Could the problem be that the stairs are also not made with the speed your character has to move in mind? I think that the only way we will get natural stair movement is when we lock characters to the stairs and use an IK and root motion setup that calculates where you can put your feet. Maybe faster characters could go up 2 or 3 steps at once.

Stairs used to be this thing I would not notice in games until GTA IV. I still remember when I first played and Niko started stepping on each step and jumping some if running, it was insane.

When I was a kid, I would be really impressed or fascinated with how in the original Wind Waker on gamecube, Link's feet would stand on and set up each stair individually. You could stand on the stairs and one foot will be on the next step and one on the lower step. It always looked so smooth.

Harry Potter and the Order of the Phoenix was a videogame that dealt very well with stairs, whenever you were going up or down stair the character moved at a compatible pace, and physically actually stepped on each step like a person would in real life. Actually pretty advanced for a PS2 game, all things considered.

Breath of the Wild also has some good examples of making step-ups feel even more natural. On really REALLY short steps it's just the typical smooth looking motion. But as the steps get higher Link begins to do an actual "stepping up" or "clambering" style animation, which influences his movement without interrupting the player's agency, and makes a high step-up look seamless

Something that's always weird to me is that stairs usually look proportional when you're playing, but your character always runs up them like 7-10 steps at a time. In real life, if you're running up stairs full speed you can get 3 at a time, maybe 4 if your legs are long. But VG characters just fly up a whole flight in 2 strides.

For years all I've ever wanted was to have my player model in any game actually have their feet match on each step as they go up the stairs, rather than stand on one and slide up a few. A few games have done it but its made the stairs feel more likie a cutscene than being actually fluid with character movement, and I've always wondered that surely it wouldn't be that hard to do. After seeing how much work actually just goes into regular ol stairs I finally understand why it must be so hard for that kind of coding jesus. Thanks for making this vid, it was super informative I greatly appreciate you putting in the time to make it

I've made a fair amount of character controllers in my spare time and the floating character method is definitely my favorite solution. It's simple, reliable, and feels very smooth. I would highly recommend it to anybody making an indie game. The very very valet video he references at 3:38 is actually a full tutorial the devs of that game made and it's very helpful, I'd recommend anybody who wants to make a floating character take a look at it.

Snapping has a really bad problem that you seemed to ignore in this video. When you use the snapping method, many games don't include a decent enough compensation for the camera snapping in turn. This can cause motion sickness in some players, especially if the title is a first person game. This is why most first person games use clip brushes to handle stairs rather than snapping, especially highly competitive games such as counter strike or overwatch. Thus, as with most game design decisions, the correct answer rarely is one size fit all, but highly a "it depends". Also note that these aren't the only two options, another example are games such as the Yakuza titles that choose to (atleast most of the time) force you to walk up/down stairs normally, with pre-determined animations for each step. These fit better than either of the two previous solutions for games that are trying to stay more grounded in reality, and there are more options out there too.

A fun example of a game with no minimum step depth is Minecraft. You can stack up a bunch of random blocks to make very steep staircases

AAA dev here. To get the best of both worlds between the consistency of step snapping versus the smoothness of ramps, you can use the snapping, but afterwards apply a dampened spring offset to the character model relative to the capsule. With the spring tuned properly, this makes it so you can author the stairs as normal, get the good behavior of the step snapping, but you don't have the visuals of popping up and down the steps. Paired with some good IK, this is pretty much the de-facto modern stair solution. The spring also helps if you have a very rough terrain.

Have you seen the escalators in Lost Judgement? I was blown away when i saw the protagonist walking up and down FULLY FUNCTIONAL ESCALATORS, with each foot connecting perfectly with each step, adapting to the speed. Literally the best stairs I've ever seen in a game, and they move! Not sure of its something you have time for, but if you're ever able to figure out how they worked that magic, I'd love to hear about it. Your way of explaining things is great.

one problem i always found with stairs is that they never lead up to anywhere good

On snaps: They can be EXTREMELY disorienting for VR. The sudden up and downs on climbing steps can feel horrible, even for somewhat experienced VR users. The "ramp" approach feels better in taht case. :P

0:04 I know a guy on the west end for that

I do not feel high enough, but I don't think my solution is climbing or stairs 0:10

TF2 maps mostly cover stairs with ramps, but there’s a few maps (or a few sets of stairs) that don’t do this and instead you snap to each step. It’s noticeable when this happens. Your view snaps to each step with you and it can be jarring. The ramps are a good workable solution. I guess, the best stair solutions depend on the type of game. For FPS games, you probably just want a ramp to make it simple.

