CV2 Floor drop stuff

If you have any questions about what I mean, or things that aren't written here, send a twitch PM to ZBrannigan. If you don't know how, you can send one by following this link, I believe: http://www.twitch.tv/message/compose?to=ZBrannigan


Table of Contents:
>General notes
>How I think floor drops work (conjecture)
>New Drops
>-Start of the game
>-Holy water
>-Camilla's mansion
>-Crazy one that you probably shouldn't do
>-Whip-Only Nail Mansion Drop
>Old drops
>-After farming skeletons (towards blue crystal town)
>-In the chain whip room
>-Both after getting blue crystal
>-Heart Mansion
>-Rib Mansion
>-Death's Mansion
>-Morning star room
>-Camilla's Mansion (just before laurels guy)
>-Dracula's Mansion
>Recovery strategies (for common mistakes at least)
>To do list/things I haven't found out yet
>General information about the subpixel (the address is in the general notes just below)
>Extra info about recovering from missing floor drops in general


General notes about floor drops:
-To do a floor drop, you walk off an edge, and whip on the first frame that you start falling (i.e. the first frame that, if you whip on it, you will still fall). You can tell if you whip on the right frame if, when you start falling, simon's sprite is spliced in a weird way where his body looks like he's standing and the back of him is his arm looking like he's whipping.
-Floor drops rely on your y-subpixel, which changes almost any time your y-velocity is nonzero (does not change when you're falling at terminal velocity even if you whip)
-Your y-subpixel is set to 00 if you climb stairs or die. Otherwise it is persistent (across screen transitions, entering buildings, etc.)
-If you accidentally jump on flat ground (i.e. land on the same level as you jumped from), jump again on flat ground and the y-subpixel will be back to what it was before you jumped the first time
-If you do a whip-jump at any time, the y-subpixel will be unpredictable
-For any most floor drops, you have a 3/32 chance of getting it without a setup, but you can fall down without trying the drop and jump up again a certain number of times to increase the chances. More explanation at the end of this.
-I have almost no explanation as to why, but you are able to throw a holy water (or probably use any other item) while you are still doing your whip animation, if you get the right frame for your floor drop, and then you will not be able to fall through the floor.
-Anyone who wants to go look at the y-subpixel closer can open up an emulator (at least for BizHawk) and look at the memory address 0336 in the RAM (in the built-in hex editor, not an external one). The correct y-subpixels are 00, 08, and 10 for almost every floor drop, but for a few cases, Simon's y position on the screen matters.
-The y-subpixel will never be a number that isn't N0 or N8 where N is between 0 and F (inclusive). In other words, the last 3 binary digits will always be 0.


Thoughts on how floor drops work (backed up by observation and some testing, but still conjecture)
When you whip on the same frame you fall, the game thinks you are on the ground for that whip. The game realizes that you're in the air though, and decides to make you start falling, and applying gravity until you hit the ground. When you hit the ground, your whip ends and the game decides that since you were whipping on the ground, there is no need to change your y velocity on that frame for some reason; however, since you landed, the game turns off gravity while your y velocity is still max, so you continue to fall through the ground until the game realizes that you're in the air again, when simon's feet are no longer at the top or inside of a square that has a solid block on it. This only works if your whip ends on the same frame that your collision on the block would be detected, which usually depends on what your y sub-pixel is.


There are 3 extra floor drops that we knew about but weren't viable without a setup:

At the beginning of the game, you can walk left, and then do one of 2 things:
1) jump, wait one frame, whip, and when you land you'll be able to do the drop. It's a frame-perfect trick but it's within the first half a second of the start of the game.
2) jump up to the ledge, jump off of it (don't fall) and then jump back up.
Keep in mind, this saves only about 3 seconds which can only be used for farming skeletons at the moment.

After farming 13 heart drops from lizardmen, and climbing the stairs to get the white crystal/holy water, jump any time between the top of the stairs and the ledge that's to the right of the holy water building, then jump up the ledge.
Alternatively, step onto and then off of the stairs that are on the same level as the holy water building, jump up to the ledge, and then jump and hit your head on the ceiling.
This one saves more time than the one above, and is easier, but it still only gives you more farming time.

