Difference between revisions of "Hookpush"

Revision as of 03:40, 29 May 2021

Hookpush is a Major Glitch that uses Misslotting to alter the values the Hookshot uses to determine how far and in what direction to pull Link when the hook latches onto something. Because the game mostly ignores collision while Link is being dragged by the Hookshot, this can be a very powerful glitch for bypassing walls and other obstacles.

Loose Explanation

Normally, when Link uses the Hookshot, a Hookshot ancilla is loaded into Slot 4 and a counter in that slot will immediately be set to 0 and then increment every frame the Hookshot is extending. When the Hookshot connects with an object to pull Link to, the counter will decrement every frame as Link is pulled to the object, with Link stopping when the counter gets back to 0. But what if we can get the Hookshot to look at different counters outside of its current ancilla slot? That's how this glitch is gonna work.

$039D is a memory address where the Hookshot's current slot value is stored when we use the Hookshot, and it is referenced when the game starts pulling Link to determine which slot's counters the game should use. A Somaria block placed in Slot 9 will decrement the value at this address every frame. This means that if we have a Somaria block in Slot 9, and we use the Hookshot with no other ancilla loaded, the Hookshot will spawn in Slot 4 and the counter for Slot 4 will increment until the Hook connects with an object. For the first frame of pulling, the Slot 4 counter will be used, but then, because of the Slot 9 block decrementing the value at $039D, the next frame of pulling will read data from Slot 3, the third frame of pulling from Slot 2, then Slot 1, and then finally Slot 0, where it will continually use this counter until it reaches 0.

Through using other ancillae in specific ways, we can manipulate the counters in other slots to get the Hookshot to pull us for extended durations and/or in the incorrect directions. Or even have it pull us to EG.

General Technique

Labeled Ancillae Super Watch

In order to Hookpush, we want to do a few different things:

1. Misslot a Somaria Block into Slot 9. This requires a couple of steps:
   1. Get the Search Index higher than 09. There are multiple ways to manipulate the Search Index, and the best way may depend on the specific Hookpush you're doing. However, the most common way to get a value higher than 09 is to quickly use the Lamp 3 times while Link is facing any direction except right. Not many things that crop up in normal gameplay write to this address, and only hard resets will put it back to 0. So you can often set this value way ahead of the exact room/moment where you want to do a Hookpush.
   2. Fill the Front Slots (slots 0-4) with ancillae. This is necessary because Somaria blocks will occupy a Front Slot by default, but we want it to load into Slot 9.
   3. Have an ancilla in Slot 9. When we go to use the Cane of Somaria with the Front Slots filled, the game will take the value of the Search Index and look from that value down until it finds an ancilla to replace. If we have an ancilla in slot 9, the block will load there, which is exactly what we want. Usually, we'll hold a sword charge to do this, since the sparkles that appear on the sword use Slots 7-9 by default.
   4. With the Search Index set above 09, all of the Front Slots occupied, and an object loaded in Slot 9, we can use the Cane of Somaria and a block will be loaded into Slot 9. This will appear on the HUD as 2C in Slot 9.
2. With a block in Slot 9, when we use the Hookshot, the game will look at the counter for the Hookshot's slot for the first frame of the Hookpush and then for each subsequent frame it will use the counter for the next slot down until it reaches Slot 0, where it will stay until the counter at Slot 0 had decremented down to 00. How we choose these counters for the results that we want depends heavily on the context, and if you're looking to learn a specific Hookpush, you can go read the Applications section for info specific to what you're learning. But here are some general notes that can help you understand the manipulations being done:
   1. We'll generally want the counters in the slots between the Hookshot's slot and Slot 0 to be a value other than 00 or FF. If any of these values are 00 or FF, then the Hookpush will end on the frame the game is using that counter. By default the Hookshot will spawn in Slot 4, and if that's what the setup calls for, then you'll want the counters for Slots 1-3 to be any value other than 00/FF. You can also force the Hookshot to load into different slots. If I place a normal Somaria block (defaults to Slot 4) and then Dash Dust (will load in Slot 3), then my Hookshot will spawn in Slot 2. Now the Hookpush will ignore data in Slots 3 and 4, and the Hookshot itself will set a good counter at Slot 2, meaning the player only needs to manipulate the counters at Slots 1 and 0. This can be very useful in some contexts.
   2. Generally we'll want the counter at Slot 0 to be a high value. This is because when the Hookpush gets to the counter in Slot 0, it will use only this counter until it decrements to 00, when the Hookpush will end. Because Sword Beams write 4C to their slot's counter, a Slot 0 Sword Beam is often used for this. 4C in decimal is 76, meaning we get a whopping 76 frames of Hookpushing with that value.
   3. Somaria blocks run their code even when the game is paused to the item or S&Q menus. This includes Slot 9 Blocks and how they decrement the value stored at $039D every frame. The Hookshot does not function while the game is paused though, and this quirk allows for more setups. You can, for example, have a counter set to 00 in Slot 1, which would ordinarily mean the Hookpush will terminate there before it can execute the data stored in Slot 0 (generally a very high counter). BUT if you use the Hookshot and pause the game just after it latches onto something, the Slot 9 Somaria block will be decrementing $039D every frame, meaning when you unpause, the Hookpush will be reading Slot 0. This is a useful way to bypass slots that have data you don't want to use.
   4. Directions aren't displayed on the Ancilla HUD, but these are also very important for Hookpushing. Just like the Hookpush is using the counters set by other ancillae, it will also use the direction of other ancillae. If I do a Slot 0 Sword Beam to the south, the Hookpush will use that direction while using Slot 0's counter, regardless of which direction I'm actually using the Hookshot in. The direction of Slot 0's ancilla in the setup is especially important, as this is what most of your Hookpush frames will be using. Some setups are positionally sensitive enough that the directions set in other Slots are significant as well.
   5. If you don't want to enter EG, you'll want your EG Check value to be 00 or you'll want to have Weak EG set. It's important to note that this watch is viewing the EG Check at Slot 0. This is very relevant for avoiding unintentional EG since you'll typically be using Slot 0 to do the Hookpush, but if you want to enter EG, you can end the push early and use a different slot's EG Check value, which won't be displayed on the HUD. Currently most setups used to Hookpush to EG do use a higher slot with that slot's counter at 00 or FF (so the Hookpush stops at that slot) but the EG Check for that slot is set above 00.