The absolute best solution for this problem for me was shortening the capsule collider up to the knees and adding a downward-facing raycast that checks how far the ground is. It then lerps you to the raycast position every frame. So far it hasn't failed me and I'd assume it costs less than checking contacts

I love the way the characters go up and down stairs on Resident Evil 1 Remake. You should check it out! It feels really good and it doesn't have that awfull thing where a character seems to ignore the stairs' geometry completely

I'm not an animator, or game dev, but stairs in games always mattered to me. The ones that bother me are ramps with stair textures. I would rather they used ladders if they wouldn't want to animate stairs properly, especially in games that are aiming for immersion.

Using snap up/down code is all fine and well, but people don't rigidly move over obstacles as we naturally keep our heads at a steady height. To accurately move characters over small obstacles and up/down stairs in a realistic manner you'd have to predict that your character is about to go up/down and make the IK legs anticipate changes in elevation, followed by smoothly interpolating between the heights. There's research papers on this (Phase-Functioned Neural Networks for Character Control, Daniel Holden et. al, 2017), but that's really getting into the weeds of things. Ultimately anything less than neural networks and predictive movement is a compromise, but games are made on compromises for reasons ranging from performance to game feel, and more. I mean, competitive shooter games might even opt for ramps only so that player heads (the main way to define skill by clicking on them) aren't jerkily moving up and down that would otherwise disrupt player aim and cause missed shots. Personally I still prefer the invisible-ramp-inside-fake-staircase method for its consistency and smoothness despite the additional work for non-stair steps (and even that might be easy to solve by "baking" a level's steppable areas like you would bake a lightmap - and for procedural levels it wouldn't be too difficult to add additional checks as to where invisible ramps should go in the level generator code).

I am a gamedev myself and I think it's a very interesting and well made video and 3d visual animations are very helpful!

Back in my early days of programming I solved the "stair problem" on my kinematic controller with an absolutely overdesigned solution involving a whole bunch of casted sloped colliders and edge case handling. The colliders would cast forward at the character's feet and essentially act like there was a ramp there for them to walk up. It was fairly rigorous but it was absolutely unmaintainable and not performant and was not entirely free of weird edge cases. This was before I had learned that simple is usually better.

Before stair motion can even be fully considered i feel that matching the characters moving speed and animations is really important, if it looks like your feet are sliding under you even on solid ground because the speeds don't match, stairs will never look natural even with a perfect all encompassing stair solution

4:24 Valve has been trying to figure the whole curved staircase thing out for the past two decades... they know how painful it is.

I saw a video about wheels and terrain, and formulas to calculate how any shape can be a wheel with a specific terrain. The most common one is a square wheel, which it's terrain is just bumps that look like half circles in 2d or half cylinders in 3D. Smoothness was defined by having a point inside the shape that remained linear in motion taking into account the wheel and the terrain. Maybe something like that could be done to solve the stair problem. Define a point that you want to maintain linear motion, like the player torso, and then make the bottom half of the player adjust to the heigh difference between the step you're on and the next one and rest the difference to the upper half so it maintains the same height no matter what the bottom half bumps into. Somewhat like wheel suspensions.

I think this is a great video! With procedural animations, stairs are pretty simple to create, you won't need to have in mind the player speed either because the dot that follows each set of stairs is relative to the position of the players legs :)

The trick of having Tha character just "float" above the ground sounds very nice, the hidden with their feet and stuff, might actually work well, I want to try that. Very nice video!

Why not have the player collider use the ramp, and have the IK use the stairs? You could also sorta "flatten" the ends of the stairs so that going up the stairs isn't a constant motion. The ramp at the edges, combined with the IK snapping to the flat stairs, visually simulating the effect of the character's legs pulling the rest of the body upwards.

