Glitchy Ledge Grab: Difference between revisions

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[[File:GLG.gif|thumb|GLG at [[The Secret Aquarium|SA]] Entrance]]
[[File:GLG.gif|thumb|GLG at [[The Secret Aquarium|SA]] Entrance]]
A '''glitchy ledge grab''' or '''GLG''' is a kind of [[Ledge Grab|ledge grab]] that goes higher than a normal ledge grab.
A '''glitchy ledge grab''' or '''GLG''' is a kind of [[Ledge Grab|ledge grab]] that goes higher than a normal ledge grab. While a regular ledge grab can only allow Mario to ascend up to 150 units, a glitchy ledge grab allows Mario to ascend up to 238 units. This can allow Mario to reach areas he could not normally, particularly in the context of challenges such as the [[A Button Challenge]].
==Details==
==Details==
A GLG can ascend slightly more than 238 [[unit]]s up, compared to only 150 units from a regular ledge grab. The game does two ledge grab checks, one at Mario's lower body and one at his upper body<ref>https://discordapp.com/channels/267091686423789568/309838966125756416/495070903177314305</ref>. When Mario's lower body touches a [[wall]] and not his upper body, the game looks for a floor to grab onto. This happens when it is within 50 units from his feet, but more than 50 units from his head. Alternatively, 30 units up there is a wall but 150 units up there is not one, this time measuring from Mario's feet. A glitchy ledge grab is when those two things don't line up quite right, so Mario is able to grab a ledge he normally wouldn't be able to. A GLG can be triggered because:
If Mario is moving in the air with non-positive vertical speed, the game checks whether Mario can grab a ledge with two conditions. First, the game checks a 50 unit radius around Mario's position to see if there is a wall 30 units above Mario's position and no wall 150 units above Mario's position. Then, the game checks if there is a ledge Mario can grab on by looking at his x and z coordinates before being displaced by the wall and his y coordinate plus 160 units, looking for the highest floor below those coordinates, and checking whether that floor is at least 100 units above Mario. <ref>https://github.com/n64decomp/sm64/blob/master/src/game/mario_step.c</ref>. Additionally, when the game looks for a floor, it includes a 78 unit buffer giving the floor search an effective height of 238 units. A glitchy ledge grab occurs when those two conditions are satisfied in unusual ways, so Mario is able to grab a ledge he normally wouldn't be able to. A GLG can be triggered in a few ways:
* The wall is slightly tilted, so Mario's lower body touches it but not his upper body, which triggers a ledge grab check when there isn't supposed to be one (used in the [[A Button Challenge]] to enter [[The Secret Aquarium]] 0xA)
* The wall is slightly tilted, so Mario's lower point is within range of it but not his upper point, which triggers a ledge grab check when there is not supposed to be one (used in the [[A Button Challenge]] to enter [[The Secret Aquarium]] 0xA) <ref>https://www.youtube.com/watch?v=7YhJcF9v7QQ</ref>
* Mario's lower body touches a wall, but it detects the wrong floor because of the direction it searches in (used in the [[A Button Challenge]] to go to [[Bowser in the Sky]] 0xA)
* Mario's lower point is near a wall, but it detects the wrong floor because of a difference in the orientation of the wall hitbox and the direction the game uses to find the x,z position the floor is searched in (used in the [[A Button Challenge]] to go to [[Bowser in the Sky]] 0xA) <ref>https://www.youtube.com/watch?v=Ii2rvLDd09I&t=1069s</ref>
* Mario's lower body touches a wall, but it detects the wrong floor because the floor search starts 238 units above Mario, which is too high
* Mario's lower point touches a wall that ends as intended, but it detects the wrong floor because the floor search starts 238 units above Mario, which is high enough to find an unintended floor.
* Mario's lower point is near a wall, and his upper point is aligned exactly with a gap in the wall due to float imprecision. <ref>https://www.youtube.com/watch?v=j5VSzpl-Xdg</ref>
 
==References==
==References==
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Latest revision as of 20:53, 4 December 2022

A glitchy ledge grab or GLG is a kind of ledge grab that goes higher than a normal ledge grab. While a regular ledge grab can only allow Mario to ascend up to 150 units, a glitchy ledge grab allows Mario to ascend up to 238 units. This can allow Mario to reach areas he could not normally, particularly in the context of challenges such as the A Button Challenge.

GLG at SA Entrance

Details

If Mario is moving in the air with non-positive vertical speed, the game checks whether Mario can grab a ledge with two conditions. First, the game checks a 50 unit radius around Mario's position to see if there is a wall 30 units above Mario's position and no wall 150 units above Mario's position. Then, the game checks if there is a ledge Mario can grab on by looking at his x and z coordinates before being displaced by the wall and his y coordinate plus 160 units, looking for the highest floor below those coordinates, and checking whether that floor is at least 100 units above Mario. [1]. Additionally, when the game looks for a floor, it includes a 78 unit buffer giving the floor search an effective height of 238 units. A glitchy ledge grab occurs when those two conditions are satisfied in unusual ways, so Mario is able to grab a ledge he normally wouldn't be able to. A GLG can be triggered in a few ways:

  • The wall is slightly tilted, so Mario's lower point is within range of it but not his upper point, which triggers a ledge grab check when there is not supposed to be one (used in the A Button Challenge to enter The Secret Aquarium 0xA) [2]
  • Mario's lower point is near a wall, but it detects the wrong floor because of a difference in the orientation of the wall hitbox and the direction the game uses to find the x,z position the floor is searched in (used in the A Button Challenge to go to Bowser in the Sky 0xA) [3]
  • Mario's lower point touches a wall that ends as intended, but it detects the wrong floor because the floor search starts 238 units above Mario, which is high enough to find an unintended floor.
  • Mario's lower point is near a wall, and his upper point is aligned exactly with a gap in the wall due to float imprecision. [4]

References