Grr. Separate caching wasn't redundant. After a mage player uses the cloth, the handsOn() allows them to adjust the slider to an inappropriate speed before casting levitate.

Not an obvious exploit or a dangerous one. It'd just cause hero to outpace the tentacle and get it stuck in an edge case.

Fixed. The patch sets its own speed for crossing after handsOff().

Caching takes place when the cloth is used.
If the speed slider is adjusted between then and Levitate, the new value will be discarded.
After crossing, hero's speed will be whatever it was when the cloth was used.

*sigh* Bytes were available,..

Caching takes place when the cloth is used AND just before crossing.
If the speed slider is adjusted between using the cloth and Levitate, the new value will be preserved.
After crossing, hero's speed will be whatever was last cached.

Technically if the slider is adjusted between using the cloth and an abort... the second cache in state 5 is skipped, and the new value will be discarded, restoring the original speed instead.

I think I've sharpened that edge case enough. =)

@bluegr:

// Mages have no other script to levitate across from left to right.

Are you sure about this statement?

Yes.

Vertical levitation scripts exist, but they do not carry hero across from left to right. With those, hero levitates down to the pit floor, manually walks to the other side, then levitates up via a separate casting.

From the wiki

• In the opening of the game, Levitate is used, along with the Sheet, to cross the pit leading out of the Dark One's Cave.

Fighters and rogues each have a second script (crossByHandLeft, tightRopeLeft) to travel *horizontally* over the pit in the opposite direction, from the left side.

Mages do not.

• hero::doVerb(cloth) explicitly requires standing on the upper right side before it schedules sLevitateOverPit.
• sLevitateOverPit is a requirement for the Levitate spell to set "register" and cue the script.
• sLevitateOverPit::changeState(4) advances to state 5 if register == 1.
  • Otherwise, it skips to an abort state (8).
• sLevitateOverPit::changeState(5) travels leftward when register == 1.
  • If state 5 were somehow reached with register == 0, it would go right. State 4 never allows this.
• I've quoted some of that code over at the ticket.

When sLevitateOverPit starts, it advances through states 0-3 then does handsOn().
State 4 does handsOff() and cleans up after state 3. It is a necessary step.

script 710 - sLevitateOverPit::changeState()

(3
	3
	(g0_hero cycleSpeed: local2 setLoop: 1 1 setCycle: Fwd)
	# Add sLevitateOverPit to EventHandler Lists.
	(g72_keyDownHandler addToFront: self)
	(g73_mouseDownHandler addToFront: self)
	(global1 handsOn:)
)
(4
	4
	(g1_Glory handsOff:)
	(g72_keyDownHandler delete: self)
	(g73_mouseDownHandler delete: self)
	(if register (= cycles 1) else (self changeState: 8))
)

So skipping directly to state 5 with register=0 set for rightward movement (from the left side) should never happen.

script 710 - sLevitateOverPit::handleEvent()

(method (handleEvent param1)
	(if
	(and (== state 3) (proc64999_5 (param1 type?) 4 32 1))
		(if (== (param1 message?) 89)
			# 89 is a message from Levitate. More on that later.
			(= register 1)
		else
			(= register 0)
		)
		(self cue:)
		(param1 claimed: 1)
		(return)
	else
		(super handleEvent: param1)
	)
)

sLevitateOverPit only responds to events in state 3, when the cloth has been unfurled.
It checks for Levitate's 89 message, setting register=1, so state 4 will advance and cause leftward movement.
Any other event sets register=0, causing state 4 to abort.

@bluegr

There are about 4-5 places where levitate can be used
[...]
Are you sure that this patch won’t affect these locations?

Levitate delegates its effects to scripts within each room.
Modifying one room's Levitate effect will not affect any other locations.

Room 710 does schedule other levitation scripts, distinct from the horizontal crossing.
Modifying sLevitateOverPit will not affect them either.

From the wiki

• After returning to the Dark One's Cave with the Rituals, Levitate will get the Hero down to the bottom of the pit to where the Pit Horror is, as well as up the other side.

script 21 - levitateSpell::doVerb(4)

(cond 
	((or (== g11_myCurrentRoomNum 750) (== g11_myCurrentRoomNum 340))
			(g2_myCurrentRoom notify: 89)
	)
	(
		(and
			(== g11_myCurrentRoomNum 710)
			(== (g0_hero script?) (ScriptID 710 1))  # sLevitateOverPit
			(== ((g0_hero script?) state?) 3)
		)
		((g0_hero script?) register: 1)
		((g0_hero script?) cue:)
		# Cross leftward horizontally.
	)
	((super doVerb: 4)  # Spells ask super if spellcasting is possible.
		(if
			# Test if param1 is found among candidates param2 ... paramN.
			(proc64999_5
				g11_myCurrentRoomNum
				# Lots of room numbers...
				710
				# Lots of room numbers...
			)
			((= temp0 (Event new:)) type: 1 message: 89)
			(if (not (g73_mouseDownHandler handleEvent: temp0))
				(g6_regions handleEvent: temp0)
			)
			(temp0 dispose:)
			(return 1)
		else
			# Show one of these messsages.
			#   "This isn't a good place to use that spell."
			#   "This is definitely not an appropriate time
			#     to cast your Levitate spell."
			#   "Now is not a good time to cast your Levitate spell."
# ...
		)
	)
	(else (return 1))
)

If not specifically using the cloth to float leftward, g73_mouseDownHandler and g6_regions get sent event 89.

regions is an EventHandler List with one element, rm710. (ancestry: Rgn/Room/GloryRm)
In script 64994, Rgn::handleEvent() translates that to rm710::doVerb(89).

script 710 - rm710::doVerb(89)

(cond 
	((proc0_4 101)  # Test an endgame plot flag set at the castle gate (600) or cave entrance (790).
		(cond 
			((and (> (g0_hero x?) 190) (< (g0_hero y?) 125))    # Standing at upper right.
				(g2_myCurrentRoom setScript: (ScriptID 711 4))  # sLeviDownRt
			)
			((and (< (g0_hero x?) 190) (< (g0_hero y?) 125))    # Standing at upper left.
				(g2_myCurrentRoom setScript: (ScriptID 711 2))  # sLeviDown
			)
			((and (not (< (global0 y?) 125)) (> (global0 x?) 160))  # Standing at lower right.
				(g2_myCurrentRoom setScript: (ScriptID 711 5))      # sLeviUpRt
			)
			(else                                               # Standing at lower left
				(global2 setScript: (ScriptID 711 3))  # sLeviUp
			)
		)
	)
	((and (> (global0 x?) 190) (< (global0 y?) 125))  # Start of game, standing at upper right.
		# leviCode, generic hover, walking to (222,45) first.
		((ScriptID 31 0) init: 222 45 30 0 2)
	)
	(else                                             # Start of game, standing at upper left.
		# leviCode, generic hover, walking to (119,79) first.
		((ScriptID 31 0) init: 119 79 35 0 2)
	)
)

None of those scripts reference sLevitateOverPit. They send hero up and down independently.

I've added instructions in the OP to test the room under endgame conditions - when the pit floor is accessible, along with all those other vertical Levitate effects.

Great work, well done! :)

Merging