/**
    * Get the effect the light should apply to a given location
    *
    * @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(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);
      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};
      }
   }