OK before the final solution comes up for me, here's what I think: Use a ramp collider on all steps, and give your player two types of colliders. A rectangular or triangular one for each foot that collides with the visible step using IK animation, and a capsule one for the root of the player model, that collides with the ramp. Depress the ramp collider into the stairs *just* enough for the feet to be able to travel down to the step without stretching the model. The player should slide smoothly up and down the steps, (which would have to have their angle defined by the level designers) and the feet should reach down to meet the actual step at the same time. Essentially: "Don't do that. Just make it *look* like you're doing that!" You're moving up and down a ramp that *looks* like stairs.

as someone who isn't any sort of game developer, i find that i don't think about stairs in any sort of way but this video has shown me just how complex all these stairs i have ascended and descended in games, and you looked at the third person pov, first person i would imagine would be more complex as having all those bumps up the stairs might be a motion sickness issue with all the jittering happening. that aside very informative video now whenever i ascend and descend stairs in a game i will know just how complex they really are.

The first retro game that comes to mind when it comes to high-effort player character animation for me is Jak and Daxter, so this video made me try to remember how stairs are handled there. I then realized that everything that could be considered stairs are exaggeratedly large, adjusting with how far into the game you are. (The steps to the final boss each being twice Jak's height.) The idea that they did that partially to avoid stair-step animations is really funny to me.

fun fact. Source engine uses the same snap up and down idea you are using. but they set the minimum snap depth really small. so you can literally climb up a near 90 degree wall as long as there are tiny 1/16th in ledges every foot up.

In my experience (and I have written sphere sweeping) your capsule will go over low steps and rough terrain just fine. Getting the animation to look realistic is a different story. Also an overhang will make no difference if it's low enough. It has to be under half your bottom sphere but maybe a 3rd is better. But it reacts the exact same as a regular step.

Really makes you appreciate the finer details of game development, and especially the fine touches like Link looking down when he goes down steps or up as he approaches a wall in tears of the kingdom

I really appreciate this kind of content, I started making games when I was becoming a teenager (I'm not sure what is the correct term in english). But only recently, I started to realize that games aren't made with special assets, systems and engine features taught by famous tutorials that solves your problems magically, instead it's a endless problem solving process, and with problems that you never really thought existed until you start making games, like stairs. Really nice content! Videos like these desmitifies game development!

Good ideas here! I'd like to see you address two other common issues: 1. Ramps and Gravity - does the player have gravity on flat land, or only step slopes + the air? 2. World Floating Point Precision - does the player move around the world or the world around them? Also, my take on the stairs problem is to treat them like ramps from edge to edge when going fast (making a big ramp) or small, step ramps from edge to an inch below when going slow.

It's generally still better for a level designer to add a ramp their stairs even if the snap stair movement method is used as it makes stairs look much smoother.

You mentioned the floating method. When I was trying to solve this without looking at tutorials cause I'm stubborn and wanted to solve it myself, it felt so good when I finally figured out that I can just make the collision float and maintain a minimum distance to the ground. It's so incredibly easy compared to all other methods. I don't get why you didn't talk more about that one. Of course just making the collision float is just part of the solution: I also made the character move along the normal of the surface instead of directly where the input says, changed the speed depending on the angle, etc.

Another graceful solution to consider has to do with physics masks. Since the movement of the player you're attempting to achieve is that of a ramp, and the problem you're attempting to solve is to do with the IK'ing or foot visual placement, you could instead have a more detailed physics mesh that is accurate to the steps *and* a ramp. The ramp is set such that it only interacts with the player capsule, and the higher detail mesh is set such that it only tests against IKs. Solving all the other "step-like" cases (via a similar raycast clearance check like you're describing) is generally much simpler if you can eliminate stairs from that equation. This was a great video! Thanks for making it!

5:03 "you can't hide the stair problem, you just put that work somewhere else" great line. I really liked, really liked this. Presenting historical solutions, then ultimately a solution 'better' than those, and mentioning which cases were covered and not.

I don't understand how this professionally made video has only few views but I'm glad it got recommended to me.

I heard of a case between BOTW and TOTK, where in the latter game Link's ladder climbing was changed, including having him jump farther up the ladder when beginning to climb. A result was that a really short ladder on the top of Hateno Ancient Tech Lab became unclimbable because it's shorter than the distance Link jumps up it.

Great vid! Thx for adding SMO clip!!! Made me smile.

Something interesting, ive been into game development for like half a decade now (and sadly am not really close to being in the industry because that's less knowing what to do and more networking skills...) but one thing I can say is... This is exactly what ive done in 2D with gamemaker studio. But instead of stairs its slopes, but they are pixelated slopes. So effectively stairs. And the tutorials ive followed for that work in the *exact* same way. Which is ironic because as ive started working with Unity ive found they do slopes in Unity much differently.

