Linedef type 251, Thwomp Block, is a type of floor over floor block which behaves like the Thwomp enemy from the Mario games. If the player gets too close, it will fall and attempt to crush them. It will then rise back to its original position, during which the player can use the FOF as an elevator. This linedef type is used in Pipe Towers Zone.
Setup
The flats, floor height, and ceiling height of the FOF are determined by the flats, floor height, and ceiling height of the control sector. The control linedef's middle texture is used as the Thwomp's "resting" face only until it falls for the first time, after it the linedef's lower texture is used instead for the effect. The linedef's upper texture is used as the Thwomp's "falling" face. After the Thwomp has fallen, it reverts back to its previous texture. You don't need to specify the height at which the Thwomp will stop falling; it automatically stops when it reaches the sector floor.
The light level of the control sector will determine the brightness of the shadow cast by the FOF. If the light level of the control sector is lower than that of the target sector, then it will cast a dark shadow. If the light level of the control sector is higher than that of the target sector, then the FOF will illuminate the area below it. If the light level of the control sector is equal to that of the target sector, then the FOF will not affect the light of the area below it.
Additionally, if Flag [9] / Solid Midtexture / Effect 4 is checked, it is possible to customize the block's "crushing" sound (the linedef's front X offset indicates the sound number). If Flag [10] / Repeat Midtexture / Effect 5 is checked, it is also possible to customize the block's speed when falling and rising using the linedef's Y and X distances, respectively. One fracunit of length equal 0.125 fracunits per tic. The default speeds for the falling and rising are 10 fracunits per tic (80 fracunits of length) and 2 fracunits per tic (16 fracunits of length), respectively.
Linedef special info
Floor height
Height of bottom of FOF
Ceiling height
Height of top of FOF
Sector light level
Brightness of shadow cast
Linedef X distance
Custom rising speed (1 FU/8 tics per FU length) (if [10] Repeat Midtexture / Effect 5 is checked)
Linedef Y distance
Custom falling speed (1 FU/8 tics per FU length) (if [10] Repeat Midtexture / Effect 5 is checked)
Front upper texture
Thwomp "falling" face
Front middle texture
Thwomp "resting" face (only until first fall)
Front lower texture
Thwomp "resting" face (after first fall)
Front texture X offset
Custom crushing sound number (if [9] Solid Midtexture / Effect 4 is checked)
Linedef flags
[9] Solid Midtexture / Effect 4: Crushing sound can be customized [10] Repeat Midtexture / Effect 5: Falling/rising speed can be customized
In general, you should use the same dimensions and textures as the Thwomp blocks in Pipe Towers Zone. Aside from possible use as generic crushers, this type of FOF too highly specialized for a lot of experimentation, so even a slightly different usage might not turn out well.