There's one other floor drop that deranged_squirrel_fighter brought to my attention after killing Camilla and getting another oak stake.
-Fast Setup: Just before the screen transition, step on/off the stairs, jump to the platform that has a skeleton on it, jump over the skeleton (the only time you can whip is juuuuuuust before landing next to the skeleton), and land on the "floor" that leads to the next room, jump up onto the first ledge there, and you can floor drop off the right side of it.
-Easy Setup that will work (I think) 9/16 of the time: just jump one platform higher and jump or fall off (just don't land lower than where you floor drop from)

There's also a crazy set of two floor drops in Nail Mansion, which saves about 1-2 seconds as long as you get it at all
First drop:
-Step onto/off of the stairs right at the end of the set of holy-water-breakable platforms, and jump up to the platform, jump off it to the right to any part you can, jump up to the nearest edge, and drop.
-Throw a knife so that it hits the skeleton on the platform just above where you'll land.
Second drop:
-While the skeleton is stunned, take a few steps left (so you don't get hurt), and jump up to its platform.
-Floor drop before the skeleton hits you (if you're on the verrrry edge of the platform it won't hurt you, or you can kill it but at that point you may be wasting time)

In Nail Mansion, there's one drop you must do in a whip-only run. I'm kinda tired right now so I'm going to assume someone who's doing whip-only already knows where the drop is.
-Take a step on the stairs just before the floor drop, preferably after killing the skeleton on top of them (on the left of it, the ones that you don't usually take, but have to take if you fall down)
-Kill the skeleton on the upper platform, making sure to land before whipping
-Otherwise, normal movement. Note that this floor drop is one of the "inconsistent after you mess up" floor drops (usually if you miss a floor drop by one frame, your y-subpixel will still be A-OK for your next attempt, but not here)



Old floor drops now have setups:

After the skeleton farm: (not sure if this is worth it, as you miss one skeleton and use probably half a second to set up), as you're leaving the farm location, step onto the stairs and then off, jump down to where the skeleton is just before the screen transition and kill him while standing on the ground, or jump over him entirely (if you do this, it's almost definitely not worth it). After you've cleared the skeleton jump one more time on flat ground.

Chain whip room: just don't land on the platform that's just above the one you drop from and you should be OK, this one scrolls the screen in just the right way that it will always (I think) work if you get the right pixel.

Blue Crystal (right after): as long as you approach normally, just jump up the ledge, jump off, and jump back on.

On the way to Heart Mansion: This setup takes about 1.5 extra seconds and requires a jump that might mess up your whole groove. If you mess it up, it's messed up for good.
1: Entering the screen after blue crystal town
---Immediately whip the skeleton, jump up to the platform it's on, walk to the right, and jump to the left from the far right side of the platform.
---Whip as soon after you land as you can be certain that you've landed, in order to kill the skeleton and probably also the spider's web.
2: Middle of the screen
---Jump down the two 1-high blocks, and make sure to land before whipping the skeleton that's there.
---Jump up to the spider, wait for it to get close to the ground, and whip it without jumping.
3: Actual setting up
---You should be OK if you did all that
---If you miss the floor drop (the first time) the recovery differently than a usual floor dorp, since the y-scroll is weird here when you first come from the previous screen.
Note: The y-scroll thing means that this floor drop will work 21 out of 32 times on the first attempt, if you don't get the setup.
IN SUMMARY: Don't whip in the air or get hit, and you *should* be ok.

Heart Mansion, falling down after getting the heart: (let's call the place holding the heart the "pillar" and the two platforms leading up to it the "upper platform" and "lower platform")
After the last set of stairs before getting the heart, don't jump at all, until you have to. When you're about to throw the stake, don't jump to throw it.
-Right side (if you want to buy a stake, I believe): After that, jump down to the location of the floor drop, and do it (if you land on the upper platform and fall down, you can correct the mistake by jumping off the lower platform and jumping back up twice, though I'm not sure that's the fastest way)
-Left side: Instead of not jumping at all before getting to the heart, jump once when you're on the platform you're going to floor drop from, hitting your head on the ceiling.

Someone please tell me if Rib Mansion doesn't go here...
Rib Mansion, dropping around oak stake guy:
-Easy setup (credit to jc583): just climb the stairs nearby
-Other setup: I have to look at this, but I think it's way better to do something different IF you actually get an oak stake (I think it's another screen y position thing where your y subpixel can be more things; some credit will go to jc again because he tried something randomly in a run and it worked, making me think there would be another setup).

