt2) {
    var dx = pt1.x - pt2.x;
    var dy = pt1.y - pt2.y;
    return Math.sqrt(dx * dx + dy * dy);
};

var gradSearch = function (l0, pt, path) {
    var totLen = path.getTotalLength();
  l0 = l0 + totLen;
    var l1 = l0,
        dist0 = dist(path.getPointAtLength(l0 % totLen), pt),
        dist1,
        searchDir;
  
  console.log(dist0);

    if (dist(path.getPointAtLength((l0 - searchDl) % totLen), pt) > 
       dist(path.getPointAtLength((l0 + searchDl) % totLen), pt)) {
        searchDir = searchDl;
    } else {
        searchDir = -searchDl;
    }

    l1 += searchDir;
    dist1 = dist(path.getPointAtLength(l1 % totLen), pt);
  console.log(dist1);
    while (dist1 < dist0) {
        dist0 = dist1;
        l1 += searchDir;
        dist1 = dist(path.getPointAtLength(l1 % totLen), pt);
    }
    l1 -= searchDir;
    console.log(l1 % totLen);
    return (l1 % totLen);
};

var startCircleToPoly = function () {
    // storing original coordinates
    this.ox = this.attr("cx");
    this.oy = this.attr("cy");
    this.attr({opacity: 1});
};

var moveCircleToPoly = function (dx, dy) {
    var tmpPt = {
        x : this.ox + dx, 
        y : this.oy + dy
    };
  	var path = paths[this.data('int')];
    // move will be called with dx and dy
    l = gradSearch(l, tmpPt, path);
  	//console.log(l);
    pt = path.getPointAtLength(l);
    this.attr({cx: pt.x, cy: pt.y});
};

var endCircleToPoly = function () {
    // restoring state
    this.attr({opacity: 1});
};

for(var i = 1; i <= 10; i++){
  //polygon points
  points.push( s.select('#line' + i).attr('x2') + ' ' + s.select('#line' + i).attr('y2') ); 
  
  paths.push( s.path('M' + s.select('#line' + i).attr('x2') + ' ' + s.select('#line' + i).attr('y2') + ' L' + s.select('#line' + i).attr('x1') + ' ' + s.select('#line' + i).attr('y1')).attr({stroke: "blue"}) );
  
  lines.push(s.select('#line' + i).attr({'stroke' : ''}));
 
	//circles
	circles.push( s.circle(
  	s.select('#line'+i).attr('x2'),
		s.select('#line'+i).attr('y2'),5).attr({
    	fill: "red", 
    	id: "circle"+i,
    	style: {"cursor" : "pointer"}
  	}).data({int: i-1}).drag( moveCircleToPoly, startCircleToPoly, endCircleToPoly )
	);
}

//add poly
/*var poly = s.polygon(points);
poly.attr({
    id:"poly",
    fill:"#555555"
});
*/

<svg id="svg" version="1.1"  preserveAspectRatio="xMinYMin meet" class="svg-content" viewBox="-10.109 -107.67 400 400">

<line id="line1" fill="none" x1="82.196" y1="-17.513" x2="107.595" y2="-95.686"/>
<line id="line2" fill="none" x1="82.196" y1="-17.513" x2="148.689" y2="-65.827"/>
<line id="line3" fill="none" x1="82.196" y1="-17.513" x2="164.391" y2="-17.513"/>
<line id="line4" fill="none" x1="82.196" y1="-17.513" x2="148.689" y2="30.801"/>
<line id="line5" fill="none" x1="82.196" y1="-17.513" x2="107.595" y2="60.66"/>
<line id="line6" fill="none" x1="82.196" y1="-17.513" x2="56.796" y2="60.66"/>
<line id="line7" fill="none" x1="82.196" y1="-17.513" x2="15.699" y2="30.801"/>
<line id="line8" fill="none" x1="82.196" y1="-17.513" x2="0" y2="-17.513"/>
<line id="line9" fill="none" x1="82.196" y1="-17.513" x2="15.699" y2="-65.827"/>
<line id="line10" fill="none" x1="82.196" y1="-17.513" x2="56.796" y2="-95.686"/>

</svg>

Thanks!

回答1:

I think your main problem is that some of the floats are being treated like strings in addition rather than numeric ids. I would also use the data() method in the odd place you weren't before.

So I would do things like the following to force numeracy, or you could use parseInt etc

var tmpPt = {
    x : +this.data("ox") + +dx,   
    y : +this.data("oy") + +dy
};

codepen

Added note: You may want to have a think about matrices and transformations as well as your drag is happening on elements that have a different screen transformation, so when you drag them, they move slightly quicker, so you may want to compensate for that.

来源：https://stackoverflow.com/questions/27073090/drag-along-path-snap-svg

标签

javascript

svg

raphael

snap.svg