I've seen Lost Judgement(Judgement is a spinoff series from the Yakuza/Like-a-dragon series) do some really impressive foot kinematics with actively moving escalators.

never knew there was so much to know about stairs in video games, very educational and thnx for bringing this to the public. Hope many nice things come from it.

This is awesome! I wonder how this compares to the Unreal 5 equivalent and their new ik hand and foot stuff. Give’s me a better understanding, as a 3D artist, of level design things to be aware of!

I was wondering if a non-dynamic floating capsule could help you (similar to the Toyful games method but without using forces). In essence, always having your collider a certain distance over the ground, this distance being your step height.

Great video. I might have to give your KCC a try this weekend at the GGJ. Maybe get crazy and try to implement it in a networked game.

There's a handful of games I've played in which the devs created an entirely separate animation for going up or down stairs and with how complex the whole stair problem is, I have so much respect for them. That must've been one hell of a project lmao

I tried running the demo linked in the description and found it unplayable. The mouse tracking was turned all the way up to 11, where the tiniest movement of my mouse would send the camera zooming to extreme up or down orientations or spinning wildly left or right, and any sort of subtle control was impossible. Can that get turned down a little?

Just look at literally any game from Naughty Dog. They mastered stair animations since Jak & Daxter and it only got better from there. TLOU has a completely separate animation set that activates when the player interacts with stairs, making climbing stairs slower, but more realistic because the feet land on each and every step perfectly. Naughty Dog's inverse kinematics systems overall are just mind-blowing tech in every example they come up in.

I have to say, it depends on many things if this solution works for your game or not. For example using a ramp or having a capsule collider just hit the step doesn't work on some physics configurations. The same goes for your snapping technique. It works like you said in most cases. Many games like sonic on sega game gear even made extra physics checks on the player for edge detection and so on. Which you get for free with your stair check if done correctly (correctly means in game dev if it fits your game, because there are multiple solutions to that as well). Snapping the player might have two issues for example: 1) the rough camera movement might look strange and might be better with a "ramp" 2) if the player as physics entity can move boxes around and so on. This snapping might depending on physics engine create a big force because of the moved in 1 frame. Let's say you have 15 cm stair and a 50 Physic Updates per second then you moved the player in that frame with a velocity of 7,5 m/s or 27 km/h, which is a normal human full sprint against an object. If you snap that upwards in your physics engine this might have unexpected behaviour to the game simulation. So depending on what you want a jagged foot on a "ramp" is the better option. Don't get me wrong, the video and information you provide is awesome! I've testet your Controller in the Browser Link you provided. I can make the character fly above a stair: ibb.co/FwpmwKt

this is really interesting to me specifically because of how much I play Destiny 2. that game has highly detailed environmental collision boxes that can be somewhat frustrating to deal with because of how they interact with wave generating projectiles. There are a number of weapons in that game that have projectiles that generate a damaging wave that travels along the ground based on the direction the projectile was moving as it hits the ground, and this almost guarantees that if you try and send a wave up a staircase it will hit the face of a stair, bounce off, instantly hit the surface of the next stair down, and then send the wave down the stairs toward you. there's also plenty of other heavily greebled angular environments that will do this to you if you're not careful with your shot placement (especially vex architecture.) I always figured it would have been so much simpler for them to just make ramps and hide them like you mention, but this video has given me so much insight into the problem that it is clearly more complicated than I gave them credit for.

A very common variation is to run a "body" capsule at just above the step height, and then do a sphere cast from that position down to the ground. It's effectively the same thing, but ends up a little cleaner code and you get fewer re-tries if you have some jagged terrain and potentially a low ceiling, where you have to re-try collisions after adjusting height. But otherwise, this is fairly standard. There's some additional magic a lot of character controllers will do for hip offsets to reduce IK over-extension and to also make the character movement both up and down the stairs a bit more smooth, but that's sugar on top.

I've always use ramps/slopes for my stairs, just got used to it from using Hammer editor half my life.