Death's Mansion, the drop from the very top of the mansion: The first time around, you generally want a y-subpixel of something like 90 or less (I don't feel it's worth testing). In essence, don't get hit more than once, don't get hit in the air or on the stairs, don't whip jump, and you'll be fine (though I should test this more because it seems like rarely you will get hit in an odd way that sets your y-subpixel to something other than 60 after being hit). If you're sure your y-subpixel is 0 (didn't get hit, and jumped an even number of times [yes, 0 is even]) then the recovery should be to jump up, fall down, jump up, fall down, jump up, and then jump in place. This is kind of slow, so it's probably better to give RNG a shot and whip jump up. Aim for the 4th frame after your jump.
If you get hit once, and miss the floor drop, jump straight up once and you should be fine in many cases.
Note: If you don't think it's worth remembering all this for the recovery, just remember to jump once and try it normally. It shouldn't take that much longer, unless you mess up a bit.

Death's Mansion, the drop that lets you jump into death's room:
NEW:
(this lets you get a 3-frame window for the jump every time rather than a 1-frame window)
(I don't know how to test for sure that this will always get a 3-frame window, let me know if it doesn't work for you)
-climb the stairs *up to the third step at least*
-jump over to the pit (you should be jumping twice to get here, after the stairs)
-fall into the pit
-jump out, onto whichever side
-fall in and jump out again (onto either side, but I only know this works for the right side)
-jump straight up
DEPRECIATED:
-Left side: climb the stairs just to the left of the block, and make the normal 2 jumps over.
-Right side: climb the stairs just to the left of the blocks, and make the normal 3 jumps over, but jump in place one more time at the end.

Death's Mansion, leaving: step onto the stairs just to the left of the step, jump up on the step, jump to hit your head on the ceiling above the step.

I can't think of a good place to put this, because it's no longer in the any% route as far as I know, but...
Morningstar:
Entering:
-Jump up to the morning star room as normal, then jump off, then jump up again. DO NOT JUMP OFF INSIDE THE BUILDING (the y-scroll will screw you up!).
-If you miss this drop, climb the stairs, jump up, jump off, jump up.
Leaving:
-Jump up as normal after the stairs, jump off anywhere and then jump back up.

Camilla's Mansion, drop down to laurels guy:
(I think it's mostly how you normally go through the room, just keep in mind you cannot whip jump)
-On the way to the laurels guy, take a step on the stairs just before the jumping skeleton that you follow into a screen transition.
-Traverse this screen normally (jump up two times, follow the skeleton by jumping down twice and no whipping)
-Jump over the skeleton in the next screen, fall down after it
-Fall down again to the ledge you will drop from
-Fall off the ledge and jump back up
-Do the drop

Dracula's Mansion, drop #1: take a step onto the stairs, jump up to the ledge, jump down, and jump up again. There might be something faster but I can't find it unless you want to do a whip jump (climb stairs, do a jump/wait a frame/whip up to the platform). The first setup may not be worth it.

Dracula's Mansion, drop #2: I'm pretty sure this drop is not worth setting up. It will have a different setup if you get the first floor drop versus take the stairs, and you *have* to jump or fall down as part of it because you fall far onto the platform you want to drop from rather than jumping up to it (screen y position matters for floor drops, if I didn't say that earlier).
The best setup I could find was something like 4 jumps total, which is probably barely faster than walking, and a lot riskier.

Dracula's Mansion, drop #3:
-That the y-scroll for this drop is not ideal.
-Initial setup: Assuming no whip jumps, and that you otherwise get through the section after the second floor drop (which should be skipped, but it doesn't matter), jump up and hit your head on the ceiling just before the drop, where there are 4 blocks of space between the ground and the ceiling.
-Recovery ONLY: If you climb up the stairs all the way from the bottom of the stairs to the top, it will not work. Instead, jump up to the top, and take the smallest amount of time on the stairs you can, or jump off the ledge you drop from (don't just fall, it's hard but you have to hit your head on the ceiling) and jump back up.



Recovery strategies:
General recovery: Anywhere I've looked at but the chain whip floor drop, which is not worth recovering in any way, you can fall down and jump back up 2 times, and you'll have a 28% chance of being set up. If you're really good at getting the frame for the floor drops, don't bother doing this; this attempt at a setup doesn't help if your attempts at floor drops would all be spot on or one frame late.
After blue crystal drop:
-Missing it by 1 frame = get up, jump off, get up, jump off, get up, drop. That's 2 jumps off of the ledge before dropping.
-Missing it by 2 frames = jump up, fall off, jump up, drop.
Heart Mansion Right: If you land on the upper platform and fall down when jumping off the pillar, you can jump off the lower platform and jump back up twice.
Heart Mansion Left: If you make the same mistake as above, don't do the same recovery, instead, just hit your head on the ceiling right before you jump up to where you do the floor drop.
Death's mansion: all of these have setups that are just before the drops, so I don't think recovery strats are worth looking into or even remembering, but if you want to get serious about it, you can look at it in the emulator



