That code is already in DECORATE, but I think that is only for when it is in Idle as it is only in the Spawn section.
I think I found out where the jumping comes in though in the code.
Code:
Missile:
MNTR V 0 A_Jump (82,20)
MNTR V 0 A_Jump (32,9)
SPI2 U 5 A_Facetarget
TNT1 A 0 A_jumpifcloser(1024,6)
SPI2 E 0 A_Facetarget
MNTR E 0 A_Playsound ("spider/step")
SPI2 U 50 A_Skullattack
MNTR A 0 A_Playsound ("spider/land")
SPI2 A 1 A_stop
goto see
SPI2 U 5 A_Facetarget
SPI2 X 2 A_custommissile("flameshot", 54, 0, -8, 0)
SPI2 X 2 A_custommissile("flameshot", 54, 0, 0, 0)
SPI2 X 2 A_custommissile("flameshot", 54, 0, 8, 0)
SPI2 X 3 A_Facetarget
I am not sure about this, but judging from the first two lines (jumping) and the (Skullattack) I assume that this is the Jumping attack, where the spider is supposed to jump in the air towards the player. This is when it "glides" across the ground instead of actually jumping in the air.
Perhaps change the (Skullattack) with a thing thrust towards the player? Though I am not sure if that would still do damage or not.
Is this correct? If so, how would one change this part of the code to actually make the spider jump when it uses this attack?
PS: I have tested this enemy in a room with the ceiling ridiculously high and it still does not jump.