By subtracting the first distance (light to startShadow locator) from the second distance (light to endShadow locator), you get the difference between how far the locators are from the light source.
By subtracting the first distance (light to startShadow locator) from the second distance (light to endShadow locator), you get the difference between how far the locators are from the light source.
通过第二个距离（灯到结束阴影点）减去第一个距离（灯到开始阴影点），你得到从定位器间到光源处有多远距离。