Hey Nick! What a great video. I don't even make video games, but as someone who finds programming interesting this video was amazing! Even though it was entertaining and instructive I would've really liked to see clips from games where stairs were NOT implemented correctly. While I am writing this I realize you might have done so without me realizing. If that is the case I would like to apologize. But for someone like me who doesn't have a lot of experience (or none at all) with making video games I would appreciate if you could have told us what is correct or (close to realistic or the most used solution) while shwoing examples of both, While watching the video I was not sure if the character was considered moving smoothly or realisticly. Anyways, this is an amazing video and you have certainly earned another subscriber.

What a great video! I'm surprised you have so few subs--well you earned one

Okay, turned this on on my TV, and pulled up my PC to comment. You're RIGHT!!!! I was not high enough for that intro. Really intrigued by the concept though, so excited to learned something new. Here's a like for the intro.

I've been looking into using the normal character controller in Unity to handle player movement, in which I will only use slopes to act as stairs, but then i'll have a stair model which will be used for the IK. That way the player moves smoothly over the simplified terrain while the animations are based on what is visually there. I get this increases computation time, but it should be negligible. TLDR: -Simplified slope geom collision for player character controller -Complex stair/terrain geom collision for player IK/animations

Great video, on a fairly interesting subject that not a lot of people think about. I just want to say while this definitely works, it also suffers from its own problem. Jittering. Since the character now snaps to the floor they and up looking unnatural, and in some cases it can hinder gameplay. Imagine a shooter game where you want to go for the headshot on an enemy as you sneak up a staircase, and just as you're about to fire you walk up a step and now your aim is entirely off. I think most games do in fact have a step height, but still use slopes because they both solve somewhat different problems. Personally the best solution I have seen for this kind of problem, that honestly seems very robust, is Horizon Zero Dawn's system. They use 4 raycasts around the character, and construct a collision plane from the results of those (plus some more tweaks in certain edge cases) and constrain the movement to it. I highly recommend wathcing their gdc talk called 'Player Traversal Mechanics in the Vast World of Horizon Zero Dawn', as it's incredibly interesting.

How do you handle the movement with the rotating platforms? Check your ground cast for a rigidbody and apply their velocity to yours?

Im struggling to understand what the issue is that hasn't already been solved. UE for example, has a max step height var on their character class to define the max height the character can step onto. This has been in since the beginning of UE4 as far as I can remember. (Well over 10 years now) How is what youve described different from this? Using the max step height, its just a case of using IK to place the feet on the actual step and move the hips down slightly. One of the main issues i can see people having is with the characters skeleton not being setup correctly (bad bone orientation) which would result in strange behavior when trying to do IK. Adding smoothing to the cameras z movement is easy enough to help combat the jerkiness. Am i missing something?

The discussion under the video is amazingly academic. It deserves to be summarized into a full paper.

IMO the best early stairs were from the Castlevania series... specially Super Castlevania IV from SNES. The way the character feet glued to the stairs always dragged my attention. It had such an animation smoothness in the cost of the freedom of movement.

would it be possible to do some interpolation on the snapping to make it feel smoother?

I have a couple problems with this video, but let me take the lead on this instead of complaining. First, a character controller can help determine what is an acceptable slope. Secondly, your stairs foot length should be relative to your animations making relative sense with the speed at which you move. Next, I use a ramp shape as a trigger. This can tell your camera to ignore the bumpiness by slerping. Lastly, you can make an event that triggers the use of a separate animation and movement speed so that it feels clean or choose some other result. I personally use Unity's free addon of generated inverse kinematics for this so that my feet will always match the steps that I walk.

Metal Gear Solid does really good stairs. It locks you into an animation.

I’ve been watching this guy make content for 23 years, he has always been awesome! I still have trouble walking up stairs irl sometimes

i cant believe this guy doesnt have more subs, he def deserves at least triple what he has now because this is good content

The only solution that i could think is making especific animations for stairs by "press a to use" and you go up/down or to have the entire animation controlable by limited controls, up/down or align with the camera angle. And this "auto-animation" will have 4 versions: walking up/down and running up/down (last two skipping some degrees). The good side is will be more realistic, but other side is that will cost so much time because you will have to make an animation for each stairs or make an entire engine for just the stairs locomotion. Thats why stairs is just another ramp.

