Clicked on this to watch a GDC talk about video game mechanics, ended up essentially watching a refresher lecture that I remember taking during first year Physics

Worth noting that Mario switches to heavy gravity on jump release even if peak hasn't been reached yet, giving you jump height control. That was the original reason for it to be coded that way. But in general, yeah, having acceleration change on up and down movement and with jump key held/released tends to give the nice responsive jumps you see in the platformers we tend to remember. And the specifics of what gravity should be on each segment and whether pressing the jump key again after releasing it makes a difference is up to specific game implementation.

25:13 Kind of uncool forcing him out the podium.

4:25, 9:48, 12:58, 16:25, 19:58, 22:37, 25:18

Short note on the integration methods: Euler integration doesn't conserve energy, so what happens is that when we try to approximate a continuous jump curve, in each discrete time step we will travel in a straight line in the same direction as (tangent to) the curve. Over many time steps, the error from choosing a straight line will accumulate and deviate from the "real" curve. Depending on how you do your update function and how it depends on each frame, a frame rate drop might make this error more noticeable. Runge-Kutta 4 is very accurate but also doesn't conserve energy, but the error grows very slow and won't be noticeable during a single jump. However, it is a bit expensive to calculate. And then comes Verlet, which is cheaper than RK4 and conserves energy. The accuracy depends on the timestep though, so it probably won't be as accurate as RK4, but it generally works better in games.

if you are using unity, Sebastian lague have a great tutorial & source code available that does this just search for " [Unity] Creating a 2D Platformer (E03. jump physics) "

I guess sometimes we keep up with the advanced stuff and forget about the basics... I really needed all that Physics Introduction review. Thank you, Kyle!!

Is there an extreme stereo effect on this video or is it just me? If he moves two inches to the right, his voice gets almost completely panned to the right channel, idem for left channel. I wonder if this was recorded with two mics on stereo channels (WHY?!) or the person who did the edit of this video was just bored to hell and decided to pan the speaker's voice each time he moved just a little tiny bit.

Really liked the talk, many thanks! Also, downloaded the game, liked it too :) Jumping felt great - clearly know what you're talking about :)

Parabolics completely smoothed out my moving platform code. I was looking for good parabolic integration over the Euler method I was using and found it! Thank you.

I wish I had known GDC had their own youtube channel sooner. This is great. Getting passed the crappy audio, I sat through this entire lecture and both facepalmed at how close I actually got to something similar to this on my own, and learned a great deal at the same time.

Nice to see Leonard Hofstadter doing science talks again.

Bro, that guy was so rude to the guy speaking. Watch till the end to see who deserves the 2016 douche award.

This is a superb, superb tutorial. Thanks Kyle!

Excellent treatment of this material. You Have To Win The Game looks fun and nostalgic also.

Just happened on this video. As someone who tried to fix the, "floatyness" of UE4's standard jump back in school it was a really interesting talk.

Incredible talk! Also, I love Minor Key Games' projects. Insanely satisfying platformer physics, great work.

YOOOO, I've won the game a long time ago, and I'm a fan of the mechanics. I'll have to look back on that game in reference to this video later.

Here's my resulting code after watching this and the tutorial series "[Unity] Creating a 2D Platformer" mentioned below. Hopefully this will be useful for someone. // Calculate the gravity and initial jump velocity values _jumpGravity = -(2 * JumpHeight) / Mathf.Pow(TimeToJumpHeight , 2); _jumpVelocity = Mathf.Abs(_jumpGravity) * TimeToJumpHeight ; // Step update stepMovement = (_velocity + Vector3.up * _gravity * Time.deltaTime * 0.5f) * Time.deltaTime; transform.Translate(stepMovement); _velocity.y += _gravity * Time.deltaTime; // When jump button pressed, _velocity.y = _jumpVelocity; NB. that is for a simple jump, no double jumping, differing gravity when descending, etc. Those things should be trivial to solve; the meat of the 'better jump' is calculating velocity/gravity from a desired height variable and time to reach it variable, and implementing the "velocity verlet" when calculating the step movement (+ gravity * deltaTime * 0.5). I wish I understood the math behind this stuff a bit better, but just knowing how to implement it is good enough for my purposes.

