Lighting effects

Most lighting effects in the Doom engine are set as a sector types, but it is also possible for linedef types to change a sector's lighting.

1: Flash
The sector's light is the brightness of the darkest connected sector and it will randomly flash at its defined brightness. If all connected sectors have the same or higher brightness than the flashing sector, the sector's light will not flash.

2: Slow strobe
The sector's light is the brightness of the darkest connected sector and it will flash at its defined brightness every 35 tics. If all connected sectors have the same or higher brightness than the flashing sector, a brightness of 0 is used for the "flash".

3: Fast strobe
The same as sector type 2, but it flashes every 15 tics.

4: Fast strobe, 20 damage
The same as sector type 3, but the sector's floor also causes 20 damage to the player every 32 tics.

8: Glow
The sector will glow between its brightness and the darkest connected sector's brightness. If all connected sectors have the same or higher brightness than the glowing sector, the sector's light will not glow.

In software rendering engines, the distance fading effect gives the sector's light the appearance of brightening away from the player and then darkening towards them; this effect becomes more pronounced the greater the difference between the brightness levels. Hardware rendering engines may handle this effect differently.

12: Slow strobe, synchronized
This is the same as sector type 2, but all sectors assigned this type will flash at the same time. This is useful when a level designer wants to have a lighting effect continue into multiple sectors, but the information about connected sectors' brightness still applies to synchronized types.

13: Fast strobe, synchronized
Like the above, this is the same as sector type 3, but all sectors assigned it will flash at the same time.

17: Fire flicker
The sector's lighting will be 16 brighter than its assigned value, and it will flicker to its assigned brightness randomly.

Linedef types
These linedef types directly affect a tagged sector's lighting. Note that while sectors can be given the brightest/darkest lighting from a connected sector, they will not be given that sector's type, so any effects will not be copied. For instance, when using type 12 to copy from a strobing sector, whichever brightness the strobe is at when the line is crossed will be applied to the tagged sector. Likewise the targeted sector will retain any lighting effect set for it after the change.

12: Change to brightest adjacent (W1)
Sets the tagged sector's brightness to the brightest connected sector when walked over. Despite being labeled "light turn on" in the source, it can also darken the target sector's light if it is already brighter than any connected sector.

13: Change to 255 brightness (W1)
Sets the tagged sector's brightness to 255 when walked over.

17: Start slow strobe (W1)
Makes the tagged sector strobe, as if sector type 2 had been set, when walked over.

35: Change to 35 brightness (W1)
Sets the tagged sector's brightness to 35 when walked over.

79: Change to 35 brightness (WR)
A repeatable copy of type 35.

80: Change to brightest adjacent (WR)
A repeatable copy of type 12.

81: Change to 255 brightness (WR)
A repeatable copy of type 13.

104: Change to darkest adjacent (W1)
Sets the tagged sector's brightness to the darkest connected sector when walked over. Unlike type 12, this will only work when there are darker connected sectors.

138: Change to 255 brightness (SR)
A copy of type 13 that is activated by a repeatable switch.

139: Change to 35 brightness (SR)
A copy of type 35 that is activated by a repeatable switch.