In Hammer (Source), when I place a model into the map, it's completely black. Why is this, and how can I fix it?

Are you sure you are having just one window open? Sometimes if you handle two maps at a time, I get opengl to render not one of them right. It's the textures.

Just one open.

i had a similar issue cept the models were grey and patchy, the problem was the map was intirely indoor with only light and lightspot entities and the model was exposed to the sky with no light environment - as soon as i capped the room problem solved.

weird one but whats half-life without some wildly obscure errors

Remember that HL2 can do a half-assed RAD even if VIS cannot run. So if you're finding a lot of visual errors (you might be talking about in-editor...which could be many other things) then you most likely have a leak of some sort.

I've found this on today's update changelog:

Source SDK

* Added Snow and rain materials
* Made various improvements and fixes to .FGD files
* Fixed an issue in Vrad which was causing visible artifacts when lighting very large objects/areas
* Fixed the "cordon" texture used by Hammer

Will it help you at mapping?

Full Changelog (http://www.steampowered.com/index.php?area=news&id=403)

Here's a screenshot.

http://img213.exs.cx/img213/5813/blackprops6uz.jpg

Im sure there is an more accurate answer for this than I have, BUT:

From what I have experienced, it was always from the origin of the model being clipped into a world brush, or a solid-class entity (i.e. func_wall) therefore causing no light to hit the model. Your problem may be your origin is completely below the water line and causing this problem.

Half-Life 1:
I used to have a blacked out tank in a map and when I raised it and hit "drop to ground" the problem was solved. Why? the origin was below the ground and could not be lit.

Also, I had a tree model slightly below ground. Always black but I couldn't figure out why. I compiled and compiled until I saw that the ground solid was actually a func_wall. Took out the func_wall, and wah-la, a fully lit tree partially below the ground.

1 last thing: Ever notice that when your below the water in Charlie everthing is black? Why? Because that water is not tied to the entity func_water. Its only a water material because the textures water texture prefix "!" tells HL1 that its liquid. My gut instinct tells me you are experiencing the HL2 equivilent of this problem.

Whenever a water is tied to the actual func_water entity, you'll see transparency and/or movement (points to Escape, Saints & Sturm)(same mapper ;)) and also be able to see the outside world from below the surface. That Since I haven't tested putting an actual model half-way or more through a func_water, I can't tell you the results. This may or may not apply to HL2 in all cases, but the apple never falls far from the tree, if you take my meaning.

So, after that nice read I just gave you, Check your model to see if the origin is below the water. Raise it, test it.

If you have this problem in HL1, your model is either: Too far below ground but not far enough to disappear, --OR-- The origin is too far below a func_wall entity for Vis/Rad to render light on it.

It's like this regardless of (seemingly) everything.

Models will also go black if the solid world below them is null, even if there's a brush entity that has a normal texture above it, any model directly above will be pitch black. (Models get their light values from directly below their origin.)