/**
    * Get the effect the light should apply to a given location
    *
    * @param map The tile map you're lighting (I'm assuming you've got something)
    * @param x The x coordinate of the location being considered for lighting
    * @param y The y coordinate of the location being considered for lighting
    * @param colouredLights True if we're supporting coloured lights
    *
    * @return The effect on a given location of the light in terms of colour components (all
    * the same if we don't support coloured lights)
    */
   public float[] getEffectAt(Map map, float x, float y, boolean colouredLights) {
      // first work out what propotion of the strength distance the light
      // is from the point. This is a value from 0-1 where 1 is the centre of the
      // light (i.e. full brightness) and 0 is the very edge (or outside) the lights
      // range
      float dx = (x - xpos);
      float dy = (y - ypos);

      // first work out how many steps along the line we're going to do
      // should really work out the distance here, but a Math.sqrt() is probably pretty expensive
      int steps = (int) ((Math.abs(dx) + Math.abs(dy)) * 4);

      // now work out how far on each move we want to go (using minus dx/dy here since the previous calculations worked it out
      // in the wrong direction)
      float stepX = (-dx / steps);
      float stepY = (-dy / steps);

      // start at the position of the light
      float px = x;
      float py = y;

      // move across the map checking the points
      for (int i=0;i<steps-1;i++) {
            if (map.blocked((int) px, (int) py)) {
                  return 0;
            }

           // move to the next point
           px += stepX;
           py += stepY;
      }

      // once we reach this point we know the light isn't blocked

      // calculate the brightness
      float distance2 = (dx*dx)+(dy*dy);
      float effect = 1 - (distance2 / (strength*strength));

      if (effect < 0) {
         effect = 0;
      }

      // if we doing coloured lights then multiple the colour of the light
      // by the effect. Otherwise just use the effect for all components to
      // give white light
      if (colouredLights) {
         return new float[] {col.r * effect, col.g * effect, col.b * effect};
      } else {
         return new float[] {effect,effect,effect};
      }
   }