HyperbolicDistance.js

function dist(x, y) {
  return Math.sqrt(Math.pow(y[0]-x[0], 2)+Math.pow(y[1]-x[1], 2));
}
function ln(x) {
  return Math.log(x);
}
function abs(x) {
  return Math.abs(x);
}
function disth(p, q) {
  if(p[0] == q[0]) {
    var za = [p[0], 0];
    return abs(ln(dist(za, q)/dist(za, p)));
  }
  else {
    var c = [0, 0];
    if(q[1] != p[1]) {
      c[0] = ((0-((p[1]+q[1])/2)) / ((p[0]-q[0])/(q[1]-p[1]))) + ((p[0]+q[0])/2);
    }
    else {
      c[0] = (p[0]+q[0])/2;
    }
    var r = dist(c, p);
    var zL = [c[0]-r, 0];
    var zR = [c[0]+r, 0];
    return abs(ln((dist(zL, q)*dist(p,zR))/(dist(zL, p)*dist(q,zR))));
  }
}
function distGrid(c, size, res) {
  var grid = [];
  for(var i=-size/2; i<=size/2; i += res) {
    grid.unshift([]);
    for(var j=-size/2; j<=size/2; j += res) {
      var point = [c[0]+j, c[1]+i];
      if(point[1] <= 0) {
        grid[0].push(-1);
      }
      else {
        grid[0].push(disth(c, point));
      }
    }
  }
  return grid;
}
function radGrid(c, r, size, res) {
  var grid = distGrid(c, size, res);
  for(var i=0; i<grid.length; ++i) {
    for(var j=0; j<grid[i].length; ++j) {
      if(grid[i][j] != -1) {
        grid[i][j] = abs(grid[i][j]-r);
      }
    }
  }
  return grid;
}
function prettyPrintRadGrid(c, r, size, res, thresh) {
  var grid = radGrid(c, r, size, res);
  var wholeMsg = "";
  for(var i=0; i<grid.length; ++i) {
    var lineMsg = "";
    for(var j=0; j<grid.length; ++j) {
      var msg = String(grid[i][j]).slice(0, 5);
      while(msg.length <= 5) {
        msg = " " + msg;
      }
      if(grid[i][j] < thresh && grid[i][j] != -1) {
        msg = "\u2588\u2588\u2588\u2588\u2588";
      }
      msg = msg + ",";
      lineMsg += msg;
    }
    wholeMsg += lineMsg.slice(0, lineMsg.length-1);
    wholeMsg += "\n";
  }
  console.log(wholeMsg);
}