The env_sprite entity is used to place, yep you guessed it, sprites in your level. It's also very easy to use. You just place the entity in the level where you want the sprite to be and then tell it what sprite you want. You can find a list of all the available sprites in the valve/sprites folder. To get rid of the black box around the sprite, set Render Mode either to glow or additive. Framerate is the number of frames per second. The default is 10. For spritename you type in the name of the sprite (sprites/spritename.spr). The other attributes and flags are pretty self explanatory. In my advanced lighting tutorial I talked about how to add halos around lights. You can use the env_sprite instead of the env_glow and get the same effect.
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