Shoot-Through Railings Created 4 years ago2019-12-21 12:45:37 UTC by _Vissova_

How do I create railings and catwalks that are solid but can be shot through? I decompiled a Half-Life map to see how Valve set up railings you can shoot through but they seem to just be func_illusionary brushes with no special settings and no extra clip brushes. I assume this is because of the decompiler and there is actually more to it?

If you're using an alpha-tested texture (file name starts with "~" and it typically have blue areas in it), just tie the visible brush to a func_illusionary with the "Solid" render mode and add a clip brush in the same place. Clip brushes are not included in decompiled maps because they are technically not part of the compiled map.

Oohh I understand. I didn't realize you could shoot through clip brushes, I thought they blocked everything. Thank you!

Yes clip brushes are colliders for player and monster models.
Bullets pass right through

There's a shortcut to it assuming that you use the latest VHLT: create a clip brush, paint the sides of it you want with the desired texture, tie this brush to func_wall, set Render Mode to Solid, FX Amount to 255. now you don't need an extra clip brush over it, which makes editing much more convenient.
P.S. Keep in mind that certain tool textures can conflict with the CLIP texture, so if you get any errors mentioning the brush then check if it has any tool textures other than CLIP applied anywhere.

CLIP brushes are part of the compiled map it's just that visible geometry and player collision geometry are separate and decompilers can't tell apart from CLIP generated from ordinary brushes and CLIP brushes