speedrun thread

King of Posters
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SUB 50!!! WOOOOOOOOOOOOOOOOOOO

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Wallboosting is a technique I discovered in King’s Field 3 (it appears to also work in KF2). There are two basic forms:

1. Straightboosting - When you align yourself very close to perfectly parallel to a straight wall while touching it, you will sometimes receive a speed boost that lasts as long as you are touching the wall while running beside it. It is believed that the amount of the boost varies based on how closely aligned you are to the angle of the wall. Excellent straightboosts appear to boost movement speed by as much as 2x over normal, possibly more. Changes in elevation will sometimes cause boosts to stop working, e.g. while on staircases or slopes.

Examples:
https://clips.twitch.tv/LongFrozenTomatoPeteZaroll
https://clips.twitch.tv/EvilGenerousTardigradeBrokeBack

2. Strafeboosting - While strafing and running forward simultaneously (bi-coording) does not seem to be faster than just running or strafing alone in any KF games (as opposed to games like Doom and Goldeneye 007, where it is always faster to be strafing+running in concert), there is a separate form of wallboosting which requires using this technique while aligning yourself with a wall. When you are bi-coording perpendicular to a straight wall, your speed will increase somewhat at the time you make contact with it. Generally, this type of boosting is not as fast as a tightly-aligned straightboost. However, it appears that aligning your movement to the wall as closely as possible (as in straightboosting, but angled in this case as you are bi-coording) allows for an even greater speed boost than strafeboosting alone. The boosts do not seem to be additive; straightboosting speed simply overrides strafeboosting when at the correct angle. In KF2, where the framerate is much more volatile, strafeboosting is also effective in reducing lag significantly in many areas due to allowing fewer objects to be rendered while the player is staring at the wall.

Example:
https://youtu.be/pgRWz3293os?t=1427 (timestamped to 23:47)

Note: This guide refers to the games by their Japanese numbering:
King’s Field (JP)
King’s Field II (JP) - King’s Field (US)
King’s Field III (JP) - King’s Field II (US)
King’s Field IV (JP) - King’s Field: The Ancient City (US)

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i really want to know if any of this makes sense to any of the developers in this forum. i’m still iffy about if strafeboosting actually works the way i think it does because it’s a lot more subtle than the really obvious straightboosts i linked above. it’s complicated by the fact that it sometimes reduces lag, which, in KF2 at least, seems to speed you up in a similar manner, even accounting for the higher framerate under lower lag conditions.

i’m pretty sure strafeboosting is a thing, don’t get me wrong. i just want more understanding of the innards

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It sounds to me like you’re exploiting collision resolution; is pushing against walls a fairly common speedrunning technique?

Basically, game physics looks at where objects have moved since the past check and looks for objects penetrating solid surfaces.

Game objects record their position but don’t have an understanding of what that means; it’s just a position until you do the math of checking whether shapes intersect each other. So ‘movement’ is just updating the numbers recording position and then drawing them properly in the new spot and checking if that means it’s touching other things, and whether that triggers things, and so on.

If an object is detected penetrating a solid surface, like a wall, the game applies force to push them out (before it’s rendered) (this is called collision restitution). If the game does not a) clamp character max speed appropriately, nor b) applies friction for a player sliding against a wall, you can easily end up with the collision resolution movement adding to the normal player movement, resulting in a speed increase.

Now, collision restitution is usually done with limited information about how far to push. If the system pushes too far or too little, and an object is pushed into another object, physics will perform more restitution. If it keeps pushing but that pushing isn’t getting the object out of penetration, these forces can stack over many iterations and lead to wild physics explosions (many iterations at 30 frames per second can cause this in a fraction of a second). When you’re talking about something like a bipedal ragdoll, it’s a hard problem because you’re trying to push each bone out of penetration but that might be causing other bones to penetrate, and if you combine that with restrictions on how far certain joints can move, which itself gets resolved in another sweep, you can see how these more sophisticated physics shapes can get themselves stuck.

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Yes, it’s in Doom speedruns. Wallrunning | Doom Wiki | Fandom

Here’s an explanation that seems mostly consistent with your evidence. First, assume the underlying reason why wallrunning works is the same in KF2 as it was in Doom (“When a player encounters an obstacle, the game will attempt to “slide” the player alongside the obstacle.”). Separately, the strafe and forward movement are not summed independent vectors as in Doom but rather a diagonal vector of a radius of a circle (so conventional straferunning doesn’t work in KF2). However! The wall-sliding logic is not rotating this diagonal vector, but rather is summing two additional vectors to it based on both the original strafe and forward movement inputs.

In practice, it might be more complicated than this. Pre-middleware games accumulated a lot of arbitrary hacks so they can be difficult to reason about.

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A developer reacting to an explanation of a trick in their own game:

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Goodness that’s a heavy time save.

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you’re showing up in my yourtub recommendations now
do you have the world record in every kings field in every category??

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Meauxdal truly is the Royal Groundskeeper (and I mean that in the best way)

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sub-46!
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when the kings field world record progression video by summoning salt

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so close
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DONE

oh btw i was on mushrooms when i did this run lol

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the most advanced speed tech

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Finally broke sub-35 RONIN today but that was with a major hiccup that lost me over a minute. So I guess I’m pursuing sub-34 now, possibly aiming to eclipse my other categories that hang in sub-33 land. The work is never over! :I

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