Maths Formula for how sigma.js create view

Question

I am having very hard time understanding sigmas.js , how it works . Interested to know science behind the seen .

Reading library I understood that it renders vertices and edges on canvas .

It has an amazing code which resales the coordinate based on number of vertices and edges of graph to show all nodes .

What is maths for calculating view at applyview method https://github.com/jacomyal/sigma.js/blob/master/src/classes/sigma.classes.camera.js#L89

How apply view works :

sigma.classes.camera.prototype.applyView = function(read, write, options) {
    options = options || {};
    write = write !== undefined ? write : this.prefix;
    read = read !== undefined ? read : this.readPrefix;

    var nodes = options.nodes || this.graph.nodes(),
        edges = options.edges || this.graph.edges();

    var i,
        l,
        node,
        relCos = Math.cos(this.angle) / this.ratio,
        relSin = Math.sin(this.angle) / this.ratio,
        nodeRatio = Math.pow(this.ratio, this.settings('nodesPowRatio')),
        edgeRatio = Math.pow(this.ratio, this.settings('edgesPowRatio')),
        xOffset = (options.width || 0) / 2 - this.x * relCos - this.y * relSin,
        yOffset = (options.height || 0) / 2 - this.y * relCos + this.x * relSin;

    for (i = 0, l = nodes.length; i < l; i++) {
      node = nodes[i];
      node[write + 'x'] =
        (node[read + 'x'] || 0) * relCos +
        (node[read + 'y'] || 0) * relSin +
        xOffset;
      node[write + 'y'] =
        (node[read + 'y'] || 0) * relCos -
        (node[read + 'x'] || 0) * relSin +
        yOffset;
      node[write + 'size'] =
        (node[read + 'size'] || 0) /
        nodeRatio;
    }

    for (i = 0, l = edges.length; i < l; i++) {
      edges[i][write + 'size'] =
        (edges[i][read + 'size'] || 0) /
        edgeRatio;
    }

    return this;
  };