code: private static void renderY(Graphic g, CollisionFunction function, CollisionRange range, int th, int x)
      {
          if (UtilMath.isBetween(x, range.getMinX(), range.getMaxX()))
          {
              g.drawRect(x, th - function.getRenderY(x) - 1, 0, 0, false);
          }
      }
docs: Render vertical collision from current vector.
  
  @param g The graphic buffer.
  @param function The collision function.
  @param range The collision range.
  @param th The tile height.
  @param x The current horizontal location.