RandomHelpers.js

function RandPoints(n, maxx, maxy, minx, miny)
{
    let points = new Array(n)
    for (let i = 0; i < n; i++)
    {
        let x = RandomNumber(minx, maxx)
        let y = RandomNumber(miny, maxy)
        points[i] = {x: x, y: y}
    }

    return points
}

function RandomNumber(min, max) { // min and max included 
    return Math.random() * (max - min + 1) + min
}
  
// line intercept math by Paul Bourke http://paulbourke.net/geometry/pointlineplane/
// Determine the intersection point of two line segments
// Return FALSE if the lines don't intersect
function intersect(x1, y1, x2, y2, x3, y3, x4, y4) {

    // Check if none of the lines are of length 0
      if ((x1 === x2 && y1 === y2) || (x3 === x4 && y3 === y4)) {
          return false
      }
  
      denominator = ((y4 - y3) * (x2 - x1) - (x4 - x3) * (y2 - y1))
  
    // Lines are parallel
      if (denominator === 0) {
          return false
      }
  
      let ua = ((x4 - x3) * (y1 - y3) - (y4 - y3) * (x1 - x3)) / denominator
      let ub = ((x2 - x1) * (y1 - y3) - (y2 - y1) * (x1 - x3)) / denominator
  
    // is the intersection along the segments
      if (ua <= 0 || ua >= 1 || ub <= 0 || ub >= 1) {
          return false
      }
  
    // Return a object with the x and y coordinates of the intersection
      let x = x1 + ua * (x2 - x1)
      let y = y1 + ua * (y2 - y1)
  
      return {x, y}
  }

  function randItem(items)
  {
      return items[Math.floor(Math.random()*items.length)]
  }

  function select(id, filter) { 
      filter = filter || ""
      return "[id = \"" + id.replace('.', '\.') + "\" " + filter + " ]"
}

function shadeColor(color, percent) {

    var R = parseInt(color.substring(1,3),16);
    var G = parseInt(color.substring(3,5),16);
    var B = parseInt(color.substring(5,7),16);

    R = parseInt(R * (100 + percent) / 100);
    G = parseInt(G * (100 + percent) / 100);
    B = parseInt(B * (100 + percent) / 100);

    R = (R<255)?R:255;  
    G = (G<255)?G:255;  
    B = (B<255)?B:255;  

    var RR = ((R.toString(16).length==1)?"0"+R.toString(16):R.toString(16));
    var GG = ((G.toString(16).length==1)?"0"+G.toString(16):G.toString(16));
    var BB = ((B.toString(16).length==1)?"0"+B.toString(16):B.toString(16));

    return "#"+RR+GG+BB;
}