I think anyone who's tried to write a character controller for a game knows how much of a headache stairs and slopes are

This may not work, but the jarriness of the snapping up may be fixed. What if rather than snapping directly up, the player collider is pushed at the angle of the stairs (by calculating the height which it would need to snap up to, combined with the characters forward speed), and temporarily turning off collisions between the player collider and the stair collider, until the player collider is no longer intersecting the stair collider. So in effect the player collider treats the stairs as a ramp while going up, while also allowing the separate colliders on the feet to interact with the actual shape of the stairs for inverse kinematics. Similarly while going down the ramp, the distance the player collider would have to be snapped down in your example is used to calculate the angle of the stairs, and so momentum is given in that specific direction. Any thoughts on this?

Very interesting video! I had a question because the worst stairs I see in games are the ones you walk up and the camera jitters for every single step. It's like the camera also snaps up the same height of the stair and it is extremely jarring. Is that more of a camera issue that can get smoothed out? When you first mentioned snapping I got bad vibes but now I think it's just a problem being moved to something else.

whats the game with the little green knight in the intro called again? ive played it before i just cant remember what it is

Nice video but you forgot to mention the easiest trick in the book: using an invisible plane with a special collision flag for feet collision. It's extremely cheap in terms of computations and provides the smoothest surface possible, you won't have any head bobbing in First Person view no matter the steepness so it works very well for FPS. Only drawback is that you have to set them up manually (but in most cases you have to create invisible walls in the level anyway) and they're not the best for spiral stairs with short radius (but these are rare in video games). This technique is used in World of Warcraft for both straight and spiral stairs. Also I don't think OW use a custom collider for climbing stairs, the body collider is actually much higher than the character's feet (somewhere around the knees). Instead the ground probing is achieved with a raycast and the feet position is smoothed to prevent jitter. For stairs and nearby floors, I believe the topology around the character's feet is analyzed to find the best possible floor height. This allows the character to stand on nearby platforms, even if the character's feet don't touch the platform.

I am pretty sure that back then when I tried to make a little game prototype... I just added ramp on spring linked to the character instead of building ramp into the map. No ray cast only rigid body physic and box. Then I also attached the leg with spring to the skeleton with the animation then linked the feet to a rigid body collider box. It can be really glitch though. I am still doing it that way in Blender. Though in blender I made the feet and leg out of an inflated balloon of heavy cloth simulation to simulate muscle too. But it is the same concept, even if skeleton clip trough the ground the the feet wont be able to follow the skeleton. Then with a flexible cloth sim the feed bending is pretty convincing. Also we can build internal triangular structural trust beam with really high internal pressure to simulate actual rigid material. Then link the skin to the beam. Then delete the rigid part with a mesh node just after the simulation so it wont affect the the final subdivided look. Though doing rigid part use a lot of simulation step. It is often better to just add a couple of pinned vertices near the skeleton for faster simulation. Usally a body done like that sill run in real time or near real time if the base mesh is wheel done and optimized. If not then it is possible to use a lower poly cage for the simulation... The joke is... it is actually easier and faster to setup in blender than a rigid body rag doll. Rigid body linked to bone are really annoying to do in blender. What I did too was adding speed buoyancy to be able to simulate car, atv and snowmobile crossing lake at high speed. Took me a while to get it to work as good as expected but since then I wonder why so few game seem to include that physic. It is a pretty common phenomenon and it is really fun to do... Going over a lake with something that ca not really float is pretty entertaining. Though most game studio are in the middle of city... And driving over a lake with snowmobile at 100mph is probably not something developer know that much. I guess probably...

I appreciate this video. There aren't enough think pieces about character controllers IMO

What tool or asset is used in the video to create stairs?

4:42 "If your character can't handle walking over some broken steps or jagged terrain, just get rid of them" Sounds good to me! *Deletes game character

Also i have found a way of adding points of walls to list and checking distance between player feet and highest part of stairs, and interpolating between stairs

I use a collision shape that sticks out in front of the player and the movement direction vector rotates it around the players central axis. This makes it so you can't backup stairs, just a design choice. It has a collision mask that looks at the layer I assign to stairs and curbs etc. Then it lerps the character to the collision point when colliding and receiving moving input. The lerp speed is in relation to the players walk or run speed. It works pretty well. And I don't need to pass any variables for max height step etc cause it's a physical region that's contained within the shape... but it's a very similar approach

Thank you for explaining all of this. I notice stair movement all of the time in games but I don't know much about development so I can only guess what's happening. It's nice to know what's happening when I notice these things.

