I'm trying to make an area of my map particularly foggy, so I've settled on using func_smokevolume so achieve this goal. I put it in my map, and it looks great except that it's really dark. I've set particle color 1 and 2 to very light colors, but it still looks like smoke rather than fog. I'm using particle_smokegrenade for the material, should I switch this to something else? if so, what would look good for some creepy fog?