Very interesting video, I updated my falling system with this. Thank you! One question: I didn't get very well how should I update G using the Runge Kutta integrator, given the position offset previously defined. Thanks

That was really nicely presented and explained.

This was pure gold, thank you so much for sharing!

Nice talk! I wish I could see your talk right before the starting develop the game.

I learned about the Verlet algorithm while doing Molecular Dynamics. I'm surprised to see it applied to videogames. :-)

Thanks for laying this out, I've been messing with different ways of doing jumps in my platformers. I'll have to try this one out

How about only programming the height of the jump an speed of the character going up the porabula could be just controlled by moving forward at the same speed as the characters standard running or walking speed based on which direction the character runs Example:If I run to the right and push space to jump the character should move right at the same speed just traveling up in the air also coming back down

Are the integration techniques used to manually implement parabolic jump in a game engine without physics? or are there other use cases that I have no idea of? Thanks!

Yeah, I used rk4 to simulate projectile motion in curved spacetime.

Does anybody knows where does the example sprites come from? I really liked them

So he’s saying use your known values such as height and distance to find initial values like starting velocity and gravity. Do that for each scenario/parabola and apply those velocities and gravities given the conditions are met.

i remember all jump possibilities in super mario 3d world, and it is amazing. wamdering how it was programed

So... I want to make a General Relativity raytracer. I got the maths I want to use, but where do I start with the programming? I can calculate the light paths by hand, on the computer, but I want to make images with this data I can calculate. I know c++, cuda, sfml, and some other stuff, but I need to use some pretty efficient stuff.

Tl;DW: Use variable gravity to design your jump mechanics.

time 9:25 or so for "how to choose initial velocity and gravitational constant in order to get any given jump height and time to reach the top of the parabola".

Wow learned more about physics from this than high school...

THANKS IT HELPED A LOT WITH MY PLATFORMER

I suck at math and still program, this is why my games suck! I get it now lol. I really need to consider getting better though, or I will keep making crap. Thanks for this video it really helped : ) No room for lazy!

very helpful, thank you!

I am loving thus channel

boy I wish I had more than middle school level math knowledge

I don't understand one thing, if someone can make it clear. How can you use V0 in equation on Th considering V0 on Th is 0 and it is gTh + 0 = 0 and not gTh + V0 = 0?

Akward ending for him lol

I only have one question. What?

More interesting than i thought! Only the way of the of the speaker to end each sentence by pressing out the last word without breath is very distracting, once i noticed it.

This is pure gold !

1:13 lool that fat cat jump thoe, never gets old - Geronimooooo!!! ;'D

there should be mono sound checkbox next to quality settings @youtube

This is very -chug down liquid- Insightful. Thank you~

The picture in 6:00 is missleading of course the height also changes with g

One this I can't recommend enough: automatically crouch jump every time you jump. If you want to be able to jump up a meter tall object, what do you do, do you throw your 1.7 meter forehead 20 centimeters deep in your 2.5 meter cieling while moving your center of mass a whole meter vertically? Or do you lift your feet and tuck your head so that a jump that only launches your center of mass 40 centimeters in the air lets you clear a meter high object? I know which option I choose.

This guy could play the archetype nerd in any sci-fi film. Wild accent.

This is great stuff. Just a nerdy nitpick - you're not "momentarily weightless" only at the peak of the jump, but are in fact weightless throughout the entire parabola.

every time he says "back" i think of kyles cousin from NY in South Park. Trolly accent. Grevity.

This is awesome!

This dude is awesome.

I had an issue I solved where the final height of a jump never quite reached the specified final height. It turns out that it was off by height/t^2. I'm not sure why, but I fixed it by adding that to my initial velocity. Just putting this here in case anyone has the same problem, spent hours in Desmos calculator trying to fix it...