What method do you think Rockstar uses in Grand Theft Auto V? Walking up and down stairs in that game feels quite realistic from my experience

I think for most games, a fairly practical solution is to separate the collision mesh from the visual appearance of the stairs. You can then base the position in which the character is shown on the terrain mesh. This allows the camera to move smoothly up and down, while also making your character look like they're firmly grounded. It also signals intent. If you just leave it up to the physical characteristics of the terrain, you might get situations where a player can walk up something they're not supposed to, like for instance up the seats of bleachers. What you want to allow the player to do in situations like this is going to depend on the kind of game you're making. Not everything needs its own collision mesh though. Most terrain will be fine with either using the terrain mesh for collision (like slopes, floors, paths, etc), or not having collision at all and just use IK to smooth things out (thresholds, cobblestones, branches, etc). Of course I agree that it would be ideal to use a one-size-fits-all solution, but in practice that often ends up being more restrictive than liberating. I think a separation of the different concerns of rendering, movement and IK is a far more elegant solution. And you can define all three for each of your terrain elements depending on their intended function, which will allow the level designer to place them down without worrying much about it Your stairs then come with a sloped collision mesh pre-installed, so no matter how steep or shallow they are, they function like stairs. If you don't want your stairs to function like stairs, you can add an exception for a particular instance of that element... or better, place down a different element that wasn't intended to be walked on top of. The only real snag with this system imo is if you want the same element to function differently in different situations, for examples because either the player or the terrain can shrink/grow. In that case, it might be better to use the system you present in this video, since the intent is to let the player traverse big objects not meant for walking on when they're large, and stop them from walking up even small steps when tiny. So if the intended way for a player to interact with something changes over the course of the game, you want a way to deal with that. It's always tempting to design things like we see them in the real world. In the real world, if we can touch an object, we can stand on it and collide with it. But this isn't a design feature. Rather, it's a restriction. We build stairs precisely because we can't walk up walls when the need arises. We want our game to mimic the way things look in real life for the sake of familiarity, but that doesn't mean it has to work the same way under the hood, unless you want the amount of extreme realism from your game that really only VR games could benefit from at the moment. In conclusion, this is what my critique on your movement system boils down to: it doesn't have a concept of intent, and takes any non-visual design work out of the normal level and world design processes. I think that in most cases, "intent" is a crucial thing to have at your disposal when designing. You want the player character to interact with the world as the world wishes, not as the player character wishes, or you'll run into lots of problems later where the intent of your design doesn't match what the player can actually _do_ there. These different elements should not be made to rely on one another if there's no need for it. It just makes things more complicated. There's something nice and declarative with having collision, appearance, and other such properties separately defined on level elements, and it makes it easy to fix problems without having to introduce a whole host of new ones. It's a flexible system, whereas this one is inflexible. Ask yourself what you will do if your level designer comes to you and says, "I want the player to walk up these stairs, but they can't. I also want the player to be unable to climb this slope, but they can." Are you just going to tell them "that's not how physics works, so deal with it"? I don't think this video or your work on OpenKCC is useless. Far from it. It's very impressive. But I think it's also important to realise and accept what its limitations are, and what it is _not_ suited to.

A thought I had that could work with more testing: Two ray casts on the hips (one ray left hip, one ray right hip) pointing down & the slightly in the direction of player move input, place (IK) each foot model where ray hits collider. Limit ray hit detection height depending on preferences & move body up until knees are unbent (Lunge).

Thanks a lot this really helped me fix my character controller when I could not figure out what was going wrong or why with steps and slopes. Tired out the controller already had the feature but I did not know what they were called. Thanks a lot I hope to make videos of this quality myself someday.

This is very similar to the solution in Super Mario 64, though SM64 does simple vertex collisions rather than using a robust physics solution like Unity's.

yes, stairs are great and all... but the foot sliding is killing me!

I'm not even a game dev (Wish I could) yet, but still I love watching this type of content, good job mate :)

How well will this work on a rotating cylinder habitat with different portions rotating at different speeds or not at all? I feel like this assumes the ability to snap down is available which isn't necessarily going to be true.

surprised the metal gear solid series wasn't brought up. Always liked the approach they took

I still think the "hiding" part (pushing it to the level designers) is the best one still. Snapping up stairs isn't perfect like you mentioned but far worse is that in first person you dont want the camera snapping upwards, it's incredibly immersion breaking and jarring. You can smooth out the camera but that has its own issues with feeling floaty and detached and slopes can mess it up etc but if the game requires precise aiming then that smoothing is even worse of a tradeoff. The best solution is pushing it to the level designers+snapping, which is what CSGO uses and they've basically perfected smoothing out stairs with ramp colliders, it checks all the boxes it's smooth, you don't notice it so no immersion is lost, it keeps the camera steady and not floaty (mostly, there is still some from older source games that just had snap and camera smoothing like CS:S), and you never snag on anything random. I think it's the best of all worlds.

