Problem with Depth test

recently,I create a mesh object,but when I enable the lighting,there are some ‘holes’ on my object,then I try some matheds to solve it,
I found when I enable the Depth test with GL_LESS,the hole disapeared,any body who can tell me why,does the hole really exist??

GL_LESS is the default paramater when enabling depth test. It simply says that what’s nearest of the view point will be shown whereas what’s farest will be ignored.
If you don’t use depth test, you’ll have to do that work yourself. So, with ensuring you draw with the ‘painter algorithm’: draw what’s far first, then what’s near last.

Hope that helps.

test my first reply.