To Do list:
Figure out exactly what the y-scrolling thing has to do with y velocity/floor drops
Better Rib Mansion setup if you get the stake, possibly if you don't but it'd save half a second max
Probably look at more recovery strats



Stuff about the y-subpixel:
In this section, I will refer to the y-subpixel as values ranging from 0 to 31 (if you do math and get a value above 31, basically divide by 32 and take the remainder, that's what the value really is).
Most floor drops require your y-subpixel to be 2 or less, but depending on the scrolling position of the screen (on the y axis) you may get a floor drop that has a different maximum; most of the time you jump up to a ledge, and that sets the scrolling position of the screen. I believe that it only matters what the screen is scrolling *to* and not what it's at, but it's hard to tell at the moment. It will require that I (or someone else) look for another value to compare with and research.
Jumping up a ledge that's 2 blocks high will always increase your y-subpixel by 3.
Jumping up 1 block or less will always increase your y-subpixel by 16.
Hitting a ceiling has precedence over the net change in block height, but I believe that it will be a constant amount if you jump up, hit a ceiling x blocks above your starting point, and land y blocks above/below your starting point.
I think that falling 1 block increases your y subpixel by 2, unless it is odd, in which case it increases by 7, but I don't remember for sure whether it was 7, and I'm not sure either number is consistent.
Whipping, throwing a stake, etc. does nothing to your y subpixel.
Getting hit by an enemy while on the ground needs more research, I believe it's consistent though. (at least, it's consistent for each setup, so it's worth testing on floor drops where it's applicable)
Whipping or getting hit while in the air is (usually) inconsistent; it depends on your y velocity when it happens.
Anything I haven't mentioned yet is also inconsistent.

If you want to know what these values are in hexadecimal, 0 is 00, 2 is 08, 3 is 10, etc. up to 31 which is F8.



Finally, for many floor drops as I said before, you can fall down and jump up some number of times and the chance that it will be set up will increase.
If you want to know what chances you have after doing this, look down to the bottom, otherwise I'll paste a separate and relevant table of data below and explain it afterwards:

start	usual	miss by 2
00	0	6	(E8)
08	0	3	(F0)
10	0	3	(F8)
18	13	0	(00)
20	10	0	(08)
28	10	0	(10)
30	7	13	(18)
38	7	10?	(20)
40	4	10?	(28)
48	4	7?	(30)
50	1	7	(38)
58	1	4	(40)
60	1	4	(48)
68	14	1?	(50)
70	11	1?	(58)
78	11	1?	(60)
80	8	14?	(68)
88	8	11?	(70)
90	5	11?	(78)
98	5	8?	(80)
A0	2	8?	(88)
A8	2	5?	(90)
B0	2	5?	(98)
B8	15	2?	(A0)
C0	12	2?	(A8)
C8	12	2?	(B0)
D0	9	15?	(B8)
D8	9	12?	(C0)
E0	6	12?	(C8)
E8	6	9?	(D0)
F0	3	9?	(D8)
F8	3	6?	(E0)

Assume that your y-subpixel is the value under "start". Also assume that the y-scroll is "normal" (what it would be if you jumped up to the ledge, at least in most situations). Then if you fall down the ledge and jump back up N times, where N is the number under "usual", you will be set up to do a floor drop. If instead you try to floor drop, and either get the correct frame or are 1 frame late, the same thing will happen as if you fell off and jumped back up. If instead you try the floor drop and are 2 frames late, you will need to fall off and jump back up M times, where M is the number under "miss by 2" (the value in parentheses is the value that your y subpixel will be if you miss a floor drop by 2 and jump up).
A question mark after a value indicates that I saw the pattern and decided not to test the value and just put it in for the sake of being able to look it up.



The important part is, if you fall off/try a floor drop and get the right pixel/try a floor drop and are one pixel late, then jump back up N times, your chance of being set up after that is as follows:
N	Chance
--------------
0	3/32
1	6/32
2	9/32
3	11/32
4	13/32
5	15/32
6	17/32
7	19/32
8	21/32
9	23/32
10	25/32
11	27/32
12	29/32
13	30/32
14	31/32
15	32/32