gistfile1.js

// handle click events on the canvas
function canvasClick(e) 
{
  var x;
  var y;
  
  // grab html page coords
  if (e.pageX != undefined && e.pageY != undefined) 
  {
    x = e.pageX;
    y = e.pageY;
  }
  else 
  {
    x = e.clientX + document.body.scrollLeft +
      document.documentElement.scrollLeft;
    y = e.clientY + document.body.scrollTop +
      document.documentElement.scrollTop;
  }
  
  // make them relative to the canvas only
  x -= canvas.offsetLeft;
  y -= canvas.offsetTop;
  
  // return tile x,y that we clicked
  var cell = 
      [
        Math.floor(x/tileWidth),
        Math.floor(y/tileHeight)
      ];
  
  // now we know while tile we clicked
  console.log('we clicked tile '+cell[0]+','+cell[1]);
  
  pathStart = pathEnd;
  pathEnd = cell;
  
  // calculate path
  currentPath = findPath(world,pathStart,pathEnd);
  redraw();
}