I called glPolygonOffset like this:
First I drew quads with PolgyonMode set to GL_FILL, enable GL_POLYGON_OFFSET_FILL, and everything is ok, the wireframe of the quads were displayed correctly on the screen.
To draw the points, with the same offset setting, I tried to enable GL_POLYGON_OFFSET_FILL, GL_POLYGON_OFFSET_LINE, GL_POLYGON_OFFSET_POINT, but none of them worked.
I searched on google but didn't find the answer. I am thinking that whether point and line are not polygon in GL, so they are not affected by glPolygonOffset? If they were polygon, which type should I use, GL_POLYGON_OFFSET_FILL or GL_POLYGON_OFFSET_POINT?