Transparent objects

If I wanted a solid brush to let light through it, for example a solid window texture that I wanted to let light in. How would I go about it?

I think you can make it a func_detail and then set it to not cast lightmap shadows.

[editline]05:43PM[/editline]

func_brush, sorry.

Make it func_brush. It has a keyvalue where you can choose whether it casts lightmap shadows or not.