Ice Floor Clips: Difference between revisions

From Zero Mission Speedrunning Wiki
Jump to navigation Jump to search
No edit summary
(Completely rewrote the description of why the glitch occurs)
 
Line 1: Line 1:
There are a couple rooms where it is possible to clip into the floor using the ice beam on respawning enemies, and one room in particular where this clip saves a significant amount of time in the 100% run. In order to make the ice clip possible, the following conditions must be met:
Ice Clipping involves using a glitch with frozen enemies that cause you to instantly get moved to their spawn location. In order to trigger it the following criteria need to be met:


* The respawning enemies must be rising vertically out of the ground
* Two enemies need to be frozen close enough together that it is possible to stand on both of them at the same time.
* At least one non-respawning enemy in the room must be killed, and its drop is either collected or wait long enough for its drop to disappear
* At least one of these needs to be an enemy that respawns
* The enemy whose spawn point you wish to warp to must be in a "later" enemy slot than the other enemy (will go into more detail below)
* Both enemies need to die on the same frame, easiest to do using a bomb


If you do not kill a non-respawning enemy then the overlapping freezing effect will not work. Luckily for the 100% run there is an enemy that is literally in your way so this is not a problem unless you go out of your way to let that enemy live.
If you set this up correctly then when the enemies die, Samus's Y position will be hard set to the Y position of the enemy's spawn point. We believe this works because the game will actually pre-load enemies into memory even if they will only spawn later, and will instantly be moved back there upon death, ready for Samus to walk close enough to trigger them again. By killing two of them on the same frame, a sort of edge case is hit where the enemy's death trigger will "put" Samus on top of the ''other'' enemy rather than just let the physics engine handle it. Depending on the order that these death triggers happen, this "other enemy" could already have had its position moved back to its spawn point, sort of dragging Samus with it. Though this is mostly speculation.
 
While this is technically possible on any respawning enemy, it is only really useful in one spot of the 100% run.
Curiously, that particular spot triggers the glitch on a set of pipe bugs that spawn 3 at a time, which would usually make the third criteria somewhat tricky to set up. Because even though all three pipe bugs will eventually respawn, only the first one is actually pre-loaded and moved back to spawn instantly upon death, and the others spawn in on demand. If you just trigger the pipe normally, the bugs will naturally line up in memory in such a way that the glitch doesn't work. The solution to this is to free up a slot in memory by killing some other enemy that is loaded before the original pipe bug, so that when the second bug spawns it will take up THAT slot instead of taking a later one. Thankfully, one such enemy is actually in our way anyway when going through the room the way you would during a run, you just need to make sure it is killed.


The steps to perform the clip are:
The steps to perform the clip are:


* Line yourself up so that 2 of the enemies come after you at the same height and overlap each other
* Line yourself up so that 2 of the enemies come after you at the same height and overlap each other
* Fire two shots to freeze them so that they are overlapping each other while frozen
* Fire two shots to freeze them so that they are overlapping each other while frozen. Very conveniently, because of our earlier enemy slot manipulation, the second bug is also prioritized for projectile collisions, meaning that when you shoot at both bugs when they're overlapping (because you already froze the first one so it stopped moving) the second bug is always the one that gets hit.
* Get on top of them so that you're on both enemies at the same time, and kill them with either a bomb or screw attack.
* Get on top of them so that you're on both enemies at the same time, and kill them with either a bomb or screw attack.



Latest revision as of 13:21, 21 October 2020

Ice Clipping involves using a glitch with frozen enemies that cause you to instantly get moved to their spawn location. In order to trigger it the following criteria need to be met:

  • Two enemies need to be frozen close enough together that it is possible to stand on both of them at the same time.
  • At least one of these needs to be an enemy that respawns
  • The enemy whose spawn point you wish to warp to must be in a "later" enemy slot than the other enemy (will go into more detail below)
  • Both enemies need to die on the same frame, easiest to do using a bomb

If you set this up correctly then when the enemies die, Samus's Y position will be hard set to the Y position of the enemy's spawn point. We believe this works because the game will actually pre-load enemies into memory even if they will only spawn later, and will instantly be moved back there upon death, ready for Samus to walk close enough to trigger them again. By killing two of them on the same frame, a sort of edge case is hit where the enemy's death trigger will "put" Samus on top of the other enemy rather than just let the physics engine handle it. Depending on the order that these death triggers happen, this "other enemy" could already have had its position moved back to its spawn point, sort of dragging Samus with it. Though this is mostly speculation.

While this is technically possible on any respawning enemy, it is only really useful in one spot of the 100% run. Curiously, that particular spot triggers the glitch on a set of pipe bugs that spawn 3 at a time, which would usually make the third criteria somewhat tricky to set up. Because even though all three pipe bugs will eventually respawn, only the first one is actually pre-loaded and moved back to spawn instantly upon death, and the others spawn in on demand. If you just trigger the pipe normally, the bugs will naturally line up in memory in such a way that the glitch doesn't work. The solution to this is to free up a slot in memory by killing some other enemy that is loaded before the original pipe bug, so that when the second bug spawns it will take up THAT slot instead of taking a later one. Thankfully, one such enemy is actually in our way anyway when going through the room the way you would during a run, you just need to make sure it is killed.

The steps to perform the clip are:

  • Line yourself up so that 2 of the enemies come after you at the same height and overlap each other
  • Fire two shots to freeze them so that they are overlapping each other while frozen. Very conveniently, because of our earlier enemy slot manipulation, the second bug is also prioritized for projectile collisions, meaning that when you shoot at both bugs when they're overlapping (because you already froze the first one so it stopped moving) the second bug is always the one that gets hit.
  • Get on top of them so that you're on both enemies at the same time, and kill them with either a bomb or screw attack.

If done correctly, Samus will teleport under the floor as they're killed. The bomb method is easier because you have a lot of time to morph, lay the bomb, and then unmorph so the bomb doesn't propel you upwards when it explodes. The screw attack method requires jumping high enough that Samus will bounce when landing, and you need to unmorph on the frame you would have bounced in order to put Samus into a hover state. This allows you to spin and activate the screw attack while also being stuck on their hit boxes.

Easy Method

The easy method involves hugging the left wall as your falling. This sets up the 3 enemies so the first can easily be frozen and kept out of the way, while the other two will rise above samus and give you extra time to time your shots to overlap them. This method is slower because of the extra time waiting for the enemies to rise, and having to jump on top of them after freezing them.

Faster Method

The faster method involves swinging out to the right as you're falling, and then moving left to activate the enemies at a position where they won't rise as high and they'll come after you faster. This also has the benefit of being able to land on the enemies immediately after you freeze them.

Swag Method

The screw attack method is known as the swag method because the frame perfect unmorph adds an unnecessary level of difficulty to an otherwise simple trick.