Applications

Chicken House to Witch Hut

Fish Room Hookpush

Hammerbridge Hookpush

Ice Fairy Room Hookpush

Ice Entrance EG

Kakariko Shop to Ice Cave

This Hookpush is currently used in the All Dungeons MG Speedrun as a way to collect Ice Rod quickly. It also has a useful side effect of easily getting 10 Bombs.

Technique

• First make sure your Search Index is set high. This can be done well before coming here, and in the videos, it's already set to a good value.
• Place a Cane Block in the room. It's good to make sure that when you pop the block all four beams have plenty of room to travel before hitting a wall and despawning. You should now have object 2C in Slot 4.
• Hold sword and then quickly pop the block, dash dust, and place another block. The beams from the Somaria block (objects 01) will occupy Slots 1-4, your dash dust (object 1E) will occupy Slot 0, and the second block you place (object 2C) will be placed in Slot 9.
• In the current speedrun where this Hookpush is used, bombs are bought here. Although the "item get" is an ancilla, it doesn't actually factor into this setup.
• Dash dust and place a regular block. This will put 1E in Slot 4 and then another block (2C) in Slot 3. This is important because we want another block, but if we just place one, it will be put in Slot 4. Slot 4 blocks will delete blocks in Slot 9 (very bad).
• Pop the block and quickly slash right twice. Somaria beams (01) will occupy Slots 1-4. Your first slash will have a Sword Beam (0C or 04, the ancilla will have a different ID if it hits a wall, but lucky for us, either one sets a good counter value) in Slot 0. This should also mean that the counter for Slot 0 is now 4C. It's essential this 1st slash is done before any of the Somaria beams despawn. We want our 2nd slash to come after two of the beams have despawned (the top and right ones). The bottom and left ones should still be there in Slots 2 and 3. A new sword beam will spawn in Slot 4, and a slash sparkle ancilla (26) will spawn in Slot 1, which will set the counter there to 04.
• Now just dash dust and slash while walking south to the bottom right corner of the room. This will put dash dust (1E) in Slot 4, a Sword Beam (0C) in Slot 3, and a Slash Sparkle (26) in Slot 2. This should set the counter in Slot 3 to 4C and the counter in Slot 2 to 04.
• All of our values should be set now. Check that the counters in Slots 1-3 are non-zero and that the counter in Slot 0 is 4C. If so, you were successful and you just need to Hookshot the torch from the bottom right corner of the room.

Mire Entrance EG

Skull Big Chest EG

Swamp Entrance to Mothula Crystal

TR Entrance EG