I hope I get an answer to this one .
I have a water stream that travels downward over steps and I was wondering if there was anyway to detect at what camera.z's height has to be for the portal to reflect properly.

If I just have the standard code (view.z = 2*view.portal_z - camera.z) the block entities in my level down't show up when shaders are applied to them.
(Yes I excluded the NOSHADER flag).

But they do show in the reflection if I exclude the NOPORTAL or I move the level either up or down in WED.
Excludeing the NOPORTALCLIP option is no good as when I am in the third person view the reflections are horrible.
So is there anyway of doing this with maybe a c_scan or c_trace to set camera.z properly.
Any help would be greatly appreciated.

Anybody, Or can't it be done.

The clipping plane in HLSL is in clip space not world space. You must either write you own clipping algorithm in every HLSL-Shader that needs clipping, or you must use the NOSHADER flag in the view (yes i know, this is no option...)

And in a river ... ther is no defined "plane" for refelctions. For the river i would unly use environment mapping.

Bit of a pain but oh well I like the effect I got in my stream so I guees I'll have to go with what I have achieved thus far.

Thanks for the info and tips wdlmaster I will go with your advice.