Very Thin triangles hides/seek

I have a peculiar rendering problem while rendering a very thin triangle, that too only in zoomed out display. The triangles are
at the back of some opaque object and it sometimes get display and sometimes not during zooming in operation. When I zoomed in to a certain extent, then the triangles are get hidden properly and also it is hidden properly when i switch to LINE mode. I think the opengl doesn’t handle very thin object FILL shading during rasterization. Bu t what I don’t understand is that why the depth buffer for that polygon is not computed properly as it comes in front of opaque object and goes back during zooming in.

Anyone knows this problem, please tell me how to avoid this.

Try narrowing your viewing volume, so the z-buffer values are more accurate.
(they are integers relative to the viewing volume and their accurancy is determined by the distance between front & back clipping plane)

You can do this where you set your clipping planes in ‘gluPerspective()’ or ‘glFrustrum()’: Try to make the distance between the front & back clipping plane smaller.

This could be one thing