Irrlicht Engine

i try some example like quake3map but i found that the wall is too sharp,is there any function to make the wall isn't sharp like that in irrlicht,

I think what you want is anti-aliasing (FSAA).
I think you cannot ask for it using Irrlicht, so I suspect it will be up to the user to enable it in his ATi/nVidia/WhatEver(TM) control panel.

Well, maybe it would a good to suggest future implementation of FSAA into the Irrlicht engine. It would be useful.