From Valve Developer Community
- Start Fade Dist (fademindist)
- Distance at which the prop starts to fade.
- End Fade Dist (fademaxdist)
- Max fade distance at which the prop is visible.
- If start fade is <0, the prop will disappear instantly when end fade is hit.
- If end fade is <0, the prop won't disappear at all. (This is the default behaviour.)
- The values will scale appropriately if the prop is in a 3D Skybox.
- Fade Scale (fadescale)
- If you specify so in worldspawn, or if the engine is running below DirectX 8 (DX7 in Ep1), props will fade out even if the fade distances above aren't specified. This value gives you some control over when this happens: numbers smaller than 1 cause the prop to fade out at further distances, and greater than 1 cause it to fade out at closer distances. Using 0 turns off the forced fade altogether. See also the QC command $noforcedfade.