...I just played the game showed in the thumbnail of the vid and the game's physics is great not gonna lie

to this date, this is the best gdc talk ever... thak you so much Kyle Pittman

Just making sure I follow, this all assumes a kinematic character movement right? As in, we're simulating the gravity, right? I'm wondering because I'm lost on why the latter part of the video deals with updating our acceleration when I'm here just using Unity's built-in gravity. Not sure how to implement any of this. (To be clear, this is in no way a critique of this video. I am, in fact, humbled by just how little I know, and realize this might be a noobish question.)

How do I apply this in Unreal?

grayvity and paraybolas

3:55 My favorite autocomplete typo: textbox physics. :D

So how do you keep the distance you can jump constant with variable gravity?

Loved this! Great presentation, well presented and very informative.

Es un genio este péndulo

This guy gives off huge tim sweeny vibes, he even sounds like him hah. Very good talk and interesting!

Holy shit that guy at the end was an ass. Great talk broski.

Hey cool idea man. I totally agree with using parameters that are more useful to designers than physicists. I do have one question though, typically we use a physics engine and add forces and such to make things move around, with the benefit of them responding to the environment and other physical objects. With this method, everything is isolated in it's own world. Did you have to build your own geometry collision and how did this interact with your jump equations?

I found this really interesting, but I fully admit, a lot of it went over my head. I decided to try following along in GameMaker. The first section about defining a jump in terms of jump height and time-to-peak went absolutely fine. When the next section comes along talking about defining jumps in terms of height and distance (my goal) it goes horribly wrong. I followed the substitute calculations at @13:10 and the gravity value is giving me a wildly different number resulting in tiny tiny hops compared to the height/time version. Can anyone confirm they have followed this (not necessarily in GameMaker) and had it work? I assume I am doing something wrong or GameMaker has a bug, since this guy seems really smart and I'm sure he would have noticed a massive mistake while presenting even if it had slipped into the PowerPoint.

They way I'd do it is store the frame(s) when the player pressed/released the jump button when applicable for the jump and the current frame value. Use this with a numerically stable variant of the exact formula instead of integrating.

Who's here after Pontypants video? xD

runnin on that schedule

This guy's accent is wild, he's dropping t's like I would expect from the english but he sounds american?

I don't get why would you do incremental approximation if you can just calculate the position (and the velocity) from the last singularity (launch, change of gravity, etc.).

Celeste, the best platformer game I've ever played so far.

Can we get the _Thomas was Alone_ guy to give a talk about jump mechanics?

My opinion: Don't derive position, but rather velocity or force. Whichever one is easier to work with on your game engine. If you derive position, you won't be able to react to physics objects very well.

How about some maths to fix the audio? :/

Wow not one mention of rb.velocity ..

What game is in the thumbnail?

The audio makes me nauseous.

gold

The talk that takes place after this one is called "Math for Game Programmers: Juicing Your Cameras With Math"

Hello, what I'm need to do, if I jump from very high place, how calculate how much I go forward?

Is this going to be on the test?

GitHub example？

It's sad they didn't talked about Coyote Jumps and Hangtimes, but it was pretty good nonetheless

I wonder if he might be from the northern NY - Rochester - or maybe Minnesota region…

Interesting, but after doing 15 platformers, it's much faster to begin with setting the gravity and other stuff upfront and just tweaking...You develop a feel for what the numbers map to in terms of movement.

did he just close his laptop?... really dude?

Someone please tell me that this is not the typical level of math competence of a game developer...

Or you could just do it like they did in the old days and get a *deterministic* and *precise-feeling* jump. if (jumpkey pressed && grounded) yvelocity = jumpvelocity; y += yvelocity; yvelocity -= gravity;

I don't get it, why the thumbnail is WIn the Game which doesn't follow ANY of the rules set in this presentation? LOL. Also it's a good reference for what can be different from this system

Good discussion. BTW - Say: "Button" or "Buhun"?

Close your eyes... It's Jared.

I am terrible at math, too bad pretty much 100% of this went over my head.

tfw windows removed the option to set your headphones to mono

Got lost when the slide showed Integration.

i didnt know david wallace joined the videogame industry

I teach game development at a university. When my students ask me when we are doing jumping, they are always so confused about why I tell them that will probably have to be in the advanced coding class lol.