Not sure why this got recommended to me, but it's a fascinating topic. I remember the first time I read about special attention to stairs was in a preview article about Soul Reaver 2, where the developers made special effort to make Raziel's feet connect with stairs. They solved the problem with running up stairs by making them extremely long and shallow stairs, so one footfall landed on each step. Like you said, this is shifting the problem to the level designers.

If you look at stairs in games historically, you notice that in older games with limited polygons they often would solve two problems in one stroke: make all stairs ramps with a texture, to give them the illusion of having steps. Come the turn of the millennium as world detail got more... detailed, and a lot of game dev was applying old techniques to new projects. So game devs would by default build ramps, and then the art team would make them LOOK LIKE stairs, sometimes by having a mismatch in visible modeling and what the character model was actually interacting with. This of course would create some problems, in that someone walking up a ramp doesn't look the same as someone walking up stairs, and we want things to look good and correct. Which is where the divergence that created The Stair Problem happened, and by extension two major camps of philosophy for it: Camp one, which is trying to make the Disguised Ramp solution still work, often with tricks like having the secondary stair models have collision, but only with the leg actors for the purpose of making realistic step animation, meanwhile the actual player entity is a scarecrow shaped thing that just floats up the invisible ramp while the fake legs do their thing. This also necessitates a smoothing of the general world's collision to prevent the Very Short Wall Problem mentioned in the video. Camp 2 just makes the stairs real for the purpose of all physics, and then solves the problem from that point, which is where this video lies. A veteran dev that's used to Camp 1 might say it's a waste of effort to take this route but it depends on what needs to happen in game; if the only interaction that occurs on stairs is unimpeded walking, then the ramps posing as stairs solution might serve well enough. But if there's more going on in those moments, like combat, realistic wheel interaction, etc. Then Camp 2 has a lot more reason to work out the quirks of how something should realistically interact with small vertical steps.

Yep , the his work is much better. My first idea was to make objects of stairs then player check if its a stair, then play certain walking up and down animation and stuff. i think mine would cause bugs so i wouldnt do it, the video makes more sense.

The way the snapping works looks completely unnatural to me. You can tell just by watching it that it's snapped to the surface, it doesn't feel like you're walking up or down a surface it looks like you're walking along it, glued to it. If I walk fast off the edge of a step I don't immediately snap down, I get a little air time, with appropriate speed and gravity configured "falling" down a stair is more realistic. In real life if you're walking briskly down a stair, you don't fully stop moving downwards when you put your foot on the step below, your leg continues to bend allowing your center of mass to continue moving downwards slightly, but other than that you really are doing a controlled fall with every step. Something similar happens with stepping up, you are pushing yourself up with your feet, but if you're doing it at speed you also maintain some upwards momentum from the previous steps, effectively tiny jumps. The physics behind stepping up and stepping down is an entirely physical mechanics problem which is difficult to simulate with only primitive colliders. The most accurate form of dealing with steps would be to simulate the forces on an actual skeletal system with the feet targeting and being planted on the ground via a predictionary system that looks for viable spots based on current momentum, expected trajectory and current limb placement (Think of this like the current IK system used for animating moving up steps, but the positions actually used for the calculations themselves not just visual). This would be computationally expensive, but not prohibitively so, the main problem would be the complexity, combining such a system with the more traditional collider-based controllers would be rather tricky, so you'd likely have to design the entire character controller in this style which would be far more complex and would have it's own difficult issues to solve.

Why is this literally the most helpful video I have ever seen?

You should've mentioned the staircase saga directed by 3kliksphillip on subject of cs go stair clipping. That's the whole point of "we just drop the problem to our level designer". CSGO mappers just suffer from this problem the whole 11 years. You have to add ramp to stairs up'n'down. Now you have to smoothen out stepping on stair from aside. Now you have to clip out the cornered staircases. And now you'll meet a boss: spiral staircase (much like on dust 2)