broken shadows, help

Have you got a leak somewhere?

Open your vmf file in the SDK and go to Map > Load pointfile and it might show some crazy red lines flying around all over the place. These represent leaks which often break the map completely, but can cause strange lighting issues as well.

If it opens a file browser after trying to load pointfile, hammer hasn't found the file so you won't have any leaks.

Leaks can be caused by model entities which are partially out of your skybox in "the void", as well as through displacements and mismatched areaportals if you've experimented with any optimisation yet.

I had this error once when i used the wrong light entities. Could you make a screenshot of Hammer where you are showing the options of one of your light entities?

One of your light entities has "Appearance" setting changed. It is a known bug in CS:GO SDK, if you change "Apperance" setting to anything else other than default it would cause broken shadows.

For those who don't know, "Appearance" setting is used to change how light flickers ETC.

Nope, one of the trade-offs with lighting in CSGO is that there are no toggleable (or flickering, etc) light sources.

Quote from Baggle!

yes, this fixed it, i had i light that was flickering. thanks for your help. but is there a way to have flickering or pulsing lighting in csgo that dosent have this effect?

Unfortunately, as Spence mentioned, you can't have toggle-able lights (named) or with special effects (strobe, flicker, etc) in CSGO HDR lighting otherwise you'll end up with this black patch as you have experienced.

A simple workaround is to have a glow sprite near the light source to which you can apply special effects without CSGO going berserk.