Linedef type 521

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Linedef type 521, Carry Objects on Floor (Accelerative), is a type of linedef special which carries Objects on any tagged sector's floor without scrolling the floor flat. Unlike linedef type 520, the speed can be changed in an accelerative/decelerative fashion.


The direction of the control linedef determines the direction the Objects will be carried. The length of the linedef indicates the base carrying speed (32 fracunits of length equal one fracunit per tic), however the actual effective carrying speed is set differently as explained ahead. The target sector must have the Conveyor Belt sector type applied to it, otherwise the carrying doesn't function properly.

On its own, this linedef will not carry Objects. Rather, the Objects will move whenever either the floor or ceiling of the control sector moves, which can done by using linedef executors. The actual carrying speed, in any given instant, is equal to the base speed × the distance the control sector has moved + the speed in the previous instant. In other words, every time the control sector's floor or ceiling rises, the carrier accelerates, and every time the floor or ceiling lowers, the carrier decelerates. If the floor and ceiling are returned to their original heights, the carrier will stop, and if they are lowered past this point, the carrier will accelerate in the reverse direction.

To keep things simple and easier to control, the best thing to do is just use a base speed of 1 fracunit per tic (by giving the control linedef a length of 32 fracunits), and control the carrying speed by moving the floor or ceiling of the control sector.

If used in conjunction with linedef type 401, the speed will instantly jump to a fixed value. If used in conjunction with linedef type 407, the speed will gradually increase or decrease.

If the Not Climbable flag is checked, the carrying effect is made exclusive – once an Object has been pushed by this effect, it cannot be pushed by any other pushing or carrying effect in the same tic. This is useful if the effect is applied to multiple adjacent sectors, since it would normally be applied twice when an Object crosses the border between two sectors with the effect. This flag should be checked when using the linedef special in conjunction with linedef type 64; otherwise the player will not stand still on the "moving sector".


Example WAD: ex_ld521_carryobjectsonfloor_accelerative.wad
  Linedef types – Scroll effects [view]
Wall scrolling:

Scroll Wall Front Side LeftScroll Wall Front Side RightScroll Wall According to LinedefScroll Wall According to Linedef (Accelerative)Scroll Wall According to Linedef (Displacement)Scroll Texture by Front Side OffsetsScroll Texture by Back Side Offsets

Plane scrolling:

Scroll Floor TextureScroll Floor Texture (Accelerative)Scroll Floor Texture (Displacement)Scroll Ceiling TextureScroll Ceiling Texture (Accelerative)Scroll Ceiling Texture (Displacement)Carry Objects on FloorCarry Objects on Floor (Accelerative)Carry Objects on Floor (Displacement)Carry Objects on CeilingCarry Objects on Ceiling (Accelerative)Carry Objects on Ceiling (Displacement)Scroll Floor Texture and Carry ObjectsScroll Floor Texture and Carry Objects (Accelerative)Scroll Floor Texture and Carry Objects (Displacement)Scroll Ceiling Texture and Carry ObjectsScroll Ceiling Texture and Carry Objects (Accelerative)Scroll Ceiling Texture and Carry Objects (Displacement)