物件的边缘高亮(Entity edge highlight)

原文出处：http://www.cppblog.com/lai3d/archive/2007/11/18/36899.html

在游戏里面鼠标与某个npc相交了后，就让npc的边缘高亮显示或者怎么处理下，让玩家很明确地知道他点下去就能选中此npc。《卓越之剑》有这效果。google了下没找到相关资料。

我在gamedev上的提问：
when the cursor is over an entity, I want to highlight it's edge so that a player can immediately know he can pick this entity after he click the mouse left button. for example, there are many monsters around the main character in the game, it is not easy to pick one monster. I googled this, but found nothing. who can give me some suggestion?

老外的回答：
The simplest method is to draw the object colored in the highlight color, with some scaling to make it larger than the original object. Do this drawing with depth writes turned off. Then, after this, draw the object as usual, with depth writes on again. There are more complex methods, depending on your application - depending on what is your bottleneck, depending on complexity of your monster models etc etc. but the method above is simple to implement and should work for most cases.