Env_Skypaint is a recently added (with release of GMod 13 :L) entity that’s used to make dynamic skyboxes.
With it, you can easily edit your sky’s colors, add moving clouds or stars (or any texture you want, such as cats) - all in real time.
If you’re also experienced with Lua and color correction, you can even make day-night cycles.
Setting up the Hammer - Skip if you have garrysmod.fgd mounted already.
The entity is exclusive to Garry’s Mod, don’t expect to be able to use it in other games.
1. Launch Hammer, find a Tools tab, and press the Options… button.
2. You should see this window. In the second box that says “Game Data files”, press Add and locate the garrysmod.fgd file.
The path is “C:\Program Files (x86)\Steam\steamapps\common\GarrysMod\garrysmod” for 64-bit Windows.
In case you hate finding files, you can download the file here.
3. Restart your Hammer, and the entities should be in here. You can try it by loading a map and making an env_skypaint entity.
Using the entity in Hammer
1. Make / Load a map of your liking.
2. Create an entity, and select “env_skypaint”.
3. An entity with those properties should be created.
4. Now, press the Map button on your upper tab, go to Map Properties… and change the SkyBox Texture Name parameter to “painted”.
5. Compile your map and load it in Garry’s Mod with Sandbox gamemode selected.
Configuring the Skypaint entity
1. The best part is here! Using a Q menu, spawn the Sky Editor somewhere in your map.
NOTE Also, your skybox should look like this by default.
2. Close the Q menu and press a C key. With the cursor, right click on the Sky Editor and you’re ready to edit its properties.
To prevent the window from closing when unpressing C, just click at some of the textboxes. It’ll lock itself.
3. Once done tweaking your values, copy the properties to your Hammer manually (as in rewriting them into your env_skypaint).
NOTE Since env_skypaint isn’t related to VRAD at all, you’ll need to make your own lighting settings for your skybox inside Hammer.
NOTE Use the Sun Editor entity to orientate the sun.
Converting the colors from 255 to 0.00 - 1.00
The colors aren’t in RGB “255 255 255” format. In order to convert them to these values, you’ll need to get your color value (such as 200 and divide it by 255, resulting in 0.78 rounded for the red color field)