return absolute x,y position of each node

[brucejcw]

Is there any API can return absolute x,y position of each node? I couldn't find it in layout

var layout = new Springy.Layout.ForceDirected(
  graph,
  400.0, // Spring stiffness
  400.0, // Node repulsion
  0.5 // Damping
);

[dhotson]

I'd suggest looking at the layout.eachNode function. Usage looks something like this:

layout.eachNode(function(node, point) {
  console.log(node); // Original graph node
  // The "point" is what the layout uses to track position/velocity/mass of a node
  console.log(point.p.x); 
  console.log(point.p.y);
});

Point properties:

springy/springy.js

Lines 611 to 617 in 559a400

	// Point
	Layout.ForceDirected.Point = function(position, mass) {
	this.p = position; // position
	this.m = mass; // mass
	this.v = new Vector(0, 0); // velocity
	this.a = new Vector(0, 0); // acceleration
	};

Also, I usually transform the underlying "world" coordinates to screen coordinates separately to the layout algorithm.

e.g. here's how it's done in springyui.js:

springy/springyui.js

Lines 63 to 69 in 559a400

	// convert to/from screen coordinates
	var toScreen = function(p) {
	var size = currentBB.topright.subtract(currentBB.bottomleft);
	var sx = p.subtract(currentBB.bottomleft).divide(size.x).x * canvas.width;
	var sy = p.subtract(currentBB.bottomleft).divide(size.y).y * canvas.height;
	return new Springy.Vector(sx, sy);
	};

[brucejcw]

That's so kind of you. thanks, let me try first

[brucejcw]

@dhotson Does the springyui.js depends on springy.js? I didn't found Graph definition in springyui.js

[dhotson]

Yep, that's right—you need to include springy.js first.

[brucejcw]

hi, dhotson, I've tried to using your toScreen algorithm, but seems the screen x,y not looks like the point one.

toScreen = (p)->
    size = currentBB.topright.subtract(currentBB.bottomleft);
    sx = p.subtract(currentBB.bottomleft).divide(size.x).x * 1000;
    sy = p.subtract(currentBB.bottomleft).divide(size.y).y * 1000;
    return new Springy.Vector(sx, sy);
layout = new Springy.Layout.ForceDirected graph, 1000, 1000
currentBB = layout.getBoundingBox();
j = 0
layout.eachNode (node, point)->
    console.log node, point
    list[j].position = toScreen point.p
    console.log list[j].position
    j++
<canvas id="my_canvas" width="1000" height="1000" />

[dhotson]

Hey sorry, I'm not quite sure I'm following what you mean—what are you expecting to see here?

[brucejcw]

Ok, I may not explain well.
The screenshot shows two graphs, one is springy, the other one is html div
and the absolute position of each div is using toScreen method which picked from springyui.js.
see

What I mean is I'm converting canvas coordinate to window's using toScreen method, but the result shows